[[bbv2.reference]] = Reference [[bbv2.reference.general]] == General information [[bbv2.reference.init]] === Initialization Immediately upon starting, the Boost.Build engine (*`b2`*) loads the Jam code that implements the build system. To do this, it searches for a file called `boost-build.jam`, first in the invocation directory, then in its parent and so forth up to the filesystem root, and finally in the directories specified by the environment variable BOOST_BUILD_PATH. When found, the file is interpreted, and should specify the build system location by calling the boost-build rule: [source] ---- rule boost-build ( location ? ) ---- If location is a relative path, it is treated as relative to the directory of `boost-build.jam`. The directory specified by that location and the directories in BOOST_BUILD_PATH are then searched for a file called `bootstrap.jam`, which is expected to bootstrap the build system. This arrangement allows the build system to work without any command-line or environment variable settings. For example, if the build system files were located in a directory "build-system/" at your project root, you might place a `boost-build.jam` at the project root containing: [source] ---- boost-build build-system ; ---- In this case, running *`b2`* anywhere in the project tree will automatically find the build system. The default `bootstrap.jam`, after loading some standard definitions, loads both `site-config.jam` and `user-config.jam`. [[bbv2.reference.rules]] == Builtin rules This section contains the list of all rules that can be used in Jamfile — both rules that define new targets and auxiliary rules. [[bbv2.reference.rules.exe]]`exe`:: Creates an executable file. See link:#bbv2.tasks.programs[the section called “Programs”]. [[bbv2.reference.rules.lib]]`lib`:: Creates an library file. See link:#bbv2.tasks.libraries[the section called “Libraries”]. [[bbv2.reference.rules.install]]`install`:: Installs built targets and other files. See link:#bbv2.tasks.installing[the section called “Installing”]. [[bbv2.reference.rules.alias]]`alias`:: Creates an alias for other targets. See link:#bbv2.tasks.alias[the section called “Alias”]. [[bbv2.reference.rules.unit-test]]`unit-test`:: Creates an executable that will be automatically run. See link:#bbv2.builtins.testing[the section called “Testing”]. [[bbv2.reference.rules.test]]`compile`; `compile-fail`; `link`; `link-fail`; `run`; `run-fail`:: Specialized rules for testing. See link:#bbv2.builtins.testing[the section called “Testing”]. [[bbv2.reference.rules.check-target-builds]]`check-target-builds`:: The `check-target-builds` allows you to conditionally use different properties depending on whether some metatarget builds, or not. This is similar to functionality of configure script in `autotools` projects. The function signature is: + ---- rule check-target-builds ( target message ? : true-properties * : false-properties * ) ---- + This function can only be used when passing requirements or usage requirements to a metatarget rule. For example, to make an application link to a library if it's available, one has use the following: + ---- exe app : app.cpp : [ check-target-builds has_foo "System has foo" : foo : FOO_MISSING=1 ] ; ---- + For another example, the alias rule can be used to consolidate configuration choices and make them available to other metatargets, like so: + ---- alias foobar : : : : [ check-target-builds has_foo "System has foo" : foo : bar ] ; ---- [[bbv2.reference.rules.obj]]`obj`:: Creates an object file. Useful when a single source file must be compiled with special properties. [[bbv2.reference.rules.preprocessed]]`preprocessed`:: Creates an preprocessed source file. The arguments follow the link:#bbv2.main-target-rule-syntax[common syntax]. [[bbv2.reference.rules.glob]]`glob`:: The `glob` rule takes a list shell pattern and returns the list of files in the project's source directory that match the pattern. For example: + ---- lib tools : [ glob *.cpp ] ; ---- + It is possible to also pass a second argument—the list of exclude patterns. The result will then include the list of files matching any of include patterns, and not matching any of the exclude patterns. For example: + ---- lib tools : [ glob *.cpp : file_to_exclude.cpp bad*.cpp ] ; ---- [[bbv2.reference.glob-tree]]`glob-tree`:: The `glob-tree` is similar to the `glob` except that it operates recursively from the directory of the containing Jamfile. For example: + ---- ECHO [ glob-tree *.cpp : .svn ] ; ---- + will print the names of all {CPP} files in your project. The `.svn` exclude pattern prevents the `glob-tree` rule from entering administrative directories of the Subversion version control system. [[bbv2.reference.rules.project]]`project`:: Declares project id and attributes, including project requirements. See link:#bbv2.overview.projects[the section called “Projects”]. [[bbv2.reference.rules.use-project]]`use-project`:: Assigns a symbolic project ID to a project at a given path. This rule must be better documented! [[bbv2.reference.rules.explicit]]`explicit`:: The `explicit` rule takes a single parameter--a list of target names. The named targets will be marked explicit, and will be built only if they are explicitly requested on the command line, or if their dependents are built. Compare this to ordinary targets, that are built implicitly when their containing project is built. [[bbv2.reference.rules.always]]`always`:: The `always` function takes a single parameter—a list of metatarget names. The top-level targets produced by the named metatargets will be always considered out of date. Consider this example: + ---- exe hello : hello.cpp ; exe bye : bye.cpp ; always hello ; ---- + If a build of `hello` is requested, then the binary will always be relinked. The object files will not be recompiled, though. Note that if a build of `hello` is not requested, for example you specify just `bye` on the command line, `hello` will not be relinked. [[bbv2.reference.rules.constant]]`constant`:: Sets project-wide constant. Takes two parameters: variable name and a value and makes the specified variable name accessible in this Jamfile and any child Jamfiles. For example: + ---- constant VERSION : 1.34.0 ; ---- [[bbv2.reference.rules.path-constant]]`path-constant`:: Same as `constant` except that the value is treated as path relative to Jamfile location. For example, if `b2` is invoked in the current directory, and Jamfile in `helper` subdirectory has: + ---- path-constant DATA : data/a.txt ; ---- + then the variable `DATA` will be set to `helper/data/a.txt`, and if *`b2`* is invoked from the `helper` directory, then the variable `DATA` will be set to `data/a.txt`. [[bbv2.reference.rules.build-project]]`build-project`:: Cause some other project to be built. This rule takes a single parameter—a directory name relative to the containing Jamfile. When the containing Jamfile is built, the project located at that directory will be built as well. At the moment, the parameter to this rule should be a directory name. Project ID or general target references are not allowed. [[bbv2.reference.rules.test-suite]]`test-suite`:: This rule is deprecated and equivalent to `alias`. [[bbv2.overview.builtins.features]] == Builtin features This section documents the features that are built-in into Boost.Build. For features with a fixed set of values, that set is provided, with the default value listed first. [[bbv2.builtin.features.variant]]`variant`:: *Allowed values:* `debug`, `release`, `profile`. + A feature combining several low-level features, making it easy to request common build configurations. + The value `debug` expands to + ---- off on off on ---- + The value `release` expands to + ---- speed off full off ---- + The value `profile` expands to the same as `release`, plus: + ---- on on ---- + Users can define their own build variants using the `variant` rule from the `common` module. + NOTE: Runtime debugging is on in debug builds to suit the expectations of people used to various IDEs. [[bbv2.builtin.features.link]]`link`:: *Allowed values:* `shared`, `static` + A feature controlling how libraries are built. [[bbv2.builtin.features.runtime-link]]`runtime-link`:: *Allowed values:* `shared`, `static` + Controls if a static or shared C/{CPP} runtime should be used. There are some restrictions how this feature can be used, for example on some compilers an application using static runtime should not use shared libraries at all, and on some compilers, mixing static and shared runtime requires extreme care. Check your compiler documentation for more details. [[bbv2.builtin.features.threading]]`threading`:: *Allowed values:* `single`, `multi` + Controls if the project should be built in multi-threaded mode. This feature does not necessary change code generation in the compiler, but it causes the compiler to link to additional or different runtime libraries, and define additional preprocessor symbols (for example, `_MT` on Windows and `_REENTRANT` on Linux). How those symbols affect the compiled code depends on the code itself. [[bbv2.builtin.features.source]]`source`:: The `X` feature has the same effect on building a target as putting X in the list of sources. It is useful when you want to add the same source to all targets in the project (you can put in requirements) or to conditionally include a source (using conditional requirements, see link:#bbv2.tutorial.conditions[the section called “Conditions and alternatives”]). See also the `` feature. [[bbv2.builtin.features.library]]`library`:: This feature is almost equivalent to the `` feature, except that it takes effect only for linking. When you want to link all targets in a Jamfile to certain library, the `` feature is preferred over `X`--the latter will add the library to all targets, even those that have nothing to do with libraries. [[bbv2.builtin.features.dependency]]`dependency`:: Introduces a dependency on the target named by the value of this feature (so it will be brought up-to-date whenever the target being declared is). The dependency is not used in any other way. [[bbv2.builtin.features.implicit-dependency]]`implicit-dependency`:: Indicates that the target named by the value of this feature may produce files that are included by the sources of the target being declared. See link:#bbv2.reference.generated_headers[the section called “Generated headers”] for more information. [[bbv2.builtin.features.use]]`use`:: Introduces a dependency on the target named by the value of this feature (so it will be brought up-to-date whenever the target being declared is), and adds its usage requirements to the build properties of the target being declared. The dependency is not used in any other way. The primary use case is when you want the usage requirements (such as `#include` paths) of some library to be applied, but do not want to link to it. [[bbv2.builtin.features.dll-path]]`dll-path`:: Specify an additional directory where the system should look for shared libraries when the executable or shared library is run. This feature only affects Unix compilers. Please see link:#bbv2.faq.dll-path[the FAQ: “Why are the dll-path and hardcode-dll-paths properties useful? ”] in link:#bbv2.faq[Frequently Asked Questions] for details. [[bbv2.builtin.features.hardcode-dll-paths]]`hardcode-dll-paths`:: *Allowed values:* `true`, `false`. + Controls automatic generation of dll-path properties. + This property is specific to Unix systems. If an executable is built with `true`, the generated binary will contain the list of all the paths to the used shared libraries. As the result, the executable can be run without changing system paths to shared libraries or installing the libraries to system paths. This is very convenient during development. Please see the link:#bbv2.faq.dll-path[FAQ entry] for details. Note that on Mac OSX, the paths are unconditionally hardcoded by the linker, and it is not possible to disable that behavior [[bbv2.builtin.features.flags]]`cflags`; `cxxflags`; `linkflags`:: The value of those features is passed without modification to the corresponding tools. For `cflags` that is both the C and {CPP} compilers, for `cxxflags` that is the {CPP} compiler, and for `linkflags` that is the linker. The features are handy when you are trying to do something special that cannot be achieved by a higher-level feature in Boost.Build. [[bbv2.builtin.features.include]]`include`:: Specifies an additional include path that is to be passed to C and {CPP} compilers. [[bbv2.builtin.features.define]]`define`:: Specifies an preprocessor symbol that should be defined on the command line. You may either specify just the symbol, which will be defined without any value, or both the symbol and the value, separated by equal sign. [[bbv2.builtin.features.warnings]]`warnings`:: The `` feature controls the warning level of compilers. It has the following values: + * `off` - disables all warnings. * `on` - enables default warning level for the tool. * `all` - enables all warnings. + Default value is `all`. [[bbv2.builtin.features.warnings-as-errors]]`warnings-as-errors`:: The `` makes it possible to treat warnings as errors and abort compilation on a warning. The value `on` enables this behavior. The default value is `off`. [[bbv2.builtin.features.build]]`build`:: *Allowed values:* `no` + The `build` feature is used to conditionally disable build of a target. If `no` is in properties when building a target, build of that target is skipped. Combined with conditional requirements this allows you to skip building some target in configurations where the build is known to fail. [[bbv2.builtin.features.tag]]`tag`:: The `tag` feature is used to customize the name of the generated files. The value should have the form: + ---- @rulename ---- + where _rulename_ should be a name of a rule with the following signature: + ---- rule tag ( name : type ? : property-set ) ---- + The rule will be called for each target with the default name computed by Boost.Build, the type of the target, and property set. The rule can either return a string that must be used as the name of the target, or an empty string, in which case the default name will be used. + Most typical use of the `tag` feature is to encode build properties, or library version in library target names. You should take care to return non-empty string from the tag rule only for types you care about -- otherwise, you might end up modifying names of object files, generated header file and other targets for which changing names does not make sense. [[bbv2.builtin.features.debug-symbols]]`debug-symbols`:: *Allowed values:* `on`, `off`. + The `debug-symbols` feature specifies if produced object files, executables, and libraries should include debug information. Typically, the value of this feature is implicitly set by the `variant` feature, but it can be explicitly specified by the user. The most common usage is to build release variant with debugging information. [[bbv2.builtin.features.runtime-debugging]]`runtime-debugging`:: *Allowed values:* `on`, `off`. + The `runtime-debugging` feature specifies whether produced object files, executables, and libraries should include behavior useful only for debugging, such as asserts. Typically, the value of this feature is implicitly set by the `variant` feature, but it can be explicitly specified by the user. The most common usage is to build release variant with debugging output. [[bbv2.builtin.features.target-os]]`target-os`:: The operating system for which the code is to be generated. The compiler you used should be the compiler for that operating system. This option causes Boost.Build to use naming conventions suitable for that operating system, and adjust build process accordingly. For example, with gcc, it controls if import libraries are produced for shared libraries or not. + The complete list of possible values for this feature is: `aix`, `appletv`, `bsd`, `cygwin`, `darwin`, `freebsd`, `hpux`, `iphone`, `linux`, `netbsd`, `openbsd`, `osf`, `qnx`, `qnxnto`, `sgi`, `solaris`, `unix`, `unixware`, `windows`. + See link:#bbv2.tasks.crosscompile[the section called “Cross-compilation”] for details of cross-compilation. [[bbv2.builtin.features.architecture]]`architecture`:: *Allowed values:* `x86`, `ia64`, `sparc`, `power`, `mips1`, `mips2`, `mips3`, `mips4`, `mips32`, `mips32r2`, `mips64`, `parisc`, `arm`, `combined`, `combined-x86-power`. + The `architecture` features specifies the general processor family to generate code for. [[bbv2.builtin.features.instruction-set]]`instruction-set`:: *Allowed values:* depends on the used toolset. + The `instruction-set` specifies for which specific instruction set the code should be generated. The code in general might not run on processors with older/different instruction sets. + While Boost.Build allows a large set of possible values for this features, whether a given value works depends on which compiler you use. Please see link:#bbv2.reference.tools.compilers[the section called “C++ Compilers”] for details. [[bbv2.builtin.features.address-model]]`address-model`:: *Allowed values:* `32`, `64`. + The `address-model` specifies if 32-bit or 64-bit code should be generated by the compiler. Whether this feature works depends on the used compiler, its version, how the compiler is configured, and the values of the `architecture` `instruction-set` features. Please see link:#bbv2.reference.tools.compilers[the section called “C++ Compilers”] for details. [[bbv2.builtin.features.cpp-template-depth]]`c++-template-depth`:: *Allowed values:* Any positive integer. + This feature allows configuring a {CPP} compiler with the maximal template instantiation depth parameter. Specific toolsets may or may not provide support for this feature depending on whether their compilers provide a corresponding command-line option. + NOTE: Due to some internal details in the current Boost.Build implementation it is not possible to have features whose valid values are all positive integer. As a workaround a large set of allowed values has been defined for this feature and, if a different one is needed, user can easily add it by calling the feature.extend rule. [[bbv2.builtin.features.embed-manifest]]`embed-manifest`:: *Allowed values:* `on`, `off`. + This feature is specific to the msvc toolset (see link:#bbv2.reference.tools.compiler.msvc[the section called “Microsoft Visual {CPP}”]), and controls whether the manifest files should be embedded inside executables and shared libraries, or placed alongside them. This feature corresponds to the IDE option found in the project settings dialog, under Configuration Properties -> Manifest Tool -> Input and Output -> Embed manifest. [[bbv2.builtin.features.embed-manifest-file]]`embed-manifest-file`:: This feature is specific to the msvc toolset (see link:#bbv2.reference.tools.compiler.msvc[the section called “Microsoft Visual {CPP}”]), and controls which manifest files should be embedded inside executables and shared libraries. This feature corresponds to the IDE option found in the project settings dialog, under Configuration Properties -> Manifest Tool -> Input and Output -> Additional Manifest Files. [[bbv2.builtin.features.relevant]]`relevant`:: *Allowed values:* the name of any feature. + This feature is used to indicate which other features are relevant for a given target. It is usually not necessary to manage it explicitly, as Boost.Build can deduce it in most cases. Features which are not relevant will not affect target paths, and will not cause conflicts. + * A feature will be considered relevant if any of the following are true + ** It is referenced by `toolset.flags` or `toolset.uses-features` ** It is used by the requirements of a generator ** It is a sub-feature of a relevant feature ** It has a sub-feature which is relevant ** It is a composite feature, and any composed feature is relevant ** It affects target alternative selection for a main target ** It is a propagated feature and is relevant for any dependency ** It is relevant for any dependency created by the same main target ** It is used in the condition of a conditional property and the corresponding value is relevant ** It is explicitly named as relevant + * Relevant features cannot be automatically deduced in the following cases: + ** Indirect conditionals. Solution: return properties of the form `result-feature:condition-feature` + NOTE: This isn't really a conditional, although for most purposes it functions like one. In particular, it does not support multiple comma-separated elements in the condition, and it does work correctly even in contexts where conditional properties are not allowed ** Action rules that read properties. Solution: add toolset.uses-features to tell Boost.Build that the feature is actually used. ** Generators and targets that manipulate property-sets directly. Solution: set manually. [[bbv2.builtin.features.visibility]]`visibility`:: *Allowed values:* `global`, `protected`, `hidden`. + This feature is used to specify the default symbol visibility in compiled binaries. Not all values are supported on all platforms and on some platforms (for example, Windows) symbol visibility is not supported at all. + The supported values have the following meaning: + * `global` - a.k.a. "default" in gcc documentation. Global symbols are considered public, they are exported from shared libraries and can be redefined by another shared library or executable. * `protected` - a.k.a. "symbolic". Protected symbols are exported from shared libraries but cannot be redefined by another shared library or executable. This mode is not supported on some platforms, for example OS X. * `hidden` - Hidden symbols are not exported from shared libraries and cannot be redefined by a different shared library or executable loaded in a process. In this mode, public symbols have to be explicitly marked in the source code to be exported from shared libraries. This is the recommended mode. + By default compiler default visibility mode is used (no compiler flags are added). + NOTE: In Boost superproject Jamroot file this property is set to the default value of `hidden`. This means that Boost libraries are built with hidden visibility by default, unless the user overrides it with a different `visibility` or a library sets a different `local-visibility` (see below). [[bbv2.builtin.features.local-visibility]]`local-visibility`:: *Allowed values:* `global`, `protected`, `hidden`. + This feature has the same effect as the `visibility` feature but is intended to be used by targets that require a particular symbol visibility. Unlike the `visibility` feature, `local-visibility` is not inherited by the target dependencies and only affects the target to which it is applied. + The `local-visibility` feature supports the same values with the same meaning as the `visibility` feature. By default, if `local-visibility` is not specified for a target, the value of the `visibility` feature is used. [[bbv2.reference.tools]] == Builtin tools Boost.Build comes with support for a large number of {CPP} compilers, and other tools. This section documents how to use those tools. Before using any tool, you must declare your intention, and possibly specify additional information about the tool's configuration. This is done by calling the `using` rule, typically in your `user-config.jam`, for example: [source] ---- using gcc ; ---- additional parameters can be passed just like for other rules, for example: [source] ---- using gcc : 4.0 : g++-4.0 ; ---- The options that can be passed to each tool are documented in the subsequent sections. [[bbv2.reference.tools.compilers]] === {CPP} Compilers This section lists all Boost.Build modules that support {CPP} compilers and documents how each one can be initialized. The name of support module for compiler is also the value for the `toolset` feature that can be used to explicitly request that compiler. :leveloffset: +3 include::../../src/tools/acc.jam[tag=doc] include::../../src/tools/borland.jam[tag=doc] include::../../src/tools/como.jam[tag=doc] include::../../src/tools/cw.jam[tag=doc] include::../../src/tools/dmc.jam[tag=doc] include::../../src/tools/gcc.jam[tag=doc] include::../../src/tools/hp_cxx.jam[tag=doc] include::../../src/tools/intel.jam[tag=doc] include::../../src/tools/msvc.jam[tag=doc] include::../../src/tools/sun.jam[tag=doc] include::../../src/tools/vacpp.jam[tag=doc] :leveloffset: -3 === Third-party libraries Boost.Build provides special support for some third-party {CPP} libraries, documented below. [[bbv2.reference.tools.libraries.stlport]] ==== STLport library The http://stlport.org[STLport] library is an alternative implementation of {CPP} runtime library. Boost.Build supports using that library on Windows platform. Linux is hampered by different naming of libraries in each STLport version and is not officially supported. Before using STLport, you need to configure it in `user-config.jam` using the following syntax: [source] ---- using stlport : version : header-path : library-path ; ---- Where version is the version of STLport, for example `5.1.4`, headers is the location where STLport headers can be found, and libraries is the location where STLport libraries can be found. The version should always be provided, and the library path should be provided if you're using STLport's implementation of `iostreams`. Note that STLport 5.* always uses its own `iostream` implementation, so the library path is required. When STLport is configured, you can build with STLport by requesting `stdlib=stlport` on the command line. [[bbv2.reference.tools.libraries.zlib]] ==== zlib Provides support for the http://www.zlib.net[zlib] library. zlib can be configured either to use precompiled binaries or to build the library from source. zlib can be initialized using the following syntax [source] ---- using zlib : version : options : condition : is-default ; ---- Options for using a prebuilt library: `search`:: The directory containing the zlib binaries. `name`:: Overrides the default library name. `include`:: The directory containing the zlib headers. If none of these options is specified, then the environmental variables ZLIB_LIBRARY_PATH, ZLIB_NAME, and ZLIB_INCLUDE will be used instead. Options for building zlib from source: `source`:: The zlib source directory. Defaults to the environmental variable ZLIB_SOURCE. `tag`:: Sets the link:#bbv2.builtin.features.tag[tag] property to adjust the file name of the library. Ignored when using precompiled binaries. `build-name`:: The base name to use for the compiled library. Ignored when using precompiled binaries. Examples: [source] ---- # Find zlib in the default system location using zlib ; # Build zlib from source using zlib : 1.2.7 : /home/steven/zlib-1.2.7 ; # Find zlib in /usr/local using zlib : 1.2.7 : /usr/local/include /usr/local/lib ; # Build zlib from source for msvc and find # prebuilt binaries for gcc. using zlib : 1.2.7 : C:/Devel/src/zlib-1.2.7 : msvc ; using zlib : 1.2.7 : : gcc ; ---- [[bbv2.reference.tools.libraries.bzip2]] ==== bzip2 Provides support for the http://www.bzip.org[bzip2] library. bzip2 can be configured either to use precompiled binaries or to build the library from source. bzip2 can be initialized using the following syntax [source] ---- using bzip2 : version : options : condition : is-default ; ---- Options for using a prebuilt library: `search`:: The directory containing the bzip2 binaries. `name`:: Overrides the default library name. `include`:: The directory containing the bzip2 headers. If none of these options is specified, then the environmental variables BZIP2_LIBRARY_PATH, BZIP2_NAME, and BZIP2_INCLUDE will be used instead. Options for building bzip2 from source: `source`:: The bzip2 source directory. Defaults to the environmental variable BZIP2_SOURCE. `tag`:: Sets the link:#bbv2.builtin.features.tag[tag] property to adjust the file name of the library. Ignored when using precompiled binaries. `build-name`:: The base name to use for the compiled library. Ignored when using precompiled binaries. Examples: [source] ---- # Find bzip in the default system location using bzip2 ; # Build bzip from source using bzip2 : 1.0.6 : /home/sergey/src/bzip2-1.0.6 ; # Find bzip in /usr/local using bzip2 : 1.0.6 : /usr/local/include /usr/local/lib ; # Build bzip from source for msvc and find # prebuilt binaries for gcc. using bzip2 : 1.0.6 : C:/Devel/src/bzip2-1.0.6 : msvc ; using bzip2 : 1.0.6 : : gcc ; ---- [[bbv2.reference.tools.libraries.python]] ==== Python Provides support for the http://www.python.org[python] language environment to be linked in as a library. python can be initialized using the following syntax [source] ---- using python : [version] : [command-or-prefix] : [includes] : [libraries] : [conditions] : [extension-suffix] ; ---- Options for using python: `version`:: The version of Python to use. Should be in Major.Minor format, for example 2.3. Do not include the sub-minor version. `command-or-prefix`:: Preferably, a command that invokes a Python interpreter. Alternatively, the installation prefix for Python libraries and includes. If empty, will be guessed from the version, the platform's installation patterns, and the python executables that can be found in PATH. `includes`:: the include path to Python headers. If empty, will be guessed. `libraries`:: the path to Python library binaries. If empty, will be guessed. On MacOS/Darwin, you can also pass the path of the Python framework. `conditions`:: if specified, should be a set of properties that are matched against the build configuration when Boost.Build selects a Python configuration to use. `extension-suffix`:: A string to append to the name of extension modules before the true filename extension. Ordinarily we would just compute this based on the value of the `` feature. However ubuntu's `python-dbg` package uses the windows convention of appending _d to debug-build extension modules. We have no way of detecting ubuntu, or of probing python for the "_d" requirement, and if you configure and build python using `--with-pydebug`, you'll be using the standard *nix convention. Defaults to "" (or "_d" when targeting windows and is set). Examples: [source] ---- # Find python in the default system location using python ; # 2.7 using python : 2.7 ; # 3.5 using python : 3.5 ; # On ubuntu 16.04 using python : 2.7 # version : # Interpreter/path to dir : /usr/include/python2.7 # includes : /usr/lib/x86_64-linux-gnu # libs : # conditions ; using python : 3.5 # version : # Interpreter/path to dir : /usr/include/python3.5 # includes : /usr/lib/x86_64-linux-gnu # libs : # conditions ; # On windows using python : 2.7 # version : C:\\Python27-32\\python.exe # Interperter/path to dir : C:\\Python27-32\\include # includes : C:\\Python27-32\\libs # libs : 32 # conditions - both 32 and unspecified ; using python : 2.7 # version : C:\\Python27-64\\python.exe # Interperter/path to dir : C:\\Python27-64\\include # includes : C:\\Python27-64\\libs # libs : 64 # conditions ; ---- === Documentation tools Boost.Build support for the Boost documentation tools is documented below. [[bbv2.reference.tools.doc.xsltproc]] ==== xsltproc To use xsltproc, you first need to configure it using the following syntax: [source] ---- using xsltproc : xsltproc ; ---- Where xsltproc is the xsltproc executable. If xsltproc is not specified, and the variable XSLTPROC is set, the value of XSLTPROC will be used. Otherwise, xsltproc will be searched for in PATH. The following options can be provided, using _`option-value syntax`_: `xsl:param`:: Values should have the form name=value `xsl:path`:: Sets an additional search path for xi:include elements. `catalog`:: A catalog file used to rewrite remote URL's to a local copy. The xsltproc module provides the following rules. Note that these operate on jam targets and are intended to be used by another toolset, such as boostbook, rather than directly by users. `xslt`:: + ---- rule xslt ( target : source stylesheet : properties * ) ---- + Runs xsltproc to create a single output file. `xslt-dir`:: + ---- rule xslt-dir ( target : source stylesheet : properties * : dirname ) ---- + Runs xsltproc to create multiple outputs in a directory. `dirname` is unused, but exists for historical reasons. The output directory is determined from the target. [[bbv2.reference.tools.doc.boostbook]] ==== boostbook To use boostbook, you first need to configure it using the following syntax: [source] ---- using boostbook : docbook-xsl-dir : docbook-dtd-dir : boostbook-dir ; ---- `docbook-xsl-dir` is the DocBook XSL stylesheet directory. If not provided, we use `DOCBOOK_XSL_DIR` from the environment (if available) or look in standard locations. Otherwise, we let the XML processor load the stylesheets remotely. `docbook-dtd-dir` is the DocBook DTD directory. If not provided, we use `DOCBOOK_DTD_DIR` From the environment (if available) or look in standard locations. Otherwise, we let the XML processor load the DTD remotely. `boostbook-dir` is the BoostBook directory with the DTD and XSL sub-dirs. The boostbook module depends on xsltproc. For pdf or ps output, it also depends on fop. The following options can be provided, using _`option-value syntax`_: `format`:: + *Allowed values:* `html`, `xhtml`, `htmlhelp`, `onehtml`, `man`, `pdf`, `ps`, `docbook`, `fo`, `tests`. + The `format` feature determines the type of output produced by the boostbook rule. The boostbook module defines a rule for creating a target following the common syntax. `boostbook`:: + ---- rule boostbook ( target-name : sources * : requirements * : default-build * ) ---- + Creates a boostbook target. [[bbv2.reference.tools.doc.doxygen]] ==== doxygen To use doxygen, you first need to configure it using the following syntax: [source] ---- using doxygen : name ; ---- `name` is the doxygen command. If it is not specified, it will be found in the PATH. The doxygen module depends on the boostbook module when generating BoostBook XML. The following options can be provided, using _`option-value syntax`_: `doxygen:param`:: + All the values of `doxygen:param` are added to the `doxyfile`. `prefix`:: + Specifies the common prefix of all headers when generating BoostBook XML. Everything before this will be stripped off. `reftitle`:: + Specifies the title of the library-reference section, when generating BoostBook XML. `doxygen:xml-imagedir`:: + When generating BoostBook XML, specifies the directory in which to place the images generated from LaTex formulae. + WARNING: The path is interpreted relative to the current working directory, not relative to the Jamfile. This is necessary to match the behavior of BoostBook. The doxygen module defines a rule for creating a target following the common syntax. `doxygen`:: + ---- rule doxygen ( target : sources * : requirements * : default-build * : usage-requirements * ) ---- + Creates a doxygen target. If the target name ends with .html, then this will generate an html directory. Otherwise it will generate BoostBook XML. [[bbv2.reference.tools.doc.quickbook]] ==== quickbook The quickbook module provides a generator to convert from Quickbook to BoostBook XML. To use quickbook, you first need to configure it using the following syntax: [source] ---- using quickbook : command ; ---- `command` is the quickbook executable. If it is not specified, Boost.Build will compile it from source. If it is unable to find the source it will search for a quickbook executable in PATH. [[bbv2.reference.tools.doc.fop]] ==== fop The fop module provides generators to convert from XSL formatting objects to Postscript and PDF. To use fop, you first need to configure it using the following syntax: [source] ---- using fop : fop-command : java-home : java ; ---- `fop-command` is the command to run fop. If it is not specified, Boost.Build will search for it in PATH and FOP_HOME. Either `java-home` or `java` can be used to specify where to find java. [[bbv2.reference.modules]] == Builtin modules This section describes the modules that are provided by Boost.Build. The import rule allows rules from one module to be used in another module or Jamfile. [[bbv2.reference.modules.modules]] === modules The `modules` module defines basic functionality for handling modules. A module defines a number of rules that can be used in other modules. Modules can contain code at the top level to initialize the module. This code is executed the first time the module is loaded. NOTE: A Jamfile is a special kind of module which is managed by the build system. Although they cannot be loaded directly by users, the other features of modules are still useful for Jamfiles. Each module has its own namespaces for variables and rules. If two modules A and B both use a variable named X, each one gets its own copy of X. They won't interfere with each other in any way. Similarly, importing rules into one module has no effect on any other module. Every module has two special variables. `$(__file__)` contains the name of the file that the module was loaded from and `$(__name__)` contains the name of the module. NOTE: `$(__file__)` does not contain the full path to the file. If you need this, use `modules.binding`. 1. `rule binding ( module-name )` + Returns the filesystem binding of the given module. + For example, a module can get its own location with: + [source,jam] ---- me = [ modules.binding $(__name__) ] ; ---- 2. `rule poke ( module-name ? : variables + : value * )` + Sets the module-local value of a variable. + For example, to set a variable in the global module: + [source,jam] ---- modules.poke : ZLIB_INCLUDE : /usr/local/include ; ---- 3. `rule peek ( module-name ? : variables + )` + Returns the module-local value of a variable. + For example, to read a variable from the global module: + [source,jam] ---- local ZLIB_INCLUDE = [ modules.peek : ZLIB_INCLUDE ] ; ---- 4. `rule call-in ( module-name ? : rule-name args * : * )` + Call the given rule locally in the given module. Use this for rules accepting rule names as arguments, so that the passed rule may be invoked in the context of the rule's caller (for example, if the rule accesses module globals or is a local rule). + NOTE: rules called this way may accept at most 8 parameters. + Example: + [source,jam] ---- rule filter ( f : values * ) { local m = [ CALLER_MODULE ] ; local result ; for v in $(values) { if [ modules.call-in $(m) : $(f) $(v) ] { result += $(v) ; } } return result ; } ---- 5. `rule load ( module-name : filename ? : search * )` + Load the indicated module if it is not already loaded. + `module-name`:: Name of module to load. + `filename`:: (partial) path to file; Defaults to `$(module-name).jam` + `search`:: Directories in which to search for filename. Defaults to `$(BOOST_BUILD_PATH)`. 6. `rule import ( module-names + : rules-opt * : rename-opt * )` + Load the indicated module and import rule names into the current module. Any members of `rules-opt` will be available without qualification in the caller's module. Any members of `rename-opt` will be taken as the names of the rules in the caller's module, in place of the names they have in the imported module. If `rules-opt = '*'`, all rules from the indicated module are imported into the caller's module. If `rename-opt` is supplied, it must have the same number of elements as `rules-opt`. + NOTE: The `import` rule is available without qualification in all modules. + Examples: + [source,jam] ---- import path ; import path : * ; import path : join ; import path : native make : native-path make-path ; ---- 7. `rule clone-rules ( source-module target-module )` + Define exported copies in `$(target-module)` of all rules exported from `$(source-module)`. Also make them available in the global module with qualification, so that it is just as though the rules were defined originally in `$(target-module)`. :leveloffset: +2 include::path.adoc[] include::regex.adoc[] include::sequence.adoc[] include::type.adoc[] :leveloffset: -2 [[bbv2.reference.class]] == Builtin classes :leveloffset: +2 include::abstract-target.adoc[] include::project-target.adoc[] include::main-target.adoc[] include::basic-target.adoc[] include::typed-target.adoc[] include::property-set.adoc[] :leveloffset: -2 [[bbv2.reference.buildprocess]] == Build process The general overview of the build process was given in the link:#bbv2.overview.build_process[user documentation]. This section provides additional details, and some specific rules. To recap, building a target with specific properties includes the following steps: 1. applying the default build, 2. selecting the main target alternative to use, 3. determining the "common" properties, 4. building targets referred by the the sources list and dependency properties, 5. adding the usage requirements produced when building dependencies to the "common" properties, 6. building the target using generators, 7. computing the usage requirements to be returned. [[bbv2.reference.buildprocess.alternatives]] === Alternative selection When a target has several alternatives, one of them must be selected. The process is as follows: 1. For each alternative, its _condition_ is defined as the set of link:#bbv2.reference.features.attributes.base[base properties] in its requirements. link:#bbv2.reference.variants.propcond[Conditional properties] are excluded. 2. An alternative is viable only if all properties in its condition are present in the build request. 3. If there's only one viable alternative, it's chosen. Otherwise, an attempt is made to find the best alternative. An alternative a is better than another alternative b, if the set of properties in b's condition is a strict subset of the set of properties of a's condition. If one viable alternative is better than all the others, it's selected. Otherwise, an error is reported. [[bbv2.reference.buildprocess.common]] === Determining common properties "Common" properties is a somewhat artificial term. This is the intermediate property set from which both the build request for dependencies and the properties for building the target are derived. Since the default build and alternatives are already handled, we have only two inputs: the build request and the requirements. Here are the rules about common properties. 1. Non-free features can have only one value 2. A non-conditional property in the requirements is always present in common properties. 3. A property in the build request is present in common properties, unless it is overridden by a property in the requirements. 4. If either the build request, or the requirements (non-conditional or conditional) include an expandable property (either composite, or with a specified sub-feature value), the behavior is equivalent to explicitly adding all the expanded properties to the build request or the requirements respectively. 5. If the requirements include a link:#bbv2.reference.variants.propcond[conditional property], and the condition of this property is true in the context of common properties, then the conditional property should be in common properties as well. 6. If no value for a feature is given by other rules here, it has default value in common properties. These rules are declarative. They don't specify how to compute the common properties. However, they provide enough information for the user. The important point is the handling of conditional requirements. The condition can be satisfied either by a property in the build request, by non-conditional requirements, or even by another conditional property. For example, the following example works as expected: [source] ---- exe a : a.cpp : gcc:release release:FOO ; ---- [[bbv2.reference.buildprocess.targetpath]] === Target Paths Several factors determine the location of a concrete file target. All files in a project are built under the directory bin unless this is overridden by the build-dir project attribute. Under bin is a path that depends on the properties used to build each target. This path is uniquely determined by all non-free, non-incidental properties. For example, given a property set containing: `gcc` `4.6.1` `debug` `all` `_DEBUG` `/usr/local/include` `static`, the path will be `gcc-4.6.1/debug/link-static`. `` is an incidental feature and `` and `` are free features, so they do not affect the path. Sometimes the paths produced by Boost.Build can become excessively long. There are a couple of command line options that can help with this. `--abbreviate-paths` reduces each element to no more than five characters. For example, `link-static` becomes `lnk-sttc`. The `--hash` option reduces the path to a single directory using an MD5 hash. There are two features that affect the build directory. The `` feature completely overrides the default build directory. For example, [source] ---- exe a : a.cpp : . ; ---- builds all the files produced by `a` in the directory of the Jamfile. This is generally discouraged, as it precludes variant builds. The feature adds a prefix to the path, under the project's build directory. For example, [source] ---- exe a : a.cpp : subdir ; ---- will create the files for `a` in `bin/subdir/gcc-4.6.1/debug` [[bbv2.reference.definitions]] == Definitions [[bbv2.reference.features]] === Features and properties A _feature_ is a normalized (toolset-independent) aspect of a build configuration, such as whether inlining is enabled. Feature names may not contain the '`>`' character. Each feature in a build configuration has one or more associated __value__s. Feature values for non-free features may not contain the punctuation characters of pointy bracket (‘`<`’), colon (‘`:`’ ), equal sign (‘`=`’) and dashes (‘`-`’). Feature values for free features may not contain the pointy bracket (‘`<`’) character. A _property_ is a (feature,value) pair, expressed as value. A _subfeature_ is a feature that only exists in the presence of its parent feature, and whose identity can be derived (in the context of its parent) from its value. A subfeature's parent can never be another subfeature. Thus, features and their subfeatures form a two-level hierarchy. A _value-string_ for a feature *F* is a string of the form `value-subvalue1-subvalue2`...`-subvalueN`, where `value` is a legal value for *F* and `subvalue1`...`subvalueN` are legal values of some of *F*'s subfeatures separated with dashes (‘`-`’). For example, the properties `gcc 3.0.1` can be expressed more concisely using a value-string, as `gcc-3.0.1`. A _property set_ is a set of properties (i.e. a collection without duplicates), for instance: `gcc static`. A _property path_ is a property set whose elements have been joined into a single string separated by slashes. A property path representation of the previous example would be `gcc/static`. A _build specification_ is a property set that fully describes the set of features used to build a target. [[bbv2.reference.features.validity]] === Property Validity For link:#bbv2.reference.features.attributes.free[free] features, all values are valid. For all other features, the valid values are explicitly specified, and the build system will report an error for the use of an invalid feature-value. Subproperty validity may be restricted so that certain values are valid only in the presence of certain other subproperties. For example, it is possible to specify that the `mingw` property is only valid in the presence of `2.95.2`. [[bbv2.reference.features.attributes]] === Feature Attributes Each feature has a collection of zero or more of the following attributes. Feature attributes are low-level descriptions of how the build system should interpret a feature's values when they appear in a build request. We also refer to the attributes of properties, so that an _incidental_ property, for example, is one whose feature has the _incidental_ attribute. * [[bbv2.reference.features.attributes.incidental]] _incidental_ + Incidental features are assumed not to affect build products at all. As a consequence, the build system may use the same file for targets whose build specification differs only in incidental features. A feature that controls a compiler's warning level is one example of a likely incidental feature. + Non-incidental features are assumed to affect build products, so the files for targets whose build specification differs in non-incidental features are placed in different directories as described in <>. * [[bbv2.reference.features.attributes.propagated]] _propagated_ + Features of this kind are propagated to dependencies. That is, if a link:#bbv2.overview.targets.main[main target] is built using a propagated property, the build systems attempts to use the same property when building any of its dependencies as part of that main target. For instance, when an optimized executable is requested, one usually wants it to be linked with optimized libraries. Thus, the `` feature is propagated. * [[bbv2.reference.features.attributes.free]] _free_ + Most features have a finite set of allowed values, and can only take on a single value from that set in a given build specification. Free features, on the other hand, can have several values at a time and each value can be an arbitrary string. For example, it is possible to have several preprocessor symbols defined simultaneously: + ---- NDEBUG=1 HAS_CONFIG_H=1 ---- * [[bbv2.reference.features.attributes.optional]] _optional_ + An optional feature is a feature that is not required to appear in a build specification. Every non-optional non-free feature has a default value that is used when a value for the feature is not otherwise specified, either in a target's requirements or in the user's build request. [A feature's default value is given by the first value listed in the feature's declaration. -- move this elsewhere - dwa] * [[bbv2.reference.features.attributes.symmetric]] _symmetric_ + Normally a feature only generates a sub-variant directory when its value differs from its default value, leading to an asymmetric sub-variant directory structure for certain values of the feature. A symmetric feature always generates a corresponding sub-variant directory. * [[bbv2.reference.features.attributes.path]] _path_ + The value of a path feature specifies a path. The path is treated as relative to the directory of Jamfile where path feature is used and is translated appropriately by the build system when the build is invoked from a different directory * [[bbv2.reference.features.attributes.implicit]] _implicit_ + Values of implicit features alone identify the feature. For example, a user is not required to write "gcc", but can simply write "gcc". Implicit feature names also don't appear in variant paths, although the values do. Thus: bin/gcc/... as opposed to bin/toolset-gcc/.... There should typically be only a few such features, to avoid possible name clashes. * [[bbv2.reference.features.attributes.composite]] _composite_ + Composite features actually correspond to groups of properties. For example, a build variant is a composite feature. When generating targets from a set of build properties, composite features are recursively expanded and _added_ to the build property set, so rules can find them if necessary. Non-composite non-free features override components of composite features in a build property set. * [[bbv2.reference.features.attributes.dependency]] _dependency_ + The value of a dependency feature is a target reference. When used for building of a main target, the value of dependency feature is treated as additional dependency. + For example, dependency features allow to state that library A depends on library B. As the result, whenever an application will link to A, it will also link to B. Specifying B as dependency of A is different from adding B to the sources of A. [[bbv2.reference.features.attributes.base]] Features that are neither free nor incidental are called _base_ features. [[bbv2.reference.features.declaration]] === Feature Declaration The low-level feature declaration interface is the `feature` rule from the `feature` module: [source] ---- rule feature ( name : allowed-values * : attributes * ) ---- A feature's allowed-values may be extended with the `feature.extend` rule. [[bbv2.reference.variants.proprefine]] === Property refinement When a target with certain properties is requested, and that target requires some set of properties, it is needed to find the set of properties to use for building. This process is called _property refinement_ and is performed by these rules 1. Each property in the required set is added to the original property set 2. If the original property set includes property with a different value of non free feature, that property is removed. [[bbv2.reference.variants.propcond]] === Conditional properties Sometime it's desirable to apply certain requirements only for a specific combination of other properties. For example, one of compilers that you use issues a pointless warning that you want to suppress by passing a command line option to it. You would not want to pass that option to other compilers. Conditional properties allow you to do just that. Their syntax is: ---- property ( "," property ) * ":" property ---- For example, the problem above would be solved by: [source] ---- exe hello : hello.cpp : yfc:-disable-pointless-warning ; ---- The syntax also allows several properties in the condition, for example: [source] ---- exe hello : hello.cpp : NT,gcc:static ; ---- [[bbv2.reference.ids]] === Target identifiers and references _Target identifier_ is used to denote a target. The syntax is: ---- target-id -> (target-name | file-name | project-id | directory-name) | (project-id | directory-name) "//" target-name project-id -> path target-name -> path file-name -> path directory-name -> path ---- This grammar allows some elements to be recognized as either * name of target declared in current Jamfile (note that target names may include slash). * a regular file, denoted by absolute name or name relative to project's sources location. * project id (at this point, all project ids start with slash). * the directory of another project, denoted by absolute name or name relative to the current project's location. To determine the real meaning the possible interpretations are checked in this order. For example, valid target ids might be: |=== | `a` | target in current project | `lib/b.cpp` | regular file | `/boost/thread` | project "/boost/thread" | `/home/ghost/build/lr_library//parser` | target in specific project | `../boost_1_61_0` | project in specific directory |=== **Rationale:**Target is separated from project by special separator (not just slash), because: * It emphasis that projects and targets are different things. * It allows to have main target names with slashes. [[bbv2.reference.targets.references]] _Target reference_ is used to specify a source target, and may additionally specify desired properties for that target. It has this syntax: ---- target-reference -> target-id [ "/" requested-properties ] requested-properties -> property-path ---- For example, [source] ---- exe compiler : compiler.cpp libs/cmdline/space ; ---- would cause the version of `cmdline` library, optimized for space, to be linked in even if the `compiler` executable is build with optimization for speed.