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Files
python/gen_callback.py
2000-11-17 19:58:31 +00:00

125 lines
3.8 KiB
Python

from gen_function import *
import string
def gen_callback(args):
return (
"""// (C) Copyright David Abrahams 2000. Permission to copy, use, modify, sell and
// distribute this software is granted provided this copyright notice appears
// in all copies. This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
// The author gratefully acknowleges the support of Dragon Systems, Inc., in
// producing this work.
//
// This file was generated for %d-argument python callbacks by gen_callback.py
#ifndef CALLBACK_DWA_052100_H_
# define CALLBACK_DWA_052100_H_
# include "pyconfig.h"
# include "py.h"
namespace py {
namespace detail {
template <class T>
inline void callback_adjust_refcount(PyObject*, Type<T>) {}
inline void callback_adjust_refcount(PyObject* p, Type<PyObject*>)
{ Py_INCREF(p); }
}
// Calling Python from C++
template <class R>
struct Callback
{""" % args
+ gen_functions('''
%{ template <%(class A%n%:, %)>
%} static R call_method(PyObject* self, const char* name%(, const A%n& a%n%))
{%(
Ptr p%n(to_python(a%n));%)
Ptr result(PyEval_CallMethod(self, const_cast<char*>(name),
const_cast<char*>("(%(O%))")%(,
p%n.get()%)));
detail::callback_adjust_refcount(result.get(), Type<R>());
return from_python(result.get(), Type<R>());
}
%{ template <%(class A%n%:, %)>
%} static R call(PyObject* self%(, const A%n& a%n%))
{%(
Ptr p%n(to_python(a%n));%)
Ptr result(PyEval_CallFunction(self, const_cast<char*>("(%(O%))")%(,
p%n.get()%)));
detail::callback_adjust_refcount(result.get(), Type<R>());
return from_python(result.get(), Type<R>());
}
''', args)
+
"""};
// This specialization wouldn't be needed, but MSVC6 doesn't correctly allow the following:
// void g();
// void f() { return g(); }
template <>
struct Callback<void>
{
"""
+ gen_functions('''
%{ template <%(class A%n%:, %)>
%} static void call_method(PyObject* self, const char* name%(, const A%n& a%n%))
{%(
Ptr p%n(to_python(a%n));%)
Ptr result(PyEval_CallMethod(self, const_cast<char*>(name),
const_cast<char*>("(%(O%))")%(,
p%n.get()%)));
}
%{ template <%(class A%n%:, %)>
%} static void call(PyObject* self%(, const A%n& a%n%))
{%(
Ptr p%n(to_python(a%n));%)
Ptr result(PyEval_CallFunction(self, const_cast<char*>("(%(O%))")%(,
p%n.get()%)));
}
''', args)
+
"""};
// Make it a compile-time error to try to return a const char* from a virtual
// function. The standard conversion
//
// from_python(PyObject* string, py::Type<const char*>)
//
// returns a pointer to the character array which is internal to string. The
// problem with trying to do this in a standard callback function is that the
// Python string would likely be destroyed upon return from the calling function
// (py::Callback<const char*>::call[_method]) when its reference count is
// decremented. If you absolutely need to do this and you're sure it's safe (it
// usually isn't), you can use
//
// py::String result(py::Callback<py::String>::call[_method](...args...));
// ...result.c_str()... // access the char* array
template <>
struct Callback<const char*>
{
// Try hard to generate a readable error message
typedef struct unsafe_since_python_string_may_be_destroyed {} call, call_method;
};
} // namespace py
#endif // CALLBACK_DWA_052100_H_
""")
if __name__ == '__main__':
import sys
if len(sys.argv) == 1:
args = 5
else:
args = int(sys.argv[1])
print gen_callback(args)