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'coercion_experiments'.

[SVN r8021]
This commit is contained in:
nobody
2000-10-20 02:25:42 +00:00
parent 261a4e63d2 6a7455b528
commit 6b0144ef31
48 changed files with 3429 additions and 507 deletions
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62
extclass.cpp
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@@ -157,7 +157,7 @@ void report_missing_instance_data(
}
else
{
two_string_error(PyExc_TypeError, "extension class '%.*s' is not derived from '%.*s'.",
two_string_error(PyExc_TypeError, "extension class '%.*s' is not convertible into '%.*s'.",
instance->ob_type->tp_name, target_class->tp_name);
}
}
@@ -218,6 +218,66 @@ ExtensionClassBase::ExtensionClassBase(const char* name)
{
}
// This function is used in from_python() to convert wrapped classes that are
// related by inheritance. The problem is this: although C++ provides all necessary
// conversion operators, source and target of a conversion must be known at compile
// time. However, in Python we want to convert classes at runtime. The solution is to
// generate conversion functions at compile time, register them within the appropriate
// class objects and call them when a particular runtime conversion is required.
// If functions for any possible conversion have to be stored, their number will grow
// qudratically. To reduce this number, we actually store only conversion functions
// between adjacent levels in the inheritance tree. By traversing the tree recursively,
// we can build any allowed conversion as a concatenation of simple conversions. This
// traversal is done in the functions try_base_class_conversions() and
// try_derived_class_conversions(). If a particular conversion is impossible, all
// conversion functions will return a NULL pointer.
// The function extract_object_from_holder() attempts to actually extract the pointer
// to the contained object from an InstanceHolderBase (a wrapper class). A conversion
// of the held object to 'T *' is allowed when the conversion
// 'dynamic_cast<InstanceHolder<T> *>(an_instance_holder_base)' succeeds.
void* ExtensionClassBase::try_class_conversions(InstanceHolderBase* object) const
{
void* result = try_derived_class_conversions(object);
if(result)
return result;
return try_base_class_conversions(object);
}
void* ExtensionClassBase::try_base_class_conversions(InstanceHolderBase* object) const
{
for (std::size_t i = 0; i < base_classes().size(); ++i)
{
if(base_classes()[i].convert == 0)
continue;
void* result1 = base_classes()[i].class_object->extract_object_from_holder(object);
if (result1)
return (*base_classes()[i].convert)(result1);
void* result2 = base_classes()[i].class_object->try_base_class_conversions(object);
if (result2)
return (*base_classes()[i].convert)(result2);
}
return 0;
}
void* ExtensionClassBase::try_derived_class_conversions(InstanceHolderBase* object) const
{
for (std::size_t i = 0; i < derived_classes().size(); ++i)
{
void* result1 = derived_classes()[i].class_object->extract_object_from_holder(object);
if (result1)
return (*derived_classes()[i].convert)(result1);
void* result2 = derived_classes()[i].class_object->try_derived_class_conversions(object);
if (result2)
return (*derived_classes()[i].convert)(result2);
}
return 0;
}
void ExtensionClassBase::add_method(Function* method, const char* name)
{
add_method(PyPtr<Function>(method), name);