Re: [Swig-user] typemap for polymorphic classes

[Charlie S. <cf...@sa...>]

Or look at %factory in the CHANGES files - its part of the unified type 
map library.


Charlie

William S Fulton wrote:
> James Bigler wrote:
>> Is it possible to define a typemap for polymorphic classes such that if 
>> you are supposed to return a base class you can return the actual class:
>>
>> class Parent {
>> };
>>
>> class GoodChild: public Parent {
>> };
>>
>> class BadChild: public Parent {
>> };
>>
>>
>> %typemap(out) Parent* {
>>    GoodChild* result = dynamic_cast<GoodChild*>($1);
>>    if (result) {
>>      // Wrap result in a swigged GoodChild
>>      $result = SWIG_NewPointerObj(SWIG_as_voidptr(result), 
>> SWIGTYPE_p_GoodChild, SWIG_POINTER_NEW | 0 );
>>    }
>>    BadChild* result = dynamic_cast<GoodChild*>($1);
>>    if (result) {
>>      // Wrap result in a swigged BadChild
>>      $result = SWIG_NewPointerObj(SWIG_as_voidptr(result), 
>> SWIGTYPE_p_BadChild, SWIG_POINTER_NEW | 0 );
>>    }
>>    // Don't know the type so return the base pointer
>>    $result = $1;
>> }
>>
>> Parent* foo(int type) {
>>    if (type == GOOD) {
>>      return new GoodChild();
>>    else
>>      return new BadChild();
>> }
>>
> 
> Read about DYNAMIC_CAST in the CHANGES file.
> 
> William
> 
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