Re: [PyQt] downcast a base class to its template subclass

[Phil Thompson]

On Tue, 2 Nov 2010 10:55:51 -0700, Qin Shen  wrote:
> Hi Phil,
> 
> Phil Thompson wrote:
>> On Mon, 1 Nov 2010 17:26:41 -0700, Qin Shen 
wrote:
>>   
>>> Hi,
>>>
>>> In my non-template base class' .sip file, I used
%ConvertToSubClassCode 
>>> directive
>>> to downcast the base class type to its sub-class. If the sub-class is 
>>> not a template,
>>> it all works fine. Now I need to derive a template sub-class from the 
>>> base class,
>>> the sipFindType() won't work because there isn't any Python class 
>>> implemented
>>> for the templated sub-class. What should I do in this case?
>>> 
>>
>> So how is the template sub-class implemented in Python? Your
>> %ConvertToSubClassCode will need to explicitly check for the template
>> sub-class and return the appropriate Python type.
>>   
> The .sip file of the template sub-class is based on its C++ .h header
file.
> Its implementation in the .sip file has been omitted since I thought I 
> don't
> need to put any implementation in the .sip file as its C++ header file
has
> been properly included.
> 
> When you asked how is the template sub-class implemented in Python, did
you
> mean that I need to put the C++ style implementation in .sip as well?
> 
> Do I need to use %MappedType to convert the template sub-class to/from a

> Python
> type. For a non-template class, sip usually generates a .cpp file for it

> as well
> as a corresponding sipType_BLAH. In the case of a template class,
neither
> was generated. I don't see a direct type match between a Python type and
> any
> specialization of the template sub-class, and no sipType_ is generated
for
> the template class, how am I supposed to convert the type?

Any C++ template must eventually be implemented using a %MappedType -
that's where you decide what Python type will be used to represent the C++
type.

> Do you have any example on this?

There are lots of examples in PyQt - qlist.sip is probably the most
comprehensive.

Phil
___
PyQt mailing listPyQt@riverbankcomputing.com
http://www.riverbankcomputing.com/mailman/listinfo/pyqt

Re: [PyQt] downcast a base class to its template subclass

[Qin Shen]

Hi Phil,

Phil Thompson wrote:

On Mon, 1 Nov 2010 17:26:41 -0700, Qin Shen  wrote:
  

Hi,

In my non-template base class' .sip file, I used %ConvertToSubClassCode 
directive
to downcast the base class type to its sub-class. If the sub-class is 
not a template,
it all works fine. Now I need to derive a template sub-class from the 
base class,
the sipFindType() won't work because there isn't any Python class 
implemented

for the templated sub-class. What should I do in this case?



So how is the template sub-class implemented in Python? Your
%ConvertToSubClassCode will need to explicitly check for the template
sub-class and return the appropriate Python type.
  

The .sip file of the template sub-class is based on its C++ .h header file.
Its implementation in the .sip file has been omitted since I thought I 
don't

need to put any implementation in the .sip file as its C++ header file has
been properly included.

When you asked how is the template sub-class implemented in Python, did you
mean that I need to put the C++ style implementation in .sip as well?

Do I need to use %MappedType to convert the template sub-class to/from a 
Python
type. For a non-template class, sip usually generates a .cpp file for it 
as well

as a corresponding sipType_BLAH. In the case of a template class, neither
was generated. I don't see a direct type match between a Python type and any
specialization of the template sub-class, and no sipType_ is generated for
the template class, how am I supposed to convert the type?

Do you have any example on this?

Thanks a lot,

-Jean






___
PyQt mailing listPyQt@riverbankcomputing.com
http://www.riverbankcomputing.com/mailman/listinfo/pyqt

Re: [PyQt] downcast a base class to its template subclass

[Phil Thompson]

On Mon, 1 Nov 2010 17:26:41 -0700, Qin Shen  wrote:
> Hi,
> 
> In my non-template base class' .sip file, I used %ConvertToSubClassCode 
> directive
> to downcast the base class type to its sub-class. If the sub-class is 
> not a template,
> it all works fine. Now I need to derive a template sub-class from the 
> base class,
> the sipFindType() won't work because there isn't any Python class 
> implemented
> for the templated sub-class. What should I do in this case?
> 
> 
> The files look like this:
> 
> In [BaseEntity.sip]
> 
> class BaseEntity
> {
> %TypeHeaderCode
> #include 
> %End
> 
> %ConvertToSubClassCode
> sipType = sipFindType(sipCpp->classType());
> %End
> 
> public:
> 
> 
> }
> 
> 
> 
> [CustomEntity.h]
> ---
> template 
> class CustomEntity : BaseEntity
> {
> public:
> CustomEntity();
> virtual ~CustomEntity();
> 
> std::string classType() const
> {
> std::ostringstream nameStream;
> nameStream << "CustomEntity" << std::setfill('0') << 
> std::setw(2) << ID;
> return nameStream.str();
> }
> 
> ... // more stuff here
> }
> 
> 
> [CustomEntity.sip]
> ---
> template 
> class CustomEntity : BaseEntity
> {
> %TypeHeaderCode
> #include 
> %End
> 
> public:
> CustomEntity();
> virtual ~CustomEntity();
> 
> std::string classType() const;
> 
> ... // more stuff here
> }

So how is the template sub-class implemented in Python? Your
%ConvertToSubClassCode will need to explicitly check for the template
sub-class and return the appropriate Python type.

Phil
___
PyQt mailing listPyQt@riverbankcomputing.com
http://www.riverbankcomputing.com/mailman/listinfo/pyqt