pygccxml-development

[pygccxml-development] Question about calldef_wrapper_t.argument_name()

[Matthias B. <ba...@ir...>]

Hi,

while going through the Py++ sources I wondered about the method 
argument_name() in class calldef_wrapper_t. Here is its definition:

     def argument_name( self, index ):
         arg = self.declaration.arguments[ index ]
         if arg.name:
             return arg.name
         else:
             return 'p%d' % index

What I wondered is if the 'else' block is ever reached? I searched in 
scanner.py where the argument_t class is actually used and found this:

     argument = argument_t()
     argument.name = attrs.get( XML_AN_NAME, 'arg%d' % 
len(self.__inst.arguments) )

So the name can only be empty if gccxml reports it as such. I don't know 
if this can ever happen or not, but even if it can happen, why is the 
test from calldef_wrapper_t not moved to the scanner? For example:

    if not argument.name:
       argument.name = 'arg%d' % len(self.__inst.arguments)

Then an argument_t object read from a C++ file would always have a valid 
name and the method argument_name() wouldn't be required anymore (and 
other parts of the code would actually also be able to know the name of 
an argument).

To be on the safe side, the _get_name() method of argument_t could also 
create a name if the argument doesn't already have a valid name.

- Matthias -

Re: [pygccxml-development] Question about calldef_wrapper_t.argument_name()

[Roman Y. <rom...@gm...>]

On 9/14/06, Matthias Baas <ba...@ir...> wrote:
> Hi,
>
> while going through the Py++ sources I wondered about the method
> argument_name() in class calldef_wrapper_t. Here is its definition:
>
>      def argument_name( self, index ):
>          arg = self.declaration.arguments[ index ]
>          if arg.name:
>              return arg.name
>          else:
>              return 'p%d' % index
>
> What I wondered is if the 'else' block is ever reached? I searched in
> scanner.py where the argument_t class is actually used and found this:
>
>      argument = argument_t()
>      argument.name = attrs.get( XML_AN_NAME, 'arg%d' %
> len(self.__inst.arguments) )
>
> So the name can only be empty if gccxml reports it as such. I don't know
> if this can ever happen or not, but even if it can happen, why is the
> test from calldef_wrapper_t not moved to the scanner? For example:
>
>     if not argument.name:
>        argument.name = 'arg%d' % len(self.__inst.arguments)
>
> Then an argument_t object read from a C++ file would always have a valid
> name and the method argument_name() wouldn't be required anymore (and
> other parts of the code would actually also be able to know the name of
> an argument).

You can not do it. If you set argument names from the scanner, than Py++
will generate wrong code - keyword arguments. Take a look on
code_creators.calldef_t.keywords_args method. Now the answer to your
question
should be clear. In order to call function I have to pass arguments to
it, so I just created names for them.

-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/

Re: [pygccxml-development] Question about calldef_wrapper_t.argument_name()

[Matthias B. <ba...@ir...>]

Roman Yakovenko wrote:
>> So the name can only be empty if gccxml reports it as such. I don't know
>> if this can ever happen or not, but even if it can happen, why is the
>> test from calldef_wrapper_t not moved to the scanner? For example:
>>
>>     if not argument.name:
>>        argument.name = 'arg%d' % len(self.__inst.arguments)
>>
>> Then an argument_t object read from a C++ file would always have a valid
>> name and the method argument_name() wouldn't be required anymore (and
>> other parts of the code would actually also be able to know the name of
>> an argument).
> 
> You can not do it. If you set argument names from the scanner, than Py++
> will generate wrong code - keyword arguments. Take a look on
> code_creators.calldef_t.keywords_args method. Now the answer to your
> question should be clear. 

Uhm, well, sorry, it didn't get clear. What part of keywords_args() 
depends on gccxml producing empty strings? This method just uses the 
'name' attribute without checking if it is empty or not:

       result.append( '("%s")' % arg.name )

But if arg.name is empty, the wrapper code creator replaces it with 
p0,p1,p2, etc. So shouldn't keywords_args() do the same thing instead of 
leaving the string empty? (which is not a valid name for a keyword 
argument anyway)

- Matthias -