pygccxml-development

[pygccxml-development] py++ generating invalid default args code

[Allen B. <al...@vr...>]

I am wrapping a method that looks something like this:

class MyClass
{
public:
   void init(const unsigned value=0,
             const ClassB valueb=ClassB(-10.0, 11.0),
             const float other_val=2.0);
};

When py++ wraps this it creates code like this:

{ //::MyClass::init

             typedef void ( ::MyClass::*init_function_type )( ::unsigned 
const,::ClassB const,::float const ) ;

         MyClass_exposer.def( "init"
         , init_function_type( &::MyClass::init )
         , (  bp::arg("value")=(unsigned char const)(0)
         , bp::arg("valueb")=::ClassB( (&-1.0e+1), (&1.1e+1)
         , bp::arg("other_val")=2.0e+0 ) );
}

As you can see the "&-1.0e+1" style values are invalid code and the 
compiler fails to build the code.  Is this a know issue and is there a 
simple work around or way to prevent py++ from generating code that 
won't compile?

Thanks,
Allen

PS. Sorry that I could not include the "real" sample, the code for it is 
internal use only.

Re: [pygccxml-development] py++ generating invalid default args code

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

On Jan 15, 2008 1:02 AM, Allen Bierbaum <al...@vr...> wrote:
> I am wrapping a method that looks something like this:
>
> class MyClass
> {
> public:
>    void init(const unsigned value=0,
>              const ClassB valueb=ClassB(-10.0, 11.0),
>              const float other_val=2.0);
> };
>
> When py++ wraps this it creates code like this:
>
> { //::MyClass::init
>
>              typedef void ( ::MyClass::*init_function_type )( ::unsigned
> const,::ClassB const,::float const ) ;
>
>          MyClass_exposer.def( "init"
>          , init_function_type( &::MyClass::init )
>          , (  bp::arg("value")=(unsigned char const)(0)
>          , bp::arg("valueb")=::ClassB( (&-1.0e+1), (&1.1e+1)
>          , bp::arg("other_val")=2.0e+0 ) );
> }
>
> As you can see the "&-1.0e+1" style values are invalid code and the
> compiler fails to build the code.  Is this a know issue and is there a
> simple work around or way to prevent py++ from generating code that
> won't compile?

Yes, this is a known issue -
http://language-binding.net/pygccxml/design.html#patchers

You have few ways to fix the problem:
http://language-binding.net/pyplusplus/documentation/functions/default_args.html
or
mb = module_builder_t(...)
mb.mem_fun( '::MyClass::init' ).arguments[1].default_value =
'ClassB(-10.0, 11.0)'

Choose the one you like

HTH

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

Re: [pygccxml-development] py++ generating invalid default args code

[Allen B. <al...@vr...>]

Is there a way to detect this problem is happening and output an error 
with a link to the documentation?  The way it works now where it 
generates code that doesn't compile seems a bit problematic to me.  I 
don't think a new user would be able to decipher what is going on and 
determine what they need to fix.

-Allen

Roman Yakovenko wrote:
> On Jan 15, 2008 1:02 AM, Allen Bierbaum <al...@vr...> wrote:
>> I am wrapping a method that looks something like this:
>>
>> class MyClass
>> {
>> public:
>>    void init(const unsigned value=0,
>>              const ClassB valueb=ClassB(-10.0, 11.0),
>>              const float other_val=2.0);
>> };
>>
>> When py++ wraps this it creates code like this:
>>
>> { //::MyClass::init
>>
>>              typedef void ( ::MyClass::*init_function_type )( ::unsigned
>> const,::ClassB const,::float const ) ;
>>
>>          MyClass_exposer.def( "init"
>>          , init_function_type( &::MyClass::init )
>>          , (  bp::arg("value")=(unsigned char const)(0)
>>          , bp::arg("valueb")=::ClassB( (&-1.0e+1), (&1.1e+1)
>>          , bp::arg("other_val")=2.0e+0 ) );
>> }
>>
>> As you can see the "&-1.0e+1" style values are invalid code and the
>> compiler fails to build the code.  Is this a know issue and is there a
>> simple work around or way to prevent py++ from generating code that
>> won't compile?
> 
> Yes, this is a known issue -
> http://language-binding.net/pygccxml/design.html#patchers
> 
> You have few ways to fix the problem:
> http://language-binding.net/pyplusplus/documentation/functions/default_args.html
> or
> mb = module_builder_t(...)
> mb.mem_fun( '::MyClass::init' ).arguments[1].default_value =
> 'ClassB(-10.0, 11.0)'
> 
> Choose the one you like
> 
> HTH
> 

Re: [pygccxml-development] py++ generating invalid default args code

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

On Jan 15, 2008 4:14 PM, Allen Bierbaum <al...@vr...> wrote:
> Is there a way to detect this problem is happening and output an error
> with a link to the documentation?  The way it works now where it
> generates code that doesn't compile seems a bit problematic to me.  I
> don't think a new user would be able to decipher what is going on and
> determine what they need to fix.

If I would now to detect such use case I would treat them in Py++.

For free and non virtual member functions you can use next functionality
http://language-binding.net/pyplusplus/documentation/functions/default_args.html

What user you mean by "a new user" - a bindings developer or final
user, who will run the script and compile generated code?

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