Re: [Swig-user] Typemaps returning wrapped replacement types

[James B. <bi...@cs...>]

John Pye wrote:
> Hi all
> 
> I've got some queries with the use of 'typemaps' in SWIG.
> 
> In my interface, lots of methods receive and output values of a
> *templated* C++ type called 'Units'. I don't want to make this class
> visible to the scripting language, so I want to typemap all Units
> arguments (ie Units<int m, int l, int t, int k, int i>, with all
> possible variations of m,l,t,k,i) to a single class called 'Measurement'
> which will be complete exposed to the scripting language through SWIG.
> 
> Most of the examples in the manual talk about converting to and from
> string, int, char etc. But in this case I want to return not a native
> script-language object (so PyInt_fromInt etc), but another SWIG-wrapped
> object. And can I do this in a language-neutral way?
> 
> What is the right way to do that? something like this?
> 
> %typemap(in) Units<1,0,-1>{
>     // convert a received Measurement object to Units<1,0,-1> for use in C++
>     $1 = Units<1,0,-1>($input);
> }
> %typemap(out) Units<1,0,-1>{
>     // convert an internal Units<1,0,-1> to a Measurement object for use
> in the scripting language
>     $result = Measurement($1);
> }

I'm not an expert, but have you tried to using typedef (typedef 
Units<1,0,-1> Units10M1;) to see if that has an effect?

> Also, is there any way I can do something like the following:
> 
> template<int m, int l, int t, int k, int i>
> %typemap(in) Units<m,l,t,k,i>{
>     $1 = MassFlowRate($input);
> }

I believe you can do this with a %define:

%define %Units_typemap(m,l,t,k,i)
%typemap(in) Units<m,l,t,k,i> {
     $1 = MassFlowRate($input);
}

%Units_typemap(1,0,-1,1,0);

James