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From: Roman Y. <rom...@gm...> - 2009-11-15 19:15:29
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On Sun, Nov 15, 2009 at 6:22 PM, Gustavo Carneiro <gjc...@gm...> wrote:
> Hi, I have a problem here that I do not know where to begin to solve. I use
> pygccxml.declarations.templates.split(), but it returns a list of template
> parameters as strings, while I need to declarations of the classes listed as
> template arguments (long story, but I really do).
Been there, done it :-)
> Is there a simple API in
> pygccxml that would allow me to go from a string like
> "ns3::dot11s::IeBeaconTimingUnit" to the actual declaration of the class?
> Or any other method rather than templates.split() that would give me the
> template args already as declarations?
May be, lets see.
In general I found 2 different ways to solve this problem.
The first one is deterministic - if you have template instantiated
class in your hands and it has typedef for its template parameters,
then you can use this fact:
template< class T>
struct Wrapper{
typedef T value_type;
...
};
pygccxml provides "internal_type_traits.get_by_name" method to get
reference to "type_t"
The second way: start parsing and searching :-).
I suggest you to take a look on container_traits.py module. It tries
to extract [value|element] type from std::[container]. It treats 2 use
cases:
* the input is class definition - so using typedef's defined in the
container class, it finds the actual template parameter type
* the input is class declaration ( in case in code was written forward
declaration ) - in this case the parsing of arguments is done and then
global namespace is searched. Take a look on
type_traits.impl_details.find_value_type method.
The second way works most of the time, when it doesn't you have few choices:
* create dummy type (dummy_type_t), which will return parameter string
as-is. In some of my cases, I use meta-programming to select the
desired functionality
* raise an exception and ask user to specify the type explicitly -
good error message will solve you headache and simplify a few things
for the user :-)
HTH
--
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/
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