Reputation: 4002
I am trying to wrap a std::map using SWIG to python, and it works nicely, except that it leaks memory (my code below).
Apparently SWIG automatically frees the returned object's (the Tuple
) memory , but does not free the String
allocated inside it. I read that I can use explicit deallocation using %typemap(newfree)
, but no idea how to implement.
%typemap(out) std::pair<std::string, double> {
$result = PyTuple_Pack(2, PyUnicode_FromString($1.first.c_str()),
PyFloat_FromDouble($1.second));
};
%typemap(newfree) std::pair<std::string, double> {
// What to do here?
// delete[] $1.first.c_str() clearly not the way to go...
}
Upvotes: 1
Views: 440
Reputation: 177674
SWIG has pre-defined typemaps for pair
and string
, so you won't need to write them yourself:
test.i
%module test
// Add appropriate includes to wrapper
%{
#include <utility>
#include <string>
%}
// Use SWIG's pre-defined templates for pair and string
%include <std_pair.i>
%include <std_string.i>
// Instantiate code for your specific template.
%template(sdPair) std::pair<std::string,double>;
// Declare and wrap a function for demonstration.
%inline %{
std::pair<std::string,double> get()
{
return std::pair<std::string,double>("abcdefg",1.5);
}
%}
Demo:
>>> import test
>>> p = test.sdPair('abc',3.5)
>>> p.first
'abc'
>>> p.second
3.5
>>> test.get()
('abcdefg', 1.5)
Upvotes: 2