I would like to have a default functor for the functor parameter in the class constructor. As a minimal example, I came up with a class that should be a server as a filter that filters elements of type Tiif the filter function returns true. The filter function must be specified in the constructor, the default is to accept all:
template<class T>
class Filter
{
public:
typedef std::function<bool(const T&)> FilterFunc;
Filter(const FilterFunc & f = [](const T&){ return true; }) :
f(f)
{
}
private:
FilterFunc f;
};
I create an instance of the template class as follows:
int main() {
Filter<int> someInstance;
}
However, gcc 4.7 does not look like this piece of code :
prog.cpp: In constructor ‘Filter<T>::Filter(const FilterFunc&) [with T = int; Filter<T>::FilterFunc = std::function<bool(const int&)>]’:
prog.cpp:19:17: internal compiler error: in tsubst_copy, at cp/pt.c:12141
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
Preprocessed source stored into /home/g9i3n9/cc82xcqE.out file, please attach this to your bugreport.
What happened? Is my standard a standard code (so does GCC really buggy here or didn't implement this), or am I doing something wrong?
std::function (, ), :
Filter(const FilterFunc & f = FilterFunc) :
f(f)
{
}
void process() {
if (!f || f(someItem)) {
}
}