CODEWITHSUNDEEP
c++lambdac++11
Shai Deshe
Shai Deshe

Reputation: 153

no match for call when using c++0x Lambda expressions

This is the problematic function:

void Molecule::initSimilarity(int depth)
{
    int m = 1;
    for (int j = 0; j < depth ; j++)
        for (int i = 0 ; i < _size ; i++)   //for any atom A
            if (!getSetMask(                //put all atoms which are equivalnt but not similar to A in their own
                                            //equivalence class
                [&](const Atom& b)->bool {return (_atoms[i]->_class == b._class) && !(isSimilar(*_atoms[i],b));},
                [&m](Atom& b){b._class = m;}     //113
                ).none()) m++;                   //114
}

And the output:

In file included from /usr/include/c++/4.5/memory:82:0,

             from /usr/include/boost/dynamic_bitset_fwd.hpp:15,
             from /usr/include/boost/dynamic_bitset/dynamic_bitset.hpp:36,
             from /usr/include/boost/dynamic_bitset.hpp:15,
             from DataStructures/Molecule.h:21,
             from DataStructures/Molecule.cpp:8:

/usr/include/c++/4.5/functional: In static member function ‘static void std::_Function_handler::_M_invoke(const std::_Any_data&, _ArgTypes ...) [with _Functor = Molecule::initSimilarity(int)::, _ArgTypes = {Atom}]’:

/usr/include/c++/4.5/functional:2103:6: instantiated from ‘std::function<_Res(_ArgTypes ...)>::function(_Functor, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type) [with _Functor = Molecule::initSimilarity(int)::, _Res = void, _ArgTypes = {Atom}, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type = std::function::_Useless]’

DataStructures/Molecule.cpp:114:5:
instantiated from here

/usr/include/c++/4.5/functional:1713:9: error: no match for call to

‘(Molecule::initSimilarity(int)::) (Atom)’

DataStructures/Molecule.cpp:113:17: note: candidate is: Molecule::initSimilarity(int)::

I have no idea how this happens and what exactly that means, and I couldn't find any help on Google either...

The called function (isSimilar()):

bool Molecule::isSimilar(const Atom &A, const Atom &B)
    {
        AtomSet S;
        for (int i = 0; i < _size; i++)
        {
            if (!_adjecancy[A._index][i]) continue; //Skip any atoms which aren't adjecant to A
            int K = findAtom([&](const Atom& b){return (_adjecancy[B._index][b._index]) && (B._class == b._class) && (!S[B._index]);});
            if (K == -1) return false;
            S.flip(K);
        }
        return true;
    }

and the one called from it:

int Molecule::findAtom(std::function<bool (const Atom)> property, std::function<void (Atom)> action = NULL)
{
    for (int i=0 ; i<_size ; i++)
    {
        if (property(*_atoms[i]))
        {
            if (action != NULL) action(*_atoms[i]);
            return i;
        }
    }
    return -1;
}

used typedefs:

typedef dynamic_bitset<> AtomSet;
typedef dynamic_bitset<>::size_type atom_ind;

and of course, the function which stars in the error output:

AtomSet Molecule::getSetMask(std::function<bool (const Atom)> property, std::function<void (Atom)> action = NULL)
{
    dynamic_bitset<> ret(_size);
    if (property != NULL) for(int i=0; i<_size ; i++) ret.set(i, property(*_atoms[i]));
    return ret;
}

Upvotes: 2

Views: 2962

Answers (1)

Ben Voigt
Ben Voigt

Reputation: 283921

I see references in the argument type of the lambda, and no references in the functor types needed by getSetMask.

Does your error persist if you make those consistent?

i.e. if you want action to modify the Atom, you need

std::function<void (Atom&)> action

Upvotes: 1

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