CODEWITHSUNDEEP
c++c++20
Bertwim van Beest
Bertwim van Beest

Reputation: 1791

How to bind std::filesystem::copy?

I would like to bind the third argument of the std::filesystem::copy, i.e.

void copy( const std::filesystem::path& from,
           const std::filesystem::path& to,
           std::filesystem::copy_options options );

to a certain value, say std::filesystem::copy_options::none.

When I do:

namespace fs = std::filesystem;
auto f1 = std::bind( fs::copy, _1, _2, fs::copy_options::none );

the gcc compiler (10.3.0, c++20) gives an error (see below): What am I doing wrong? Bertwim

> error: no matching function for call to ‘bind(<unresolved overloaded
> function type>, const std::_Placeholder<1>&, const
> std::_Placeholder<2>&, std::filesystem::copy_options)’   641 |        
> auto f2 = std::bind( fs::copy, std::placeholders::_1,
> std::placeholders::_2, fs::copy_options::none );

Upvotes: 1

Views: 122

Answers (1)

NathanOliver
NathanOliver

Reputation: 180510

std::filesystem::copy is an overloaded function. That means that it's name cannot decay into a single type since we don't know which overload you want. You could fix that with a cast but instead of doing that you can use a lambda expression to create your wrapper like

auto f1 = [](const auto& from, const auto& to) {
              fs::copy(from, to, fs::copy_options::none); 
          };

Upvotes: 4

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