std::unique_ptr with custom deleter for win32 LocalFree

Question

I have the win32 API CommandLineToArgvW which returns a LPWSTR* and warns me that

CommandLineToArgvW allocates a

Answer 1

It looks correct to me. You could make it a little more succinct by specifying the unique_ptr's deleter inline rather than creating a functor for it.

std::unique_ptr 
      p( ::CommandLineToArgvW( L"cmd.exe p1 p2 p3", &n ), ::LocalFree );

Or, if you don't want to mess with LocalFree's signature and calling conventions you can use a lambda to do the deletion.

std::unique_ptr 
      p( ::CommandLineToArgvW( L"cmd.exe p1 p2 p3", &n ), 
         [](LPWSTR *ptr){ ::LocalFree( ptr ); } );

Note: At the time this answer was first written, VS2010 was the released VS version available. It doesn't support conversion of capture-less lambdas to function pointers, so you'd have to use std::function in the second example

std::unique_ptr> 
      p( ::CommandLineToArgvW( L"cmd.exe p1 p2 p3", &n ), 
         [](LPWSTR *ptr){ ::LocalFree( ptr ); } );