Sol2: problem with overload constant member functions

[spin-scenario]

I have two constant member functions in my 'spin_system' class.
SpMat op(const string& list, op_side type = kComm) const ;
SpMat op(const sol::table& t, op_side type = kComm) const ;

I found that the functions can't be resolved as follows:
lua.new_usertype<spin_system>("spin_system", sol::constructors<sol::types<string>, sol::types<sol::table>>(), "op", sol::overload( sol::resolve<SpMat(const string&, op_side)>(&spin_system::op), sol::resolve<SpMat(const sol::table&, op_side)>(&spin_system::op)) );

BUT! If the functions defined without 'const ', it works well. So how can we fix it? thanks.

[spin-scenario]

Also, there is another problem with my member functions. Note that the second parameter has a default value 'kComm', but in the lua script we have to always assign all the two parameters explicitly.

local Iz1=sys1:op("1, I-",0)
local Iz2=sys1:op({"1","I-"},0)

Any one can help me? Thanks a lot.

[ThePhD]

You cannot bind "default parameters". They exist solely at compile-time in C++ and the only way to mimic that would be to use deliberate overloading with sol::overload, that is you'd have to add 2 more overloads using a lambda or something to the list you have that take 1 argument and pass it to the C++ function.

The first problem seems like a bug on my end, but I'm not able to figure out a way around the template shenanigans required to capture this.

Therefore, I recommend that you use a static_cast<SpMat (spin_system::* )(const std::string&, op_side)const>( &spin_system::op );

[ThePhD]

Derp. I'm a dumby. All you need to solve this problem is:

sol::resolve<SpMat(const std::string&, op_side) const>( &spin_system::op );

Note the const at the end just before the close of the sol::resolve<...> template bit. You have to specify that to make it work. I'm going to add a note and example to the docs so future people (and myself) don't get all tripped up on this.

Thanks for reporting!

[ThePhD]

Fixed. http://sol2.readthedocs.io/en/latest/api/resolve.html

Pull from the latest to get what you need or grab the single: https://github.com/ThePhD/sol2/blob/develop/single/sol/sol.hpp

[spin-scenario]

Thank you very much for the perfect solution. The Sol2 is awsome.