Method set

tests/catch.h:4090–4095

        struct BoundNullaryMethod : IArgFunction<C>{
            BoundNullaryMethod( void (C::*_member)() ) : member( _member ) {}
            virtual void set( C& p, std::string const& stringValue ) const {
                bool value;
                convertInto( stringValue, value );
                if( value )
                    (p.*member)();
            }
            virtual void setFlag( C& p ) const {
                (p.*member)();
            }