libsigc++ ships with basic lambda functionality and the sigc::group adaptor, which uses lambdas to transform a functor's parameter list. More...

Modules
	group()
	sigc::group() alters an arbitrary functor by rebuilding its arguments from one or more lambda expressions.

Classes
struct	sigc::lambda_base
	A hint to the compiler. More...
struct	sigc::lambda< T_type >
	Lambda type. More...

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Detailed Description

libsigc++ ships with basic lambda functionality and the sigc::group adaptor, which uses lambdas to transform a functor's parameter list.

The lambda selectors sigc::_1, sigc::_2, ..., sigc::_9 are used to select the first, second, ..., nineth argument from a list.

Examples:

 std::cout << sigc::_1(10,20,30); // returns 10
 std::cout << sigc::_2(10,20,30); // returns 20

Operators are defined so that, for example, lambda selectors can be used as placeholders in arithmetic expressions.

Examples:

 std::cout << (sigc::_1 + 5)(3); // returns (3 + 5)
 std::cout << (sigc::_1 * sigc::_2)(7,10); // returns (7 * 10)

If your compiler supports C++11 lambda expressions, they are often a good alternative to libsigc++'s lambda expressions. The following examples are equivalent to the previous ones.

 [] (int x, int, int) -> int { return x; }(10,20,30); // returns 10
 [] (int, int y, int) -> int { return y; }(10,20,30); // returns 20
 [] (int x) -> int { return x + 5; }(3); // returns (3 + 5)
 [] (int x, int y) -> int { return x * y; }(7,10); // returns (7 * 10)