Function template condition_if_c

boost::contract::condition_if_c — Select compilation and execution of a boolean functor template condition using a static boolean predicate (not needed on C++17 compilers, use if constexpr instead).

Synopsis

// In header: <boost/contract/call_if.hpp>


template<bool Pred, typename Then> 
  bool condition_if_c(Then f, bool else_ = true);

Description

Compile and execute the nullary boolean functor template call f() if and only if the specified static boolean predicate Pred is true, otherwise trivially return else_ (true by default) at run-time.

A call to boost::contract::condition_if_c<Pred>(f, else_) is logically equivalent to boost::contract::call_if_c<Pred>(f, [] { return else_; }) (but its internal implementation is optimized and it does not actually use call_if_c).

See Also:

Assertion Requirements

Parameters:

`else_`	Boolean value to return when `Pred` is `false` (instead of compiling and executing the functor template call `f()`).
`f`	Nullary boolean functor template. The functor template call `f()` is compiled and executed if and only if `Pred` is `true`.

Template Parameters:

Pred

Static boolean predicate selecting when the functor template call f() should be compiled and executed.

Returns:

Boolean value returned by f() if the static predicate Pred is true. Otherwise, trivially return else_.

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