Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the develop branch, built from commit c5994560ca.
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Macro BOOST_CONTRACT_OLDOF

BOOST_CONTRACT_OLDOF — Macro typically used to copy an old value expression and assign it to an old value pointer.

Synopsis

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

BOOST_CONTRACT_OLDOF(...)

Description

The expression expanded by this macro should be assigned to an old value pointer of type boost::contract::old_ptr or boost::contract::old_ptr_if_copyable. This is an overloaded variadic macro and it can be used in the following different ways.

1. From within virtual public functions and public functions overrides:

BOOST_CONTRACT_OLDOF(v, old_expr)

2. From all other operations:

BOOST_CONTRACT_OLDOF(old_expr)

Where:

  • v is the extra parameter of type boost::contract::virtual_* and default value 0 from the enclosing virtual public function or public function overrides declaring the contract.

  • old_expr is the expression to be evaluated and copied into the old value pointer. (This is not a variadic macro parameter so any comma it might contain must be protected by round parenthesis and BOOST_CONTRACT_OLDOF(v, (old_expr)) will always work.)

On compilers that do not support variadic macros, programmers can manually copy old value expressions without using this macro (see No Macros).

See Also:

Old Values


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