...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
BOOST_CONTRACT_CONSTRUCTOR — Program contracts that can be completely disabled at compile-time for constructors.
// In header: <boost/contract_macro.hpp>
BOOST_CONTRACT_CONSTRUCTOR(...)
This is used together with BOOST_CONTRACT_POSTCONDITION
, BOOST_CONTRACT_EXCEPT
, and BOOST_CONTRACT_OLD
to specify postconditions, exception guarantees, and old value copies at body that can be completely disabled at compile-time for constructors (see BOOST_CONTRACT_CONSTRUCTOR_PRECONDITION
to specify preconditions for constructors):
class u { friend class boost::contract::access; BOOST_CONTRACT_INVARIANT({ // Optional (as for static and volatile). BOOST_CONTRACT_ASSERT(...); ... }) public: u(...) { BOOST_CONTRACT_OLD_PTR(old_type)(old_var); BOOST_CONTRACT_CONSTRUCTOR(this) // No `PRECONDITION` (use `CONSTRUCTOR_PRECONDITION` if needed). BOOST_CONTRACT_OLD([&] { // Optional. old_var = BOOST_CONTRACT_OLDOF(old_epxr); ... }) BOOST_CONTRACT_POSTCONDITION([&] { // Optional. BOOST_CONTRACT_ASSERT(...); ... }) BOOST_CONTRACT_EXCEPT([&] { // Optional. BOOST_CONTRACT_ASSERT(...); ... }) ; ... // Constructor body. } ... };
For optimization, this can be omitted for constructors that do not have postconditions and exception guarantees, within classes that have no invariants.
BOOST_CONTRACT_CONSTRUCTOR(obj)
expands to code equivalent to the following (note that no code is generated when BOOST_CONTRACT_NO_CONSTRUCTORS
is defined):
#ifndef BOOST_CONTRACT_NO_CONSTRUCTORS boost::contract::check internal_var = boost::contract::constructor(obj) #endif
Where:
obj
is the object this
from the scope of the enclosing constructor declaring the contract. Constructors check all class invariants, including static and volatile invariants (see BOOST_CONTRACT_INVARIANT
, BOOST_CONTRACT_STATIC_INVARIANT
, and BOOST_CONTRACT_INVARIANT_VOLATILE
). (This is a variadic macro parameter so it can contain commas not protected by round parenthesis.)
internal_var
is a variable name internally generated by this library (this name is unique but only on different line numbers so this macro cannot be expanded multiple times on the same line).
See Also:
Disable Contract Compilation, Constructors