...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_PUBLIC_FUNCTION — Program contracts that can be completely disabled at compile-time for non-static public functions that do not override.
// In header: <boost/contract_macro.hpp>
BOOST_CONTRACT_PUBLIC_FUNCTION(...)
This is used together with BOOST_CONTRACT_PRECONDITION
, BOOST_CONTRACT_POSTCONDITION
, BOOST_CONTRACT_EXCEPT
, and BOOST_CONTRACT_OLD
to specify preconditions, postconditions, exception guarantees, and old value copies at body that can be completely disabled at compile-time for non-static public functions (virtual or not, void or not) that do not override:
class u { friend class boost::contract::access; BOOST_CONTRACT_INVARIANT({ // Optional (as for static and volatile). BOOST_CONTRACT_ASSERT(...); ... }) public: // Non-virtual (same if void). t f(...) { t result; BOOST_CONTRACT_OLD_PTR(old_type)(old_var); BOOST_CONTRACT_PUBLIC_FUNCTION(this) BOOST_CONTRACT_PRECONDITION([&] { // Optional. BOOST_CONTRACT_ASSERT(...); ... }) BOOST_CONTRACT_OLD([&] { // Optional. old_var = BOOST_CONTRACT_OLDOF(old_expr); ... }) BOOST_CONTRACT_POSTCONDITION([&] { // Optional. BOOST_CONTRACT_ASSERT(...); ... }) BOOST_CONTRACT_EXCEPT([&] { // Optional. BOOST_CONTRACT_ASSERT(...); ... }) ; ... // Function body (use `return result = return_expr`). } // Virtual and void. virtual void g(..., boost::contract::virtual_* v = 0) { BOOST_CONTRACT_OLD_PTR(old_type)(old_var); BOOST_CONTRACT_PUBLIC_FUNCTION(v, this) ... BOOST_CONTRACT_OLD([&] { // Optional. old_var = BOOST_CONTRACT_OLDOF(v, old_expr); ... }) ... ; ... // Function body. } // Virtual and non-void. virtual t h(..., boost::contract::virtual_* v = 0) { t result; BOOST_CONTRACT_OLD_PTR(old_type)(old_var); BOOST_CONTRACT_PUBLIC_FUNCTION(v, result, this) ... BOOST_CONTRACT_OLD([&] { // Optional. old_var = BOOST_CONTRACT_OLDOF(v, old_expr); ... }) BOOST_CONTRACT_POSTCONDITION([&] (t const& result) { // Optional BOOST_CONTRACT_ASSERT(...); ... }) ... ; ... // Function body (use `return result = return_expr`). } ... };
For optimization, this can be omitted for non-virtual public functions that do not have preconditions, postconditions and exception guarantees, within classes that have no invariants. Virtual public functions should always use BOOST_CONTRACT_PUBLIC_FUNCTION
otherwise this library will not be able to correctly use them for subcontracting.
This is an overloaded variadic macro and it can be used in the following different ways (note that no code is generated when BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS
is defined).
1. BOOST_CONTRACT_PUBLIC_FUNCTION(obj)
expands to code equivalent to the following (for non-virtual public functions that are not static and do not override, returning void or not):
#ifndef BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS boost::contract::check internal_var = boost::contract::public_function(obj) #endif
2. BOOST_CONTRACT_PUBLIC_FUNCTION(v, obj)
expands to code equivalent to the following (for virtual public functions that are not static and do not override, returning void):
#ifndef BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS boost::contract::check internal_var = boost::contract::public_function(v, obj) #endif
3. BOOST_CONTRACT_PUBLIC_FUNCTION(v, r, obj)
expands to code equivalent to the following (for virtual public functions that are not static and do not override, not returning void):
#ifndef BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS boost::contract::check internal_var = boost::contract::public_function(v, r, obj) #endif
Where (these are all variadic macro parameters so they can contain commas not protected by round parenthesis):
v
is the extra parameter of type boost::contract::virtual_
*
and default value 0
from the enclosing virtual public function declaring the contract.
r
is a reference to the return value of the enclosing virtual public function declaring the contract. This is usually a local variable declared by the enclosing virtual public function just before the contract, but programmers must set it to the actual value being returned by the function at each return
statement.
obj
is the object this
from the scope of the enclosing public function declaring the contract. This object might be mutable, const
, volatile
, or const volatile
depending on the cv-qualifier of the enclosing function (volatile public functions will check volatile class invariants, see
Volatile Public Functions).
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, Public Functions, Virtual Public Functions