class post_mem_fun A post condition class. More... Full name dbg::post_mem_fun Definition #include <dbg.h> Template form post_mem_fun<class obj_t> List of all Methods

Annotated List Files Globals Hierarchy Index

Public Methods

•  post_mem_fun (level lvl, obj_t *obj, fn_t fn, const source_pos &pos)
•  post_mem_fun (level lvl, dbg_source src, obj_t *obj, fn_t fn, const source_pos &pos)
•  post_mem_fun (obj_t *obj, fn_t fn, const source_pos &pos)
•  post_mem_fun (dbg_source src, obj_t *obj, fn_t fn, const source_pos &pos)
•  ~post_mem_fun ()
•  post_mem_fun (level, void *, fn_t, void *)
•  post_mem_fun (level, dbg_source, void *, fn_t, void *)
•  post_mem_fun (void *, fn_t, void *)
•  post_mem_fun (dbg_source, void *, fn_t, void *)
•  ~post_mem_fun ()

Detailed Description

A post condition class. This utility automates the checking of post conditions using assertion. It requires a member function with the signature:

     bool some_class::invariant() const;

When you create a post_mem_fun object you specify a post condition member function. When the post_mem_fun object is destroyed the postcondition is asserted.

This is useful for methods where there are a number of exit points which would make it tedious to put the same dbg::assertion in multiple places.

It is also handy when an exception might be thrown and propagated by a function, ensuring that a postcondition is first checked. Bear in mind that Bad Things can happen if the assertion_behaviour is assertions_throw and this is triggered via a propagating exception.

An example of usage, the do_test method below uses the post_mem_fun object:

     class test
     {
         public:
             test() : a(10) {}
             do_test()
             {
                 dbg::post_mem_fun
                    post(dbg::info, this, &test::invariant, DBG_HERE);
                 a = 9;
                 if (SOME_CONDITION)
                 {
                     return;                                      // (*)
                 }
                 else if (SOME_OTHER_CONDITION)
                 {
                     throw std::exception();                      // (*)
                 }
                                                                  // (*)
             }
         private:
             bool invariant()
             {
                 return a == 10;
             }
             int a;
     };

The post condition will be asserted at each point marked (*).

See also: post

Parameters:

lvl	Diagnostic level
obj	Object to invoke fn on (usually "this")
fn	Post condition member function
here	Supply DBG_HERE

Parameters:

lvl	Diagnostic level
src	String describing the diagnostic source
obj	Object to invoke fn on (usually "this")
fn	Post condition member function
here	Supply DBG_HERE

Overloaded version of constructor which defaults to the warning diagnostic level.

Parameters:

obj	Object to invoke fn on (usually "this")
fn	Post condition member function
here	Supply DBG_HERE

Overloaded version of constructor which defaults to the warning diagnostic level.

Parameters:

src	String describing the diagnostic source
obj	Object to invoke fn on (usually "this")
fn	Post condition member function
here	Supply DBG_HERE

The destructor asserts the post condition.