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148 lines
3.9 KiB
148 lines
3.9 KiB
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/*
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*
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*
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* _INVAR.H
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*
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* Purpose:
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* Template class designed to call parameterized object's Invariant().
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*
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* Overview (see also, usage):
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* 1) declare and define a public const function BOOL Invariant( void ) in your class, with #ifdef DEBUG.
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* 2) in the source: #define DEBUG_CLASSNAME to be the name of the class you're debugging.
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* 3) followed by #include "_invar.h"
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* 4) For every method you wish to check Invariants,
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* insert the _TEST_INVARIANT_ macro once, usually at the beginning of a routine.
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* OPTIONAL: You may optionally use the _TEST_INVARIANT_ON (x) to call x's Invariant directly.
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*
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* Notes:
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* Invariants are designed to be called at the beginning and upon exit of a routine,
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* testing the consistent properties of an object which remain invariant--always the same.
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*
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* Functions may temporarily make an object inconsistent during their execution.
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* A generalized invariant test should not be called during these inconsistent times;
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* if there is a need for a function, which checks invariants, to be called during
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* an inconsistent object state, a solution will need to be designed--the current design
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* does not facilitate this.
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*
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* Because it is entirely possible for an Invariant() function to recurse on itself
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* causing a stack overflow, the template explicitly prevents this from happening.
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* The template also prevents invariant-checking during the processing of Assert(),
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* preventing another type of recursion.
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*
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* Currently Invariant() returns a BOOL, as I think this allows for it to be called
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* from the QuickWatch window under VC++2.0. TRUE indicates that the invariant executed
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* normally.
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*
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* Usage:
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* -the _invariant.h header should only be included in source files. An error will occur
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* if included in another header file. This is to prevent multiple #define DEBUG_CLASSNAME.
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* -Typical #include into a source file looks like this:
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#define DEBUG_CLASSNAME ClassName
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#include "_invar.h"
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* -Typical definition of a class' Invariant() method looks like this:
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#ifdef DEBUG
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public:
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BOOL Invariant( void ) const;
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protected:
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#endif // DEBUG
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* -Typical declaration of Invariant() looks like this:
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#ifdef DEBUG
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BOOL
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ClassName::Invariant( void ) const
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{
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static LONG numTests = 0;
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numTests++; // how many times we've been called.
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// do mega-assert checking here.
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return TRUE;
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}
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#endif // DEBUG
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*
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*
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*
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*
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* Author:
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* Jon Matousek (jonmat) 5/04/1995
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*
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* Any problems? Please let me know.
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*/
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#ifndef _INVARIANT_H
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#define _INVARIANT_H
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#ifndef DEBUG_CLASSNAME
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prior to including _invariant.h file, you must define DEBUG_CLASSNAME
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to be the name of the class for which you are making Invariant() calls.
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#endif
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#ifdef DEBUG
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template < class T >
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class InvariantDebug
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{
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public:
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InvariantDebug ( const T & t) : _t(t)
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{
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static volatile BOOL fRecurse = FALSE;
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if ( fRecurse ) return; /* Don't allow recursion.*/
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fRecurse = TRUE;
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_t.Invariant();
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fRecurse = FALSE;
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}
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~InvariantDebug ()
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{
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static volatile BOOL fRecurse = FALSE;
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if ( fRecurse ) return; /* Don't allow recursion.*/
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fRecurse = TRUE;
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_t.Invariant();
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fRecurse = FALSE;
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}
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private:
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const T &_t;
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};
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typedef InvariantDebug<DEBUG_CLASSNAME> DoInvariant;
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#define _TEST_INVARIANT_ DoInvariant __invariant_tester( *this );
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#define _TEST_INVARIANT_ON(x) \
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{\
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static volatile BOOL fRecurse = FALSE;\
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if (FALSE == fRecurse )\
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{\
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fRecurse = TRUE;\
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(x).Invariant();\
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fRecurse = FALSE;\
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}\
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}
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#else // DEBUG
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#define _TEST_INVARIANT_
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#define _TEST_INVARIANT_ON(x)
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#endif // DEBUG
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// code that should be at the start and end of all Invariant() methods.
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#else // INVARIANT_H
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This file should only be included once per source file. jonmat
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#endif // INVARIANT_H
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