🚀 go-pugleaf

fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON) writes:

>steve@taumet.com (Steve Clamage) writes:

>>mpk9172@ultb.isc.rit.edu (M.P. Kirby) writes:
>>
>>>In C I used to use a memory leak finder that would help me find
>>>my memory leaks.  I basically created a #define for malloc that redefined
>>>it ...

>>>I would like to do the same kind of thing in C++...

>>You do NOT want to replace "new" with a macro.  "new" is
>>a keyword which causes constructors to be called, and memory to be
>>allocated via the function "operator new()".  If you replace the "new"
>>keyword with a macro, you destroy the semantics of most programs.

>Unfortunately, we DO want to replace "new" with a macro, so that we can
>get __LINE__ and __FILE__. Redefining operator new() is not sufficient, because
>__LINE__ inside operator new() refers to the line where operator new() was
>redefined, not the line where new was invoked. ...

>The only way that I can see of solving the problem is to write a preprocessor
>which properly parses the source code, and then does the desired replacements.
>I don't see how it could be done using just the simple textual substitution
>provided by the C preprocessor.

If you don't mind modifying the source code, you can use placement syntax.
For example, instead of
        T* p = new T;
you would use
        T* p = new (__FILE__, __LINE__) T;
The result would be a call to
        operator new(size_t size, char* file, int line)
which would be your specialized allocation function.

You could use a macro to make this less tedious:
	#define my_new(x)	new (__FILE__, __LINE__) x
	...
	T* p = my_new(T);
 
Then write your own operator delete.  You have to be aware that there may
be calls to ordinary operator new from the library or other code.  Your
operator delete has to be able to cope with both, since there can be
only one (global) operator delete in the system.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com
Vice Chair, ANSI C++ Committee, X3J16