Re: How to Emulate C++ Macro with Static Local Variable?

[Jeffrey Carter <spam@spam.com>]

taashlo@sandia.gov wrote:

> tmoran@acm.org writes:
 >
>> void log(int *t){if(*t++ > 100)raise_the_exception;}
>> #define LOG if (1) { \
>>    static int t_; \
>>    log(&t_);\
>>  } else ((void)0)

Are ints in C++ automatically initialized to zero? I admit my C++ is not 
very good, but this looks as if it could raise the exception after fewer 
than 100 invokations, or after 101 invocations. (I assume this is C++ 
and not C because I don't recall C having exceptions.)

> There's only two options that I can think of:
> 
> 1) Use a unique ID for each call.  But this turns into a maintenance
> nightmare when you get a few hundred calls or more.
> 
> 2) Use the return address of the call.  But there was a short discussion
> about how Ada doesn't currently have a way of accessing the return
> address of a subprogram.

3. Use a unique instantiation of a generic package for each call. The 
instantiations of the package must be at a nesting level that ensures 
that they will exist for the entire lifetime of the executable region in 
which they are used.

-- 
Jeff Carter
"You tiny-brained wipers of other people's bottoms!"
Monty Python & the Holy Grail
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