initialization of XXX_COOKIE in C source files

[Barry Smith]

>
> Now I am a little worried. Don't some compilers dislike  
> unintialized, file scope
> variables in shared libraries (I am thinking AIX).
>
>  Matt

     If the need arises I will put all the = 0 back in.

     We never got AIX shared libraries to work anyways :-)

    Barry

On May 11, 2008, at 7:07 AM, Matthew Knepley wrote:

> On Sat, May 10, 2008 at 7:49 PM, Barry Smith <bsmith at mcs.anl.gov>  
> wrote:
>>
>> On May 10, 2008, at 6:08 PM, Lisandro Dalcin wrote:
>>
>>
>>> I've noticed that in 2.3.3 all PETSc cookies are initialized to zero
>>> in sources, but in DEV they are not initialized. What's the reason  
>>> of
>>>
>>                                                 ^^^^^^^^^^^^^^^^
>>                                    You are quick, I just pushed the  
>> change
>> last night.
>>
>>    The reason why they where all initialized to zero was because
>> - a very long time ago all the cookies where hardwired numbers that  
>> we
>>   chose for each new class
>> - then we added the ability to request a cookie, but still support  
>> the old
>>  hardwired version. Passing in a pointer to a zero value meant you  
>> were
>>  requesting one, passing in a pointer to a nonzero one meant that the
>> cookie
>>  had a hardwired value.
>> - over time all the hardwired ones were unhardwired, but the  
>> convention
>>  of initializing them to zero before hand was never changed.
>>
>>  There was some convoluted logic for why the PetscEvent values were
>> all initialized to zero also. When fixing up the events I also  
>> fixed the
>> cookies
>> The reason is Barry's rule # 54, "nothing should be done in a code  
>> without
>> a reason, otherwise it will be confusing to others looking at the  
>> code."
>> For example,
>> even now, whenever anybody made some new events they initialized them
>> to zero, why? Not because they need to be, but simply because they  
>> were in
>> code the developer copied from.
>>
>>  Were you taking advantage of their initialization to zero? If so,  
>> rather
>> than depending
>> on each cookie being initialized to zero I would suggest handling  
>> this type
>> of "check if initialized" stuff at a package by package level or  
>> library by
>> library level.
>> Please let me know what you need.
>
> Now I am a little worried. Don't some compilers dislike  
> unintialized, file scope
> variables in shared libraries (I am thinking AIX).
>
>  Matt
>
>>  Barry
>>
>>
>>
>>
>>>
>>> this change?
>>>
>>> --
>>>
>>> Lisandro Dalcín
>>> ---------------
>>> Centro Internacional de Métodos Computacionales en Ingeniería  
>>> (CIMEC)
>>> Instituto de Desarrollo Tecnológico para la Industria Química  
>>> (INTEC)
>>> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
>>> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
>>> Tel/Fax: +54-(0)342-451.1594
>>>
>>>
>>
>>
>
>
>
> -- 
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which
> their experiments lead.
> -- Norbert Wiener
>