[Cook] (ingredients-)fingerprint question.

[pdh]

In this case I'm just working with text files where the actual content 
and presence
of the input files are more important than timestamps... (it is not 
about building a
program)... timestamps are messed up by other tools beyond my control...

The recipe actually works, except for the second run ... and as far as I 
can tell,
that's because the ingredients-list is not fingerprinted on the first run.

Using only the ingredients-fingerprint feature, I still have strange 
results:

recipe:

summ : [glob "*.txt"]
    set ingredients-fingerprint
{
    cat [need] > [target];
}
then
{
    function print "Ingredients-list:" [need];
}

Starting with an empty directory with only this recipe present:

$ echo 1 > 1.txt
$ cook
/* .cookrc.list, /home/pdh/dev/buildtools/cook, Sun Nov 15 15:06 2009 */
cook: cat 1.txt > summ
cook: Ingredients-list: 1.txt
$
$ echo 2 > 2.txt
$ touch summ
$ cook
/* .cookrc.list, /home/pdh/dev/buildtools/cook, Sun Nov 15 15:06 2009 */
cook: Ingredients-list: 1.txt 2.txt
cook: the "summ" file is already up to date, no action required
$

 From the documentation I expected cook to rebuild the target (regardless
of its timestamp) because it's ingredients-list changed but that's not the
case.

So, it that correct behavior then?  I am not a programmer so this could
very well be desired behaviour for cook as a build tool for programs.
(If so, I need to solve my problem through other means).

Thanks


Aryeh M. Friedman wrote:
> Fingerprints are based on file content not on time stamp (i.e. I can 
> "touch" the file and cook will still see it as the same)... the only 
> way to fix this is to use time stamps not finger print on the 
> particular file (I don't have the manual handy so you will have to 
> look the syntex up)... but you really should be sure if this is what 
> you *REALLY* want because fingerprint using actual file contents is 
> 99.9999...% of the time correct (namely every time I think I have a 
> problem like this it turns out to be something else)
>
> dwark wrote:
>> Hi List,
>>
>> I am new to cook and I'm trying to create a recipe that will
>> create a summary out of a changing set of files.  The summary
>> should be rebuilt whenever a file is added/removed or updated
>> (i.e. contents changed).
>>
>> The combination of fingerprints and ingredients-fingerprint
>> looks to be a perfect match and indeed works largely as advertised.
>> Except for when the set of input files grows from 1 to 2 files,
>> for the first time.
>>
>> It looks like the ingredients-fingerprint is not taken when
>> the target is being built for the first time. The second
>> time around, cook can't see if the list has changed.
>>
>> Another thing is that fingerprinting the target itself, seems
>> to rejuvenate the target file to an age younger than it should
>> be (in the example below, summ should not be younger than 2.txt
>> during the second run).
>>
>> Am I missing something, like an additional flag or something? 
>> The current workaround is to force the recipe when there are only 2 
>> input files.
>>
>> Any hints/pointers would be appreciated.
>>
>> Thanks,
>>
>>