Re: Using hash instead of timestamps to check for changes.

[Yukimasa Sugizaki]

Hi.

Notice that I am not a GNU Make developer.

The feature which checks updates depend on file content differ of each file is 
not implemented on GNU Make currently.
(I think it won't be implemented because timestamp-based update checking is 
normal behavior of Make.)

If you want to check updates by such way,
you can do this by using GNU Make macros like this:


all: prog

$(shell test -f src.c.prev && (diff -q src.c.prev src.c || touch src.c.flg) || 
touch src.c.flg)

prog: src.c.flg
    $(CC) src.c $(OUTPUT_OPTION)


Regards.

2015/03/27 22:42、Glen Stark <address@hidden> のメッセージ:

> Greetings.
> 
> I hope that this is the correct forum for this question.  As a quick
> search on Google will verify, there's quite a bit of interest in being
> able to have Make use a hash to check if a new build is required, as
> opposed to a timestamp.
> 
> I searched the mailing lists regarding this issue, and found a rather
> old patch suggestion, but have not been able to determine if a decision
> was made regarding whether to implement this feature.  Nor have I been
> able to find relevant information on the Make project website, so I'm
> asking you Make maintainers if you see this as a desirable
> functionality, or at least worthy of discussion.  I can say that it
> would benefit my colleagues and I enormously, and I'm willing to attempt
> the implementation if you agree it would be a feature worth adding.
> 
> So to start with: 
> 
> Is this planned?  Has the idea already been rejected, and if so could
> you point me to the discussion so I can inform myself?
> 
> If it is planned, or you agree it's worth doing, how can I help?  I'm
> willing to write the code if someone is willing to help me work into the
> code a little.  Until now I'm only a user, not maintainer of Make, and
> would need some tips about how to fit the functionality into the overall
> design of Make.  Someone to bounce ideas off, and direct questions to
> would be wonderful.  If someone else is working on it already, I'd like
> to help however I can -- testing, debugging, etc.
> 
> Thank you for your time.
> 
> Glen Stark
> 
> 
> 
> 
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