Re: Enhancement request: Watch source files for changes

[Philip Guenther]

On Wed, Feb 4, 2009 at 8:25 AM, Noah Slater <address@hidden> wrote:
> On Wed, Feb 04, 2009 at 03:59:45PM +0000, Tim Murphy wrote:
>> I am not an expert on the source code but I think it is a fairly large
>> change to try to apply to make.
>
> This would surprise me. Once the makefiles have been parsed and DAG has been
> built, GNU Make does a check of the filesystem. How hard could it be to put
> this last step in some kind of loop?

Putting the loop there would be incorrect, as then the dependency
graph wouldn't be updated when stuff changes in the filesystem.

(Caveat: I'm not a GNU make developer)

What seemed lacking to me in your original email was an analysis of
gains and losses of putting this functionality in to make.

- Why is this better built in than in a shell script wrapper (which
you already have!)?

- What problems with the shell script version are unsolvable there but solvable
  when built in?

- The shell script can be customized in a number of ways by simply
editing it.  Examples:
  o) changing the delay
  o) making the delay vary depending on whether anything was rebuilt
  o) triggering extra actions depending on whether anything was rebuilt
  o) filtering of output
  What's the plan for performing these customizations if this is built in?

- Is there precedent to this sort of enhancement, other build or
dependency tools
  that have done this sort of thing that could serve as a model?  If
this is completely
  a new area of design, then I would expect it to take several tries to get the
  behavior matching the user expectation

Those are just the sort of items I would consider if this was my
project; Paul and the other developers may have completely different
criteria in mind, but I would be surprised if they didn't overlap
some.


Philip Guenther