rubber always returns true

[Michael Schnupp]

Binary package hint: rubber

rubber should return a different exit value, depending on whether it had to modify the output file.

After printing a "nothing to be done for $target" it should return false, allowing for example shell scripts or make files to easily decide if further action is required.

[Emmanuel Beffara (manu-beffara)]

Hi,

Currently, rubber returns false if some processing failed, and true if everything went fine. This is standard behaviour: not doing anything because the output document is up to date is not a failure. I do think it is the way it should be.

I admit that it might be useful in some situations to detect if some processing was actually performed. However, I don't know of a standard way for a command to return such information. It would be easy to add a command-line switch so that false is returned when nothing was done, but then how could one distinguish that from an actual failure?

Emmanuel

[Michael Schnupp (michas)]

Maybe "nothing to be done" could be interpreted as a special kind of error. (i.e. another return value)
Like "yes, I build a new document as you changed the source" and "no, I didn't build it, as there is nothing to do" and "no, I couldn't build it as there was some kind of error.".

But for me it was more a whishlist item, as it seemed as the return value is actually not used and simply always returns true.

[Alex Hirzel (alhirzel)]

gmake has a -q/--question flag that will determine if a rebuild is necessary but not perform it. pmake does not have a similar behavior. I propose we adopt the --question flag with the following behavior:

If any output files would be rebuilt return 1, else return 0.

This covers all use cases that come to my mind. It also avoids overloading the return value heavily.

[Sebastian Kapfer (caci)]

A --query flag sounds like a good solution. Patches welcome!