ENH: Equivalent to subprocess.check_output

[Wes Turner]

Is there a (easy) way to raise an Exception if the returncode is not (by default?) 0?

[Wes Turner]

e.g. expect_returncode=0 or expect_returncode=2

[Wes Turner]

... looking for a way to avoid having to add

  if p.returncode != 0:
    raise subprocess.CalledProcessError()

when porting from subprocess.

[Wes Turner]

https://docs.python.org/2/library/subprocess.html#subprocess.check_output

[Vinay Sajip]

This seems a reasonable request, I will look at implementing it soon.

[Wes Turner]

So, here's this, which adds an expect_returncode kwarg: https://bitbucket.org/westurner/sarge/commits/6cc7780f00ccba2a231c2b7c51cb2a29d287e660

It may be a bit overzealous; there's probably a better way to accomplish this.

check_output and check_call could then just be partials of run.

[Wes Turner]

From discussions here: https://mail.python.org/pipermail/python-ideas/2015-January/031479.html ... https://mail.python.org/pipermail/python-ideas/2015-February/031532.html

It's been suggested that check would be sufficient, but TBH expect_returncode seems preferable because it should be relatively grep'able.

[Wes Turner]

Maybe assert_returncode would be more palatable?

[Wes Turner]

assert_returncode feels too much like a test, which this isn't; or an assertion that could be compiled out with -O 2, so, sticking with expect_returncode

check_returncode doesn't seem to have the same implications as expect_.

Pending further input, I'll stick with expect_returncode.

[Vinay Sajip]

Might there be use cases where several return codes might be OK? In which case, expected_returncodes could be passed as None or a tuple of integers (and perhaps a single integer which would be treated the same as a singleton tuple).

[Wes Turner]

https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-check_call-check_output/diff

Might there be use cases where several return codes might be OK? In which case, expected_returncodes could be passed as None or a tuple of integers (and perhaps a single integer which would be treated the same as a singleton tuple).

Is this needed just for Pipeline.run?

[Wes Turner]

I've added support for expect_returncode as a tuple or a list in "ENH: Support Pipeline.run expect_returncode=(int || tuple || list)"

PR here: https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-check_call-check_output

[pahaz NA]

expect_returncode - not a unix way. In all normal cases this argument must be set to 0. I think that this argument would be superfluous. He degrades the readability and understandability of code.

[Wes Turner]

No check is performed when expect_returncode is None (the default).

The alternative is to copy and paste this each time: https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-call-check_call-check_output/diff#Lsarge/init.pyT1062

[edit] https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-call-check_call-check_output/diff#Lsarge/init.pyT1062

[edit] fenced code block of markdown (```markdown\n...\n```) for the above:

https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-call-check_call-check_output/diff#Lsarge/__init__.pyT1062

[https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-call-check_call-check_output/diff#Lsarge/__init__.pyT1062](https://bitbucket.org/vinay.sajip/sarge/pull-request/1/enh-add-call-check_call-check_output/diff#Lsarge/__init__.pyT1062)

[Wes Turner]

Looks like bitbucket markdown link heuristics are off. This is the linked code block:

            if isinstance(expect_returncode, (tuple, list)):
                if list(self.returncodes) != list(expect_returncode):
                    raise CalledProcessError(
                        self.returncode,
                        self,
                        expected_returncode=expect_returncode)
            else:
                if self.returncode != expect_returncode:
                    raise CalledProcessError(
                        self.returncode,
                        self,
                        expected_returncode=expect_returncode)