Execution context (default arguments) for custom command?

[jerkstorecaller]

I want sh to output to always output stdout/stderr as if I'd run the commands in a bash script, for every single command. Using the doc at https://amoffat.github.io/sh/sections/default_arguments.html as guide, I created a new sh2 object with my default argument for _out. However, it doesn't work for custom Commands, only for built-in commands.

import sh
import sys

sh2 = sh(_out=sys.stdout, _err=sys.stderr)

#correctly prints the output of "ls /etc" to stdout
sh2.ls("/etc")

subgit = sh2.Command("tools/subgit-3.3.11/bin/subgit")
#prints nothing
subgit("--version")
#prints the version correctly
subgit("--version", _out=sys.stdout)

It's not specific to this tool, it's the same result if I use myls = sh2.Command("/usr/bin/ls") .

[amoffat]

Huh, I think you have found a bug, and I think it is reasonable to expect that Command instances should inherit the default arguments from sh2. Thanks for reporting

[ecederstrand]

I can't reproduce this on my own machine.

@amoffat The beginning of SelfWrapper.__call__ looks very innocent. You've added a warning about some fragile code in

sh/sh.py

Line 3527 in b6cb96e

# inspect the line in the parent frame that calls and assigns the new sh

and forward. I assume this is where things are going wrong. Do you have any ideas how to improve?

[amoffat]

@ecederstrand here is what I am using to reproduce:

import sh

sh2 = sh(_ok_code=1)

sh2.ls() # raises
ls = sh2.Command("ls")
ls() # doesn't raise

It seems that the arguments that should be "baked" into sh2 aren't propagating to instances of the Command class

[ecederstrand]

I created a minimal PR for this. The caveat is that sh.Command("ls") now also gets the _ok_code=1 call arg. That's one step forward and one step back, IMHO. I can't see how to fix that without also creating wrapper code for Command. Any ides?

[ecederstrand]

I've updated the PR without the above caveat and added a test case. Not entirely happy with the code - it seems there should be a less complicated way. Suggestions welcome :-)

[amoffat]

LGTM @ecederstrand. Scoping the baked args to the environment-specific Command class is exactly how I would have tried to do it. Good work 👍