Hello! The holiday spirit brought my attention to SR-237. It seems there hasn't been much activity on this front recently. So I want to propose an approach and take a temperature check here.
IIUC, a gradual migration is preferred (e.g this convo). In a nutshell, we could do that by converting Bash code bit by bit within build-script-impl:
#!/usr/bin/env bash
LIST=(a B hElLo woRlD)
ENV_INPUT_TO_UPPER=False
function sameCaseList() {
python << END
# actual Python implementation
def sameCaseList(i, upper):
if upper:
return [s.upper() for s in i]
else:
return [s.lower() for s in i]
# prepare input
l = "$@".split()
# prepare output
print(' '.join(sameCaseList(l, ${ENV_INPUT_TO_UPPER})))
END
}
for s in $(sameCaseList ${LIST[@]}); do
echo $s
done
Output:
a
b
hello
world
This fictional example demonstrates that, with some finesse, we can write non-trivial Python code that interfaces well with normal Bash. The Python function get input from both the bash function, as well as an environment variable; it also "returns" a value.
Part of the "finesse" is converting Python's output so that it works with Bash, this could include setting "global" or environment variables. This extra effort may add some bloat to trivial Bash functions that exists. But the bloat gets proportionally smaller and smaller as more code converts to Python.
The Python function can perform any "side effects" (writing to file system) as well as the Bash script.
Using this approach, we can rewrite a lot of the smaller functions first. Those with inner dependencies can merge into the same block of Python code. Eventually, there'd be only one Python block left. Then we just change the shebang to use Python and celebrate.
I like this approach because it fits ours need to convert gradually. It also serves as a forcing function to refactoring the existing Bash logic to smaller pieces (tho it already looks pretty good!).
I can't help but think things won't be this simple. So please let me know if I overlooked some complexities. Other kinds of feedbacks are welcome, too!