Replace magic sed for Python argv[0] with a python wrapper.

[domenkozar]

Magic sed line is something that probably just @aszlig can maintain, so I propose a simplification.

Not sure what the best approach would be, but current exec -a bla also doesn't work.

[spwhitt]

Is my approach missing something? #7931

[domenkozar]

Yeah I still need to review that, thanks for reminding me

[Profpatsch]

(triage) was this solved?

[domenkozar]

Nope.

[FRidh]

We have a solution where we use sitecustomize.py to load and set sys.argv[0] from an environment variable #25985 (comment).

[mmahut]

Are there any updates on this issue, please

[Profpatsch]

I don’t see any magic sed line in the linked code anymore, so I’m gonna close for now.

[aszlig]

@Profpatsch: This is not solved yet, it's just in a different place:

nixpkgs/pkgs/development/interpreters/python/wrap-python.nix

Lines 14 to 51 in c09bc3e

	substitutions.magicalSedExpression = let
	# Looks weird? Of course, it's between single quoted shell strings.
	# NOTE: Order DOES matter here, so single character quotes need to be
	# at the last position.
	quoteVariants = [ "'\"'''\"'" "\"\"\"" "\"" "'\"'\"'" ]; # hey Vim: ''
	mkStringSkipper = labelNum: quote: let
	label = "q${toString labelNum}";
	isSingle = elem quote [ "\"" "'\"'\"'" ];
	endQuote = if isSingle then "[^\\\\]${quote}" else quote;
	in ''
	/^[a-z]?${quote}/ {
	/${quote}${quote}|${quote}.*${endQuote}/{n;br}
	:${label}; n; /^${quote}/{n;br}; /${endQuote}/{n;br}; b${label}
	}
	'';
	# This preamble does two things:
	# * Sets argv[0] to the original application's name; otherwise it would be .foo-wrapped.
	# Python doesn't support `exec -a`.
	# * Adds all required libraries to sys.path via `site.addsitedir`. It also handles *.pth files.
	preamble = ''
	import sys
	import site
	import functools
	sys.argv[0] = '"'$(readlink -f "$f")'"'
	functools.reduce(lambda k, p: site.addsitedir(p, k), ['"$([ -n "$program_PYTHONPATH" ] && (echo "'$program_PYTHONPATH'" | sed "s|:|','|g") || true)"'], site._init_pathinfo())
	'';
	in ''
	1 {
	:r
	/\\$|,$/{N;br}
	/__future__|^ |^ *(#.*)?$/{n;br}
	${concatImapStrings mkStringSkipper quoteVariants}
	/^[^# ]/i ${replaceStrings ["\n"] [";"] preamble}
	}
	'';

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