Thread (20 messages) 20 messages, 5 authors, 2019-06-19

Re: [PATCH v2 01/10] t: add helper to convert object IDs to paths

From: Jeff King <hidden>
Date: 2019-06-18 17:04:19

On Tue, Jun 18, 2019 at 06:15:46PM +0200, Johannes Schindelin wrote:
quoted
And looking through this patch series, I see a gazillion of *new*
process substitutions $(test_something...) and $(basename $whatever).
Can't we do something about it?
I wish there was. Unix shell scripting has not evolved much in the past,
what, 3 decades? So I don't really see a way to "pass variables by
reference" to shell functions, short of calling `eval` (which buys
preciously little as it _also_ has to spawn a new process [*1*]).
Really? An eval can impact the caller's state, so it _can't_ happen in a
sub-process in most cases.

E.g., if I run this:

-- >8 --
#!/bin/sh

# usage: test_oid_to_path <var> <oid>
# to set the variable <var> in the caller's environment to the path of <oid>
test_oid_to_path() {
	path="${2%${2#??}}/${2#??}"
	eval "$1=\$path"
}

test_oid_to_path foo 1234abcd
echo foo: $foo
-- >8 --

it all happens in a single process, under both bash and dash.

-Peff
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