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

["SZEDER Gábor" <szeder.dev@gmail.com>]

On Tue, Jun 18, 2019 at 06:15:46PM +0200, Johannes Schindelin wrote:
> > Regardless of how it is implemented, I have another gripe with this
> > helper: the way it must be used requires a process: $(test_out_to_path
> > $foo)
> 
> Indeed.
> 
> > 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*]).

> Footnote *1*: Theoretically, it could be a *ton* faster by using threads
> on Windows. But threads are pretty much an afterthought on Unix/Linux, so
> no mainstream POSIX shell supports this. They all `fork()` to interpret an
> `eval` as far as I can tell.

'eval' doesn't fork().  It can't possibly fork(), because if it did,
then any variables set in the eval-ed code snippet couldn't be visible
outside the 'eval'.