gistfile1.txt

From: Sam Stephenson <sstephenson@gmail.com>
Subject: Re: ruby-build hint
Date: Sun, 10 Feb 2013 12:25:56 -0600
To: Michał Papis <mpapis@gmail.com>

Hi Michał,

Thanks for the email.

You're right that `[[` is not POSIX sh-compliant. Nor are the following
other constructs in ruby-build:

* String range operator (`"${arg:0:1}"`, `"${arg:1:1}"`, etc.)
* Arrays (`$OPTIONS`, `$words`, `$fetch_args`, `$make_args`)
* Variable indirection (`"${!PACKAGE_CONFIGURE_OPTS}"`, etc.)
* `declare -f` and `$FUNCNAME`
* `type` built-in
* stderr/stdout redirection using `&>/dev/null`
* Escaped character syntax (`$'\033'`)

And certainly there are more. These are just the ones I found making a
quick pass over the source code.

It's fine, though: ruby-build is a Bash program and doesn't claim to be
sh-compliant. Hence the explicit `#!/usr/bin/env bash` shebang.

As a rule I tend to prefer `[` to `[[` because the semantics are
simpler for me to remember, not because it is sh-compliant. In
particular, I prefer the way `[` behaves with `set -e`. In this
instance, I have made an exception because I find glob matching with
`[[` to be far less awkward and more readable than a single-clause
`case` statement.

cheers,
-sam

On Feb 9, 2013, at 11:30 PM, Michał Papis <mpapis@gmail.com> wrote:

> Hi
> 
> I thought making this an public ticket could be unappropriate those I
> mail you directly instead.
> 
> I was just reading ruby-build code and found
> https://github.com/sstephenson/ruby-build/commit/3c6fa3901c89077697c9067d4de743bf37390c9c
> - so far the code all looked SH compatible (using '[' instead of 
> '[[') but this change introduces '[['' which requires something more 
> over pure SH code.
> 
> You can easily replace this code with:
> 
>     [ "$(uname -s)" = "Darwin" ] &&
>     [ "$(openssl version 2>/dev/null || true)" = "OpenSSL 0.9.8r 8 Feb 2011" ] &&
>     case "$RUBY_CONFIGURE_OPTS" in
>       *--with-openssl-dir=*) return 1;;
>     esac
> 
> which will make it back more pure SH.
> 
> Cheers,
> Michal
>