From: Jeff King <peff@peff.net>
Date: Fri, 06 Feb 2009 20:30:37 GMT
Subject: Re: [PATCH] add -p: import Term::ReadKey with 'require'
Message-ID: <20090206203037.GB19959@coredump.intra.peff.net>
In-Reply-To: <1233948601-4828-1-git-send-email-trast@student.ethz.ch>

On Fri, Feb 06, 2009 at 08:30:01PM +0100, Thomas Rast wrote:

> The code below _seems_ to work.  I have to say that beyond the
> 'require', it's all voodoo to me, so I'd appreciate an extra-careful
> check.
> [...]
> +sub ReadMode;
> +sub ReadKey;

I believe it is fine. The tricky thing is that perl's parsing is
dependent on what functions have been defined. So it is OK to say

  ReadKey 0;

if a subroutine ReadKey has been defined, but otherwise it generates a
warning about using the bareword as a function. However

  ReadKey(0);

parses unambiguously, so it is always OK, even if no subroutine has yet
been defined.

So with the "use" code, Term::ReadKey had already been loaded when
parsing the bit about ReadKey. But now it is loaded at run-time, so at
parse time we don't know about that subroutine yet. So your options are
to forward-declare the subroutines (which you did), or to change calls
to the obvious function-like form.

> -		use Term::ReadKey;
> +		require Term::ReadKey;
> +		Term::ReadKey->import;

And the two added lines are the exact runtime equivalent of the deleted
line (note that you could also skip the import and just call
Term::ReadKey::ReadKey by its full name).

-Peff