User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101
            Thunderbird/24.5.0
MIME-Version: 1.0
References: <537E212E.2030607@morningstar2.co.uk>
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
Content-Transfer-Encoding: 7bit
Received-SPF: None (: nag.co.uk does not designate permitted sender hosts)
Message-ID:  <537E5311.3020302@nag.co.uk>
Date:         Thu, 22 May 2014 20:42:09 +0100
Reply-To: Mailing list for the LaTeX3 project
              <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
Sender: Mailing list for the LaTeX3 project <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
From: David Carlisle <davidc@NAG.CO.UK>
Subject: Re: Reading from the system (pipe input)
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
In-Reply-To:  <537E212E.2030607@morningstar2.co.uk>
Precedence: list
Envelope-To: <rainer.schoepf@GMX.NET>
Status: R

On 22/05/2014 17:09, Joseph Wright wrote:
> Hello all,
>
> Currently, we have \ior_open:Nn for reading from a file, but no defined
> interface for using the 'pipe' shell escape provided by pdfTeX. As we
> forbid spaces in file names,


why do we do that? Spaces in filenames always seem like an abomination 
to me.
But that seems to be a relic on the 1970s I've noticed that people who 
started using
computers this century don't seem to think anything of using a 
descriptive phrase
as a filename...

Shouldn't we just allow spaces (and leading | or any other system 
dependent special
syntax) just surrounding any user supplied name by " " to keep it together?


> something like
>
>    \ior_open:Nn \g_some_ior {"|kpsewhich~-all~file.tex"}

why not simply

ior_open:Nn \g_some_ior {|kpsewhich~-all~file.tex}

and let web2c worry about the fact it isn't a real file?


>
> fails with an error. A defined interface("\ior_pipe:Nn") has been
> suggested
> (http://chat.stackexchange.com/transcript/message/15666333#15666333).
>
> Thoughts on the concept/naming/etc.? Note that this is opening a
> pseudo-file so does need to be related in some way to \ior_open:Nn.

David