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.