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Re: [Groff] conditional for file existence?
From: |
Gaius Mulley |
Subject: |
Re: [Groff] conditional for file existence? |
Date: |
16 Jul 2003 23:12:16 +0100 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 |
Werner LEMBERG <address@hidden> writes:
> > Is there a way to check if a filename names an existent file?
>
> No. You are the first one who asks this question here.
>
> Perhaps we should do the same route as TeX, namely adding .openr,
> .read, and a new operator to .if:
>
> .openr <stream> <file>
> .read <stream> <string variable>
> .if f <stream>
>
> `openr' opens a file for reading. It does *not* produce an error.
> [Use the `close' request to undefine the stream handle.]
>
> `read' gets a line (in text mode; stripping the final newline) from a
> stream and puts it into a string variable.
>
> The new conditional operator `f' returns zero if either the stream is
> not open or we are at EOF.
>
> Both `read' and `if f' return an error if the specified stream
> doesn't exist.
>
> A file test for file foo.bar would then look like this:
>
> .open FILE foo.bar
> .if f FILE \{\
> . close FILE
> . so foo.bar
> .\}
>
> For a zero-length file, `if f' will be true before the first call to
> `read' but not afterwards.
>
> Any volunteer to implement?
>
I like this concept - it sounds useful and neat. However I'm still
fighting tags and environments..
Gaius