Dear List,

i found on the emacswiki the following script written in Perl which is
supposed to make emacsclient read from a pipe:

#! /usr/bin/perl

# This script uses emacsclient, be sure to have a running server session.
# A server-session can be started by "M-x server-start".

my $status = system("emacsclient -n --eval '(progn (pop-to-buffer (get-buffer-create \"*piped*\")))'");
if($status!=0){ exit 1; }
while(<STDIN>){
system("emacsclient -n --eval '(with-current-buffer \"*piped*\" (insert \"" . $_ . "\"))'");
}


Now when this script reads a list of emailaddresses for example from
mutt:

From: John Test <john [at] test.org>
From: "William Testtwo" <william testtwo [at] test.test.org>

it gives the following output:

#<buffer *piped*>
*ERROR*: Symbol's value as variable is void: William

everything works normaly if before feeding the output to emacspipe.pl,
i run it through "sed s/\"//g", whereby deleting the double quotes.

There must be something about the interpolation. Maybe somebody has an
idea? I am not an expert at this.

Gabriel

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>>>>> "GS" == Gabriel Striewe <linux [at] gabriel-striewe.de> writes:

GS> my $status = system("emacsclient -n --eval '(progn (pop-to-buffer (get-buffer-create \"*piped*\")))'");
GS> if($status!=0){ exit 1; }
GS> while(<STDIN>){
GS> system("emacsclient -n --eval '(with-current-buffer \"*piped*\" (insert \"" . $_ . "\"))'");
GS> }

a first pass is for you to learn the qq{} alternate quote
operator. escaping " like you do is noisy and tricky. learn about these
in perlop. qq{} is like "" but you can put " inside without
escaping. you can use any delimiter you like but paired {} is among the
best (you can even have nested {} inside without escaping!). so those
lines would look like (untested):

my $status = system( qq{emacsclient -n --eval
'(progn (pop-to-buffer (get-buffer-create "*piped*")))'
});

system( qq{ emacsclient -n --eval
'(with-current-buffer "*piped*" (insert "$_"))'
});

notice how much easier they are to read and you can see the "" are for
emacs lisp and not for perl.

actually i just noticed the first one doesn't to any perl interpolation
so that could use q{} which is like ''. the second one needs double
quotish behavior since it interpolates $_.

another improvement would be to use a named variable in the while which
makes the code easier to read. i stay away from $_ unless it is required
or it has a major win. neither case applies here, so this is
better. also you don't chomp the input line and that may also screw
things up:


while( my $email = <STDIN> ) {
chomp $email ;
system( qq{ emacsclient -n --eval
'(with-current-buffer "*piped*" (insert "$email"))'
});
}

better formatting helps too. that code is now ready for you and others
to understand easily and maintain.

uri

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Uri Guttman ------ uri [at] stemsystems.com -------- http://www.sysarch.com --
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