Speculative Shell Feature Brainstorming Post: 302514403

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The Lounge What is on Your Mind? Speculative Shell Feature Brainstorming Post 302514403 by Corona688 on Friday 15th of April 2011 03:29:19 PM

04-15-2011

Registered User

Another way to handle anonymous files could be similar to the awk way. When you redirect a file in awk, it stays open, referring to the same filename later just gets you the same handle over and over.

Code:

LINE=1
# Read lines from "otherfile" and "cmpfile" one by one, without
# redirecting the entire loop's stdin.
# Also set the close-on-exec flag for files opened in this fashion.
while read LINE <<"otherfile" && read OTHERLINE <<"cmpfile"
do
        if [ "$LINE" != "$OTHERLINE" ]
        then
                echo "Line $LINE doesn't match"
                echo "What would you like to do?"

                read RESPONSE
                case "${RESPONSE}" in
                *)   # todo: something
                      ;;
                 esac
        fi
        ((LINE++))
done

close "cmpfile" "otherfile"

Using << for 'keep the file open' seems a nice opposite of the >> 'append to file' redirection. This breaks the syntax for here-documents though. Not quite sure how to get the FD out of that either, maybe $<"filename" ?

Last edited by Corona688; 04-15-2011 at 04:35 PM..

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LEARN ABOUT DEBIAN

mixin::linewise::readers

Mixin::Linewise::Readers(3pm)				User Contributed Perl Documentation			     Mixin::Linewise::Readers(3pm)

NAME

       Mixin::Linewise::Readers - get linewise readers for strings and filenames

SYNOPSIS

	 package Your::Pkg;
	 use Mixin::Linewise::Readers -readers;

	 sub read_handle {
	   my ($self, $handle) = @_;

	   LINE: while (my $line = $handle->getline) {
	     next LINE if $line =~ /^#/;

	     print "non-comment: $line";
	   }
	 }

       Then:

	 use Your::Pkg;

	 Your::Pkg->read_file($filename);

	 Your::Pkg->read_string($string);

	 Your::Pkg->read_handle($fh);

EXPORTS

       "read_file" and "read_string" are exported by default.  Either can be requested individually, or renamed.  They are generated by
       Sub::Exporter, so consult its documentation for more information.

       Both can be generated with the option "method" which requests that a method other than "read_handle" is called with the created IO::Handle.

   read_file
	 Your::Pkg->read_file($filename);

       If generated, the "read_file" export attempts to open the named file for reading, and then calls "read_handle" on the opened handle.

       Any arguments after $filename are passed along after to "read_handle".

   read_string
	 Your::Pkg->read_string($string);

       If generated, the "read_string" creates an IO::String handle from the given string, and then calls "read_handle" on the opened handle.

       Any arguments after $string are passed along after to "read_handle".

BUGS

       Bugs should be reported via the CPAN bug tracker at

       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Mixin-Linewise>

       For other issues, or commercial enhancement or support, contact the author.

AUTHOR

       Ricardo SIGNES, "<rjbs@cpan.org>"

COPYRIGHT

       Copyright 2008, Ricardo SIGNES.

       This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

perl v5.10.1							    2010-02-14					     Mixin::Linewise::Readers(3pm)