Inline::Files(3)

User Contributed Perl Documentation

Inline::Files(3)

NAME¶

Inline::Files - Multiple virtual files at the end of your code

VERSION¶

This document describes version 0.68 of Inline::Files, released July 23, 2011.

SYNOPSIS¶

    use Inline::Files;
    my Code $here;
    # etc.
    # etc.
    # etc.
    __FOO__
    This is a virtual file at the end
    of the data
    
    __BAR__
    This is another
    virtual
    file
    __FOO__
    This is yet another 
    such file

WARNING¶

It is possible that this module may overwrite the source code in files that use it. To protect yourself against this possibility, you are strongly advised to use the "-backup" option described in "Safety first".

This module is still experimental. Regardless of whether you use "-backup" or not, by using this module you agree that the authors will b<under no circumstances> be responsible for any loss of data, code, time, money, or limbs, or for any other disadvantage incurred as a result of using Inline::Files.

DESCRIPTION¶

Inline::Files generalizes the notion of the "__DATA__" marker and the associated "<DATA>" filehandle, to an arbitrary number of markers and associated filehandles.

When you add the line:

    use Inline::Files;

to a source file you can then specify an arbitrary number of distinct virtual files at the end of the code. Each such virtual file is marked by a line of the form:

    __SOME_SYMBOL_NAME_IN_UPPER_CASE__

The following text -- up to the next such marker -- is treated as a file, whose (pseudo-)name is available as an element of the package array @SOME_SYMBOL_NAME_IN_UPPER_CASE. The name of the first virtual file with this marker is also available as the package scalar $SOME_SYMBOL_NAME_IN_UPPER_CASE.

The filehandle of the same name is magical -- just like "ARGV" -- in that it automatically opens itself when first read. Furthermore -- just like "ARGV" -- the filehandle re-opens itself to the next appropriate virtual file (by "shift"-ing the first element of @SOME_SYMBOL_NAME_IN_UPPER_CASE into $SOME_SYMBOL_NAME_IN_UPPER_CASE) whenever it reaches EOF.

So, just as with "ARGV", you can treat all the virtual files associated with a single symbol either as a single, multi-part file:

    use Inline::Files;
    while (<FILE>) {
        print "$FILE: $_";
    }
    __FILE__
    File 1
    here
    __FILE__
    File 2
    here
    __OTHER_FILE__
    Other file 1
    __FILE__
    File 3
    here

or as a series of individual files:

    use Inline::Files;
    foreach $filename (@FILE) {
        open HANDLE, $filename;
        print "<<$filename>>\n";
        while (<HANDLE>) {
            print;
        }
    }
    __FILE__
    File 1
    here
    __FILE__
    File 2
    here
    __OTHER_FILE__
    Other file 1
    __FILE__
    File 3
    here

Note that these two examples completely ignore the lines:

    __OTHER_FILE__
    Other file 1

which would be accessed via the "OTHER_FILE" filehandle.

Unlike "<ARGV>"/@ARGV/$ARGV, Inline::Files also makes use of the hash associated with an inline file's symbol. That is, when you create an inline file with a marker "__WHATEVER__", the hash %WHATEVER will contain information about that file. That information is:

$WHATEVER{file}: The name of the disk file in which the inlined "__WHATEVER__" files were defined;
$WHATEVER{line}: The line (starting from 1) at which the current inline "__WHATEVER__" file being accessed by "<WHATEVER>" started.
$WHATEVER{offset}: The byte offset (starting from 0) at which the current inline "__WHATEVER__" file being accessed by "<WHATEVER>" started.
$WHATEVER{writable}: Whether the the current inline file being accessed by "<WHATEVER>" is opened for output.

The hash and its elements are read-only and the entry values are only meaningful when the corresponding filehandle is open.

Writable virtual files¶

If the source file that uses Inline::Files is itself writable, then the virtual files it contains may also be opened for write access. For example, here is a very simple persistence mechanism:

    use Inline::Files;
    use Data::Dumper;
    open CACHE or die $!;   # read access (uses $CACHE to locate file)
    eval join "", <CACHE>;
    close CACHE or die $!;
    print "\$var was '$var'\n";
    while (<>) {
        chomp;
        $var = $_;
        print "\$var now '$var'\n";
    }
    open CACHE, ">$CACHE" or die $!;    # write access
    print CACHE Data::Dumper->Dump([$var],['var']);
    close CACHE or die $!;
    __CACHE__
    $var = 'Original value';

Unlike "ARGV", if a virtual file is part of a writable file and is automagically opened, it is opened for full read/write access. So the above example, could be even simpler:

    use Inline::Files;
    use Data::Dumper;
    eval join "", <CACHE>;      # Automagically opened
    print "\$var was '$var'\n";
    while (<>) {
        chomp;
        $var = $_;
        print "\$var now '$var'\n";
    }
    seek CACHE, 0, 0;
    print CACHE Data::Dumper->Dump([$var],['var']);
    __CACHE__
    $var = 'Original value';

In either case, the original file is updated only at the end of execution, on an explicit "close" of the virtual file's handle, or when "Inline::Files::Virtual::vf_save" is explicitly called.

Creating new Inline files on the fly.¶

You can also open up new Inline output files at run time. Simply use the open function with a valid new Inline file handle name and no file name. Like this:

    use Inline::Files;
    open IFILE, '>';
    print IFILE "This line will be placed into a new Inline file\n";
    print IFILE "which is marked by '__IFILE__'\n";

Safety first¶

Because Inline::Files handles are often read-write, it's possible to accidentally nuke your hard-won data. But Inline::Files can save you from yourself.

If Inline::Files is loaded with the "-backup" option:

    use Inline::Files -backup;

then the source file that uses it is backed up before the inline files are extracted. The backup file is the name of the source file with the suffix ".bak" appended.

You can also specify a different name for the backup file, by associating that name with the "-backup" flag:

    use Inline::Files -backup => '/tmp/sauve_qui_peut';

UNWITTING PAWN OF AN AUTHOR¶

Damian Conway (damian@conway.org)

EVIL MASTERMIND BEHIND IT ALL¶

Brian Ingerson (INGY@cpan.org)

COPYRIGHT¶

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

See http://www.perl.com/perl/misc/Artistic.html

2011-07-23

perl v5.16.3