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';
SEE ALSO¶
The Inline::Files::Virtual module
The Filter::Util::Call module
BUGS ADDED BY¶
Alberto Simoes (ambs@cpan.org)
UNWITTING PAWN OF AN AUTHOR¶
Damian Conway (damian@conway.org)
EVIL MASTERMIND BEHIND IT ALL¶
Brian Ingerson (INGY@cpan.org)
COPYRIGHT¶
Copyright (c) 2001-2009. Damian Conway. All rights reserved.
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
