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Under GNU General Public License
2024-12-12 17:00 @18.119.165.105 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
Dpkg::Compression::FileHandle(3perl) libdpkg-perl Dpkg::Compression::FileHandle(3perl)
NAME
Dpkg::Compression::FileHandle - class dealing transparently with file compression
SYNOPSIS
use Dpkg::Compression::FileHandle;
my ($fh, @lines);
$fh = Dpkg::Compression::FileHandle->new(filename => 'sample.gz');
print $fh "Something\n";
close $fh;
$fh = Dpkg::Compression::FileHandle->new();
open($fh, '>', 'sample.bz2');
print $fh "Something\n";
close $fh;
$fh = Dpkg::Compression::FileHandle->new();
$fh->open('sample.xz', 'w');
$fh->print("Something\n");
$fh->close();
$fh = Dpkg::Compression::FileHandle->new(filename => 'sample.gz');
@lines = <$fh>;
close $fh;
$fh = Dpkg::Compression::FileHandle->new();
open($fh, '<', 'sample.bz2');
@lines = <$fh>;
close $fh;
$fh = Dpkg::Compression::FileHandle->new();
$fh->open('sample.xz', 'r');
@lines = $fh->getlines();
$fh->close();
DESCRIPTION
Dpkg::Compression::FileHandle is a class that can be used like any filehandle and that
deals transparently with compressed files. By default, the compression scheme is guessed
from the filename but you can override this behaviour with the method "set_compression".
If you don't open the file explicitly, it will be auto-opened on the first read or write
operation based on the filename set at creation time (or later with the "set_filename"
method).
Once a file has been opened, the filehandle must be closed before being able to open
another file.
STANDARD FUNCTIONS
The standard functions acting on filehandles should accept a Dpkg::Compression::FileHandle
object transparently including "open" (only when using the variant with 3 parameters),
"close", "binmode", "eof", "fileno", "getc", "print", "printf", "read", "sysread", "say",
"write", "syswrite", "seek", "sysseek", "tell".
Note however that "seek" and "sysseek" will only work on uncompressed files as compressed
files are really pipes to the compressor programs and you can't seek on a pipe.
FileHandle METHODS
The class inherits from IO::File so all methods that work on this class should work for
Dpkg::Compression::FileHandle too. There may be exceptions though.
PUBLIC METHODS
$fh = Dpkg::Compression::FileHandle->new(%opts)
Creates a new filehandle supporting on-the-fly compression/decompression. Supported
options are "filename", "compression", "compression_level" (see respective set_*
functions) and "add_comp_ext". If "add_comp_ext" evaluates to true, then the extension
corresponding to the selected compression scheme is automatically added to the
recorded filename. It's obviously incompatible with automatic detection of the
compression method.
$fh->ensure_open($mode, %opts)
Ensure the file is opened in the requested mode ("r" for read and "w" for write). The
options are passed down to the compressor's spawn() call, if one is used. Opens the
file with the recorded filename if needed. If the file is already open but not in the
requested mode, then it errors out.
$fh->set_compression($comp)
Defines the compression method used. $comp should one of the methods supported by
Dpkg::Compression or "none" or "auto". "none" indicates that the file is uncompressed
and "auto" indicates that the method must be guessed based on the filename extension
used.
$fh->set_compression_level($level)
Indicate the desired compression level. It should be a value accepted by the function
"compression_is_valid_level" of Dpkg::Compression.
$fh->set_filename($name, [$add_comp_ext])
Use $name as filename when the file must be opened/created. If $add_comp_ext is
passed, it indicates whether the default extension of the compression method must be
automatically added to the filename (or not).
$file = $fh->get_filename()
Returns the filename that would be used when the filehandle must be opened (both in
read and write mode). This function errors out if "add_comp_ext" is enabled while the
compression method is set to "auto". The returned filename includes the extension of
the compression method if "add_comp_ext" is enabled.
$ret = $fh->use_compression()
Returns "0" if no compression is used and the compression method used otherwise. If
the compression is set to "auto", the value returned depends on the extension of the
filename obtained with the get_filename method.
$real_fh = $fh->get_filehandle()
Returns the real underlying filehandle. Useful if you want to pass it along in a
derived class.
DERIVED CLASSES
If you want to create a class that inherits from Dpkg::Compression::FileHandle you must be
aware that the object is a reference to a GLOB that is returned by Symbol::gensym() and as
such it's not a HASH.
You can store internal data in a hash but you have to use "*$self-"{...}> to access the
associated hash like in the example below:
sub set_option {
my ($self, $value) = @_;
*$self->{option} = $value;
}
CHANGES
Version 1.01 (dpkg 1.17.11)
New argument: $fh->ensure_open() accepts an %opts argument.
Version 1.00 (dpkg 1.15.6)
Mark the module as public.
1.21.1 2024-02-23 Dpkg::Compression::FileHandle(3perl)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-12-12 17:00 @18.119.165.105 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)