


IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


NAME
       IO::Compress::Deflate - Write RFC 1950 files/buffers

SYNOPSIS
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           my $status = deflate $input => $output [,OPTS]
               or die "deflate failed: $DeflateError\n";

           my $z = new IO::Compress::Deflate $output [,OPTS]
               or die "deflate failed: $DeflateError\n";

           $z->print($string);
           $z->printf($format, $string);
           $z->write($string);
           $z->syswrite($string [, $length, $offset]);
           $z->flush();
           $z->tell();
           $z->eof();
           $z->seek($position, $whence);
           $z->binmode();
           $z->fileno();
           $z->opened();
           $z->autoflush();
           $z->input_line_number();
           $z->newStream( [OPTS] );

           $z->deflateParams();

           $z->close() ;

           $DeflateError ;

           # IO::File mode

           print $z $string;
           printf $z $format, $string;
           tell $z
           eof $z
           seek $z, $position, $whence
           binmode $z
           fileno $z
           close $z ;

DESCRIPTION
       This module provides a Perl interface that allows writing
       compressed data to files or buffer as defined in RFC 1950.

       For reading RFC 1950 files/buffers, see the companion
       module IO::Uncompress::Inflate.

Functional Interface
       A top-level function, "deflate", is provided to carry out
       "one-shot" compression between buffers and/or files. For



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       finer control over the compression process, see the "OO
       Interface" section.

           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           deflate $input => $output [,OPTS]
               or die "deflate failed: $DeflateError\n";

       The functional interface needs Perl5.005 or better.

   deflate $input => $output [, OPTS]
       "deflate" expects at least two parameters, $input and
       $output.

       The $input parameter

       The parameter, $input, is used to define the source of the
       uncompressed data.

       It can take one of the following forms:

       A filename
            If the $input parameter is a simple scalar, it is
            assumed to be a filename. This file will be opened
            for reading and the input data will be read from it.

       A filehandle
            If the $input parameter is a filehandle, the input
            data will be read from it.  The string '-' can be
            used as an alias for standard input.

       A scalar reference
            If $input is a scalar reference, the input data will
            be read from $$input.

       An array reference
            If $input is an array reference, each element in the
            array must be a filename.

            The input data will be read from each file in turn.

            The complete array will be walked to ensure that it
            only contains valid filenames before any data is
            compressed.

       An Input FileGlob string
            If $input is a string that is delimited by the
            characters "<" and ">" "deflate" will assume that it
            is an input fileglob string. The input is the list of
            files that match the fileglob.

            If the fileglob does not match any files ...

            See File::GlobMapper for more details.



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       If the $input parameter is any other type, "undef" will be
       returned.

       The $output parameter

       The parameter $output is used to control the destination
       of the compressed data. This parameter can take one of
       these forms.

       A filename
            If the $output parameter is a simple scalar, it is
            assumed to be a filename.  This file will be opened
            for writing and the compressed data will be written
            to it.

       A filehandle
            If the $output parameter is a filehandle, the
            compressed data will be written to it.  The string
            '-' can be used as an alias for standard output.

       A scalar reference
            If $output is a scalar reference, the compressed data
            will be stored in $$output.

       An Array Reference
            If $output is an array reference, the compressed data
            will be pushed onto the array.

       An Output FileGlob
            If $output is a string that is delimited by the
            characters "<" and ">" "deflate" will assume that it
            is an output fileglob string. The output is the list
            of files that match the fileglob.

            When $output is an fileglob string, $input must also
            be a fileglob string. Anything else is an error.

       If the $output parameter is any other type, "undef" will
       be returned.

   Notes
       When $input maps to multiple files/buffers and $output is
       a single file/buffer the input files/buffers will be
       stored in $output as a concatenated series of compressed
       data streams.

   Optional Parameters
       Unless specified below, the optional parameters for
       "deflate", "OPTS", are the same as those used with the OO
       interface defined in the "Constructor Options" section
       below.

       "AutoClose => 0|1"
            This option applies to any input or output data



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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


            streams to "deflate" that are filehandles.

            If "AutoClose" is specified, and the value is true,
            it will result in all input and/or output filehandles
            being closed once "deflate" has completed.

            This parameter defaults to 0.

       "BinModeIn => 0|1"
            When reading from a file or filehandle, set "binmode"
            before reading.

            Defaults to 0.

       "Append => 0|1"
            TODO

   Examples
       To read the contents of the file "file1.txt" and write the
       compressed data to the file "file1.txt.1950".

           use strict ;
           use warnings ;
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           my $input = "file1.txt";
           deflate $input => "$input.1950"
               or die "deflate failed: $DeflateError\n";

       To read from an existing Perl filehandle, $input, and
       write the compressed data to a buffer, $buffer.

           use strict ;
           use warnings ;
           use IO::Compress::Deflate qw(deflate $DeflateError) ;
           use IO::File ;

           my $input = new IO::File "<file1.txt"
               or die "Cannot open 'file1.txt': $!\n" ;
           my $buffer ;
           deflate $input => \$buffer
               or die "deflate failed: $DeflateError\n";

       To compress all files in the directory "/my/home" that
       match "*.txt" and store the compressed data in the same
       directory

           use strict ;
           use warnings ;
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           deflate '</my/home/*.txt>' => '<*.1950>'
               or die "deflate failed: $DeflateError\n";




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       and if you want to compress each file one at a time, this
       will do the trick

           use strict ;
           use warnings ;
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           for my $input ( glob "/my/home/*.txt" )
           {
               my $output = "$input.1950" ;
               deflate $input => $output
                   or die "Error compressing '$input': $DeflateError\n";
           }

OO Interface
   Constructor
       The format of the constructor for "IO::Compress::Deflate"
       is shown below

           my $z = new IO::Compress::Deflate $output [,OPTS]
               or die "IO::Compress::Deflate failed: $DeflateError\n";

       It returns an "IO::Compress::Deflate" object on success
       and undef on failure.  The variable $DeflateError will
       contain an error message on failure.

       If you are running Perl 5.005 or better the object, $z,
       returned from IO::Compress::Deflate can be used exactly
       like an IO::File filehandle.  This means that all normal
       output file operations can be carried out with $z.  For
       example, to write to a compressed file/buffer you can use
       either of these forms

           $z->print("hello world\n");
           print $z "hello world\n";

       The mandatory parameter $output is used to control the
       destination of the compressed data. This parameter can
       take one of these forms.

       A filename
            If the $output parameter is a simple scalar, it is
            assumed to be a filename. This file will be opened
            for writing and the compressed data will be written
            to it.

       A filehandle
            If the $output parameter is a filehandle, the
            compressed data will be written to it.  The string
            '-' can be used as an alias for standard output.

       A scalar reference
            If $output is a scalar reference, the compressed data
            will be stored in $$output.



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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


       If the $output parameter is any other type,
       "IO::Compress::Deflate"::new will return undef.

   Constructor Options
       "OPTS" is any combination of the following options:

       "AutoClose => 0|1"
            This option is only valid when the $output parameter
            is a filehandle. If specified, and the value is true,
            it will result in the $output being closed once
            either the "close" method is called or the
            "IO::Compress::Deflate" object is destroyed.

            This parameter defaults to 0.

       "Append => 0|1"
            Opens $output in append mode.

            The behaviour of this option is dependent on the type
            of $output.

            o    A Buffer

                 If $output is a buffer and "Append" is enabled,
                 all compressed data will be append to the end if
                 $output. Otherwise $output will be cleared
                 before any data is written to it.

            o    A Filename

                 If $output is a filename and "Append" is
                 enabled, the file will be opened in append mode.
                 Otherwise the contents of the file, if any, will
                 be truncated before any compressed data is
                 written to it.

            o    A Filehandle

                 If $output is a filehandle, the file pointer
                 will be positioned to the end of the file via a
                 call to "seek" before any compressed data is
                 written to it.  Otherwise the file pointer will
                 not be moved.

            This parameter defaults to 0.

       "Merge => 0|1"
            This option is used to compress input data and append
            it to an existing compressed data stream in $output.
            The end result is a single compressed data stream
            stored in $output.

            It is a fatal error to attempt to use this option
            when $output is not an RFC 1950 data stream.



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            There are a number of other limitations with the
            "Merge" option:

            1.   This module needs to have been built with zlib
                 1.2.1 or better to work. A fatal error will be
                 thrown if "Merge" is used with an older version
                 of zlib.

            2.   If $output is a file or a filehandle, it must be
                 seekable.

            This parameter defaults to 0.

       -Level
            Defines the compression level used by zlib. The value
            should either be a number between 0 and 9 (0 means no
            compression and 9 is maximum compression), or one of
            the symbolic constants defined below.

               Z_NO_COMPRESSION
               Z_BEST_SPEED
               Z_BEST_COMPRESSION
               Z_DEFAULT_COMPRESSION

            The default is Z_DEFAULT_COMPRESSION.

            Note, these constants are not imported by
            "IO::Compress::Deflate" by default.

                use IO::Compress::Deflate qw(:strategy);
                use IO::Compress::Deflate qw(:constants);
                use IO::Compress::Deflate qw(:all);

       -Strategy
            Defines the strategy used to tune the compression.
            Use one of the symbolic constants defined below.

               Z_FILTERED
               Z_HUFFMAN_ONLY
               Z_RLE
               Z_FIXED
               Z_DEFAULT_STRATEGY

            The default is Z_DEFAULT_STRATEGY.

       "Strict => 0|1"
            This is a placeholder option.

   Examples
       TODO

Methods
   print
       Usage is



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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


           $z->print($data)
           print $z $data

       Compresses and outputs the contents of the $data
       parameter. This has the same behaviour as the "print"
       built-in.

       Returns true if successful.

   printf
       Usage is

           $z->printf($format, $data)
           printf $z $format, $data

       Compresses and outputs the contents of the $data
       parameter.

       Returns true if successful.

   syswrite
       Usage is

           $z->syswrite $data
           $z->syswrite $data, $length
           $z->syswrite $data, $length, $offset

       Compresses and outputs the contents of the $data
       parameter.

       Returns the number of uncompressed bytes written, or
       "undef" if unsuccessful.

   write
       Usage is

           $z->write $data
           $z->write $data, $length
           $z->write $data, $length, $offset

       Compresses and outputs the contents of the $data
       parameter.

       Returns the number of uncompressed bytes written, or
       "undef" if unsuccessful.

   flush
       Usage is

           $z->flush;
           $z->flush($flush_type);

       Flushes any pending compressed data to the output
       file/buffer.



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       This method takes an optional parameter, $flush_type, that
       controls how the flushing will be carried out. By default
       the $flush_type used is "Z_FINISH". Other valid values for
       $flush_type are "Z_NO_FLUSH", "Z_SYNC_FLUSH",
       "Z_FULL_FLUSH" and "Z_BLOCK". It is strongly recommended
       that you only set the "flush_type" parameter if you fully
       understand the implications of what it does - overuse of
       "flush" can seriously degrade the level of compression
       achieved. See the "zlib" documentation for details.

       Returns true on success.

   tell
       Usage is

           $z->tell()
           tell $z

       Returns the uncompressed file offset.

   eof
       Usage is

           $z->eof();
           eof($z);

       Returns true if the "close" method has been called.

   seek
           $z->seek($position, $whence);
           seek($z, $position, $whence);

       Provides a sub-set of the "seek" functionality, with the
       restriction that it is only legal to seek forward in the
       output file/buffer.  It is a fatal error to attempt to
       seek backward.

       Empty parts of the file/buffer will have NULL (0x00) bytes
       written to them.

       The $whence parameter takes one the usual values, namely
       SEEK_SET, SEEK_CUR or SEEK_END.

       Returns 1 on success, 0 on failure.

   binmode
       Usage is

           $z->binmode
           binmode $z ;

       This is a noop provided for completeness.





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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


   opened
           $z->opened()

       Returns true if the object currently refers to a opened
       file/buffer.

   autoflush
           my $prev = $z->autoflush()
           my $prev = $z->autoflush(EXPR)

       If the $z object is associated with a file or a
       filehandle, this method returns the current autoflush
       setting for the underlying filehandle. If "EXPR" is
       present, and is non-zero, it will enable flushing after
       every write/print operation.

       If $z is associated with a buffer, this method has no
       effect and always returns "undef".

       Note that the special variable $| cannot be used to set or
       retrieve the autoflush setting.

   input_line_number
           $z->input_line_number()
           $z->input_line_number(EXPR)

       This method always returns "undef" when compressing.

   fileno
           $z->fileno()
           fileno($z)

       If the $z object is associated with a file or a
       filehandle, "fileno" will return the underlying file
       descriptor. Once the "close" method is called "fileno"
       will return "undef".

       If the $z object is is associated with a buffer, this
       method will return "undef".

   close
           $z->close() ;
           close $z ;

       Flushes any pending compressed data and then closes the
       output file/buffer.

       For most versions of Perl this method will be
       automatically invoked if the IO::Compress::Deflate object
       is destroyed (either explicitly or by the variable with
       the reference to the object going out of scope). The
       exceptions are Perl versions 5.005 through 5.00504 and
       5.8.0. In these cases, the "close" method will be called
       automatically, but not until global destruction of all



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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


       live objects when the program is terminating.

       Therefore, if you want your scripts to be able to run on
       all versions of Perl, you should call "close" explicitly
       and not rely on automatic closing.

       Returns true on success, otherwise 0.

       If the "AutoClose" option has been enabled when the
       IO::Compress::Deflate object was created, and the object
       is associated with a file, the underlying file will also
       be closed.

   newStream([OPTS])
       Usage is

           $z->newStream( [OPTS] )

       Closes the current compressed data stream and starts a new
       one.

       OPTS consists of any of the the options that are available
       when creating the $z object.

       See the "Constructor Options" section for more details.

   deflateParams
       Usage is

           $z->deflateParams

       TODO

Importing
       A number of symbolic constants are required by some
       methods in "IO::Compress::Deflate". None are imported by
       default.

       :all Imports "deflate", $DeflateError and all symbolic
            constants that can be used by
            "IO::Compress::Deflate". Same as doing this

                use IO::Compress::Deflate qw(deflate $DeflateError :constants) ;

       :constants
            Import all symbolic constants. Same as doing this

                use IO::Compress::Deflate qw(:flush :level :strategy) ;

       :flush
            These symbolic constants are used by the "flush"
            method.





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                Z_NO_FLUSH
                Z_PARTIAL_FLUSH
                Z_SYNC_FLUSH
                Z_FULL_FLUSH
                Z_FINISH
                Z_BLOCK

       :level
            These symbolic constants are used by the "Level"
            option in the constructor.

                Z_NO_COMPRESSION
                Z_BEST_SPEED
                Z_BEST_COMPRESSION
                Z_DEFAULT_COMPRESSION

       :strategy
            These symbolic constants are used by the "Strategy"
            option in the constructor.

                Z_FILTERED
                Z_HUFFMAN_ONLY
                Z_RLE
                Z_FIXED
                Z_DEFAULT_STRATEGY

EXAMPLES
   Apache::GZip Revisited
       See IO::Compress::FAQ

   Working with Net::FTP
       See IO::Compress::FAQ

SEE ALSO
       Compress::Zlib, IO::Compress::Gzip,
       IO::Uncompress::Gunzip, IO::Uncompress::Inflate,
       IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
       IO::Compress::Bzip2, IO::Uncompress::Bunzip2,
       IO::Compress::Lzop, IO::Uncompress::UnLzop,
       IO::Compress::Lzf, IO::Uncompress::UnLzf,
       IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress

       Compress::Zlib::FAQ

       File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib

       For RFC 1950, 1951 and 1952 see
       http://www.faqs.org/rfcs/rfc1950.html,
       http://www.faqs.org/rfcs/rfc1951.html and
       http://www.faqs.org/rfcs/rfc1952.html

       The zlib compression library was written by Jean-loup
       Gailly gzip@prep.ai.mit.edu and Mark Adler
       madler@alumni.caltech.edu.



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IO::Compress::DefPerl(Programmers RefereIO::Compress::Deflate(3p)


       The primary site for the zlib compression library is
       http://www.zlib.org.

       The primary site for gzip is http://www.gzip.org.

AUTHOR
       This module was written by Paul Marquess, pmqs@cpan.org.

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2009 Paul Marquess. All rights
       reserved.

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








































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