


FileHandle(3p)   Perl Programmers Reference Guide  FileHandle(3p)


NAME
       FileHandle - supply object methods for filehandles

SYNOPSIS
           use FileHandle;

           $fh = new FileHandle;
           if ($fh->open("< file")) {
               print <$fh>;
               $fh->close;
           }

           $fh = new FileHandle "> FOO";
           if (defined $fh) {
               print $fh "bar\n";
               $fh->close;
           }

           $fh = new FileHandle "file", "r";
           if (defined $fh) {
               print <$fh>;
               undef $fh;       # automatically closes the file
           }

           $fh = new FileHandle "file", O_WRONLY|O_APPEND;
           if (defined $fh) {
               print $fh "corge\n";
               undef $fh;       # automatically closes the file
           }

           $pos = $fh->getpos;
           $fh->setpos($pos);

           $fh->setvbuf($buffer_var, _IOLBF, 1024);

           ($readfh, $writefh) = FileHandle::pipe;

           autoflush STDOUT 1;


DESCRIPTION
       NOTE: This class is now a front-end to the IO::* classes.

       `FileHandle::new' creates a `FileHandle', which is a ref-
       erence to a newly created symbol (see the `Symbol' pack-
       age).  If it receives any parameters, they are passed to
       `FileHandle::open'; if the open fails, the `FileHandle'
       object is destroyed.  Otherwise, it is returned to the
       caller.

       `FileHandle::new_from_fd' creates a `FileHandle' like
       `new' does.  It requires two parameters, which are passed
       to `FileHandle::fdopen'; if the fdopen fails, the `File-
       Handle' object is destroyed.  Otherwise, it is returned to



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FileHandle(3p)   Perl Programmers Reference Guide  FileHandle(3p)


       the caller.

       `FileHandle::open' accepts one parameter or two.  With one
       parameter, it is just a front end for the built-in `open'
       function.  With two parameters, the first parameter is a
       filename that may include whitespace or other special
       characters, and the second parameter is the open mode,
       optionally followed by a file permission value.

       If `FileHandle::open' receives a Perl mode string (">",
       "+<", etc.)  or a POSIX fopen() mode string ("w", "r+",
       etc.), it uses the basic Perl `open' operator.

       If `FileHandle::open' is given a numeric mode, it passes
       that mode and the optional permissions value to the Perl
       `sysopen' operator.  For convenience, `FileHandle::import'
       tries to import the O_XXX constants from the Fcntl module.
       If dynamic loading is not available, this may fail, but
       the rest of FileHandle will still work.

       `FileHandle::fdopen' is like `open' except that its first
       parameter is not a filename but rather a file handle name,
       a FileHandle object, or a file descriptor number.

       If the C functions fgetpos() and fsetpos() are available,
       then `FileHandle::getpos' returns an opaque value that
       represents the current position of the FileHandle, and
       `FileHandle::setpos' uses that value to return to a previ-
       ously visited position.

       If the C function setvbuf() is available, then `FileHan-
       dle::setvbuf' sets the buffering policy for the FileHan-
       dle.  The calling sequence for the Perl function is the
       same as its C counterpart, including the macros `_IOFBF',
       `_IOLBF', and `_IONBF', except that the buffer parameter
       specifies a scalar variable to use as a buffer.  WARNING:
       A variable used as a buffer by `FileHandle::setvbuf' must
       not be modified in any way until the FileHandle is closed
       or until `FileHandle::setvbuf' is called again, or memory
       corruption may result!

       See the perlfunc manpage for complete descriptions of each
       of the following supported `FileHandle' methods, which are
       just front ends for the corresponding built-in functions:

           close
           fileno
           getc
           gets
           eof
           clearerr
           seek
           tell




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FileHandle(3p)   Perl Programmers Reference Guide  FileHandle(3p)


       See the perlvar manpage for complete descriptions of each
       of the following supported `FileHandle' methods:

           autoflush
           output_field_separator
           output_record_separator
           input_record_separator
           input_line_number
           format_page_number
           format_lines_per_page
           format_lines_left
           format_name
           format_top_name
           format_line_break_characters
           format_formfeed

       Furthermore, for doing normal I/O you might need these:

       $fh->print
           See the print entry in the perlfunc manpage.

       $fh->printf
           See the printf entry in the perlfunc manpage.

       $fh->getline
           This works like <$fh> described in the I/O Operators
           entry in the perlop manpage except that it's more
           readable and can be safely called in an array context
           but still returns just one line.

       $fh->getlines
           This works like <$fh> when called in an array context
           to read all the remaining lines in a file, except that
           it's more readable.  It will also croak() if acciden-
           tally called in a scalar context.

       There are many other functions available since FileHandle
       is descended from IO::File, IO::Seekable, and IO::Handle.
       Please see those respective pages for documentation on
       more functions.

SEE ALSO
       The IO extension, the perlfunc manpage, the I/O Operators
       entry in the perlop manpage.













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