


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


NAME
       FileHandle - supply object methods for filehandles

SYNOPSIS
           use FileHandle;

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

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

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

           $fh = FileHandle->new("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
       reference to a newly created symbol (see the "Symbol"
       package).  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
       "FileHandle" object is destroyed.  Otherwise, it is
       returned to the caller.



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


       "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
       previously visited position.

       If the C function setvbuf() is available, then
       "FileHandle::setvbuf" sets the buffering policy for the
       FileHandle.  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 perlfunc 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

       See perlvar for complete descriptions of each of the



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


       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 "print" in perlfunc.

       $fh->printf
           See "printf" in perlfunc.

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

       $fh->getlines
           This works like <$fh> when called in a list context to
           read all the remaining lines in a file, except that
           it's more readable.  It will also croak() if
           accidentally 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, perlfunc, "I/O Operators" in perlop.















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