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# FileHandle

- NAME
- SYNOPSIS
- DESCRIPTION
- SEE ALSO

## 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 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.

`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 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

    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 section on I/O Operators in the perlop manpage 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, the perlfunc manpage, the section on I/O Operators in the perlop manpage.

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