FileHandle - supply object methods for filehandles

- 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 print in the perlfunc manpage.

$fh->printf

  See printf in the perlfunc manpage.

$fh->getline

  This works like <$fh> described in 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, I/O Operators in the perlop manpage.

FileHandle - supply object methods for filehandles