man IO::File () - supply object methods for filehandles


IO::File - supply object methods for filehandles


    use IO::File;

    $fh = new IO::File;
    if ($fh->open("< file")) {
        print <$fh>;

    $fh = new IO::File "> file";
    if (defined $fh) {
        print $fh "bar\n";

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

    $fh = new IO::File "file", O_WRONLY|O_APPEND;
    if (defined $fh) {
        print $fh "corge\n";

        $pos = $fh->getpos;

        undef $fh;       # automatically closes the file

    autoflush STDOUT 1;


CWIO::File inherits from CWIO::Handle and CWIO::Seekable. It extends these classes with methods that are specific to file handles.


Creates an CWIO::File. If it receives any parameters, they are passed to the method CWopen; if the open fails, the object is destroyed. Otherwise, it is returned to the caller.
Creates an CWIO::File opened for read/write on a newly created temporary file. On systems where this is possible, the temporary file is anonymous (i.e. it is unlinked after creation, but held open). If the temporary file cannot be created or opened, the CWIO::File object is destroyed. Otherwise, it is returned to the caller.


CWopen accepts one, two or three parameters. With one parameter, it is just a front end for the built-in CWopen function. With two or three 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 CWIO::File::open receives a Perl mode string (">, +<, etc.) or an ANSI C fopen() mode string (w, r+", etc.), it uses the basic Perl CWopen operator (but protects any special characters). If CWIO::File::open is given a numeric mode, it passes that mode and the optional permissions value to the Perl CWsysopen operator. The permissions default to 0666. If CWIO::File::open is given a mode that includes the CW: character, it passes all the three arguments to the three-argument CWopen operator. For convenience, CWIO::File exports the O_XXX constants from the Fcntl module, if this module is available.
binmode( [LAYER] )
CWbinmode sets CWbinmode on the underlying CWIO object, as documented in CWperldoc -f binmode. CWbinmode accepts one optional parameter, which is the layer to be passed on to the CWbinmode call.


Some operating systems may perform CWIO::File::new() or CWIO::File::open() on a directory without errors. This behavior is not portable and not suggested for use. Using CWopendir() and CWreaddir() or CWIO::Dir are suggested instead.


perlfunc, I/O Operators in perlop, IO::Handle, IO::Seekable, IO::Dir


Derived from by Graham Barr <>.