FileHandle - Supply Object Methods for Filehandles

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

• new
• Creates a FileHandle, which is a reference to a newly created symbol (see the Symbol library module). If it receives any parameters, they are passed to open(). If the open fails, the FileHandle object is destroyed. Otherwise, it is returned to the caller.
• new_from_fd
• Creates a FileHandle like new() does. It requires two parameters, which are passed to fdopen(); if the fdopen() fails, the FileHandle object is destroyed. Otherwise, it is returned to the caller.
• 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 in either Perl form (">", "+<", and so on) or POSIX form ("w", "r+", and so on).
• fdopen
• Like open() except that its first parameter is not a filename but rather a filehandle name, a FileHandle object, or a file descriptor number.
• getpos
• If the C functions fgetpos(3) and fsetpos(3) are available, then getpos() returns an opaque value that represents the current position of the FileHandle, and setpos() uses that value to return to a previously visited position.
• setvbuf
• If the C function setvbuf(3) is available, then 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 setvbuf() must not be modified in any way until the FileHandle is closed or until setvbuf() is called again, or memory corruption may result!

The following supported FileHandle methods are just front ends for the corresponding built-in Perl functions:

The following supported FileHandle methods correspond to Perl special variables:

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

• $fh->print
• See Perl's built-in print function.
• $fh->printf
• See Perl's built-in printf function.
• $fh->getline
• This method works like Perl's <FILEHANDLE> construct, except that it can be safely called in an array context, where it still returns just one line.
• $fh->getlines
• This method works like Perl's <FILEHANDLE> construct when called in an array context to read all remaining lines in a file. It will also croak() if accidentally called in a scalar context.

Bugs

Due to backward compatibility, all filehandles resemble objects of class FileHandle, or actually classes derived from that class. But they aren't. Which means you can't derive your own class from FileHandle and inherit those methods.

While it may look as though the filehandle methods corresponding to the built-in variables are unique to a particular filehandle, currently some of them are not, including the following: