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 ref
erence to a newly created symbol (see the `Symbol' pack
age). 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 `File
Handle' object is destroyed. Otherwise, it is returned to
`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 previ
ously visited position.
If the C function setvbuf() is available, then `FileHan
dle::setvbuf' sets the buffering policy for the FileHan
dle. 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
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 I/O Operators
entry in the perlop manpage except that it's more
readable and can be safely called in an array context
but still returns just one line.
$fh->getlines
This works like <$fh> when called in an array context
to read all the remaining lines in a file, except that
it's more readable. It will also croak() if acciden
tally 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 I/O Operators
entry in the perlop manpage.
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