Current File : //usr/share/perl/5.38.2/FileHandle.pm
package FileHandle;
use 5.006;
use strict;
our($VERSION, @ISA, @EXPORT, @EXPORT_OK);
$VERSION = "2.05";
require IO::File;
@ISA = qw(IO::File);
@EXPORT = qw(_IOFBF _IOLBF _IONBF);
@EXPORT_OK = qw(
pipe
autoflush
output_field_separator
output_record_separator
input_record_separator
input_line_number
format_page_number
format_lines_per_page
format_lines_left
format_name
format_top_name
format_line_break_characters
format_formfeed
print
printf
getline
getlines
);
#
# Everything we're willing to export, we must first import.
#
IO::Handle->import( grep { !defined(&$_) } @EXPORT, @EXPORT_OK );
#
# Some people call "FileHandle::function", so all the functions
# that were in the old FileHandle class must be imported, too.
#
{
no strict 'refs';
my %import = (
'IO::Handle' =>
[qw(DESTROY new_from_fd fdopen close fileno getc ungetc gets
eof flush error clearerr setbuf setvbuf _open_mode_string)],
'IO::Seekable' =>
[qw(seek tell getpos setpos)],
'IO::File' =>
[qw(new new_tmpfile open)]
);
for my $pkg (keys %import) {
for my $func (@{$import{$pkg}}) {
my $c = *{"${pkg}::$func"}{CODE}
or die "${pkg}::$func missing";
*$func = $c;
}
}
}
#
# Specialized importer for Fcntl magic.
#
sub import {
my $pkg = shift;
my $callpkg = caller;
require Exporter;
Exporter::export($pkg, $callpkg, @_);
#
# If the Fcntl extension is available,
# export its constants.
#
eval {
require Fcntl;
Exporter::export('Fcntl', $callpkg);
};
}
################################################
# This is the only exported function we define;
# the rest come from other classes.
#
sub pipe {
my $r = IO::Handle->new;
my $w = IO::Handle->new;
CORE::pipe($r, $w) or return undef;
($r, $w);
}
# Rebless standard file handles
bless *STDIN{IO}, "FileHandle" if ref *STDIN{IO} eq "IO::Handle";
bless *STDOUT{IO}, "FileHandle" if ref *STDOUT{IO} eq "IO::Handle";
bless *STDERR{IO}, "FileHandle" if ref *STDERR{IO} eq "IO::Handle";
1;
__END__
=head1 NAME
FileHandle - supply object methods for filehandles
=head1 SYNOPSIS
use FileHandle;
my $fh = FileHandle->new;
if ($fh->open("< file")) {
print <$fh>;
$fh->close;
}
my $fh = FileHandle->new("> FOO");
if (defined $fh) {
print $fh "bar\n";
$fh->close;
}
my $fh = FileHandle->new("file", "r");
if (defined $fh) {
print <$fh>;
undef $fh; # automatically closes the file
}
my $fh = FileHandle->new("file", O_WRONLY|O_APPEND);
if (defined $fh) {
print $fh "corge\n";
undef $fh; # automatically closes the file
}
my $pos = $fh->getpos;
$fh->setpos($pos);
$fh->setvbuf(my $buffer_var, _IOLBF, 1024);
my ($readfh, $writefh) = FileHandle::pipe;
autoflush STDOUT 1;
=head1 DESCRIPTION
NOTE: This class is now a front-end to the IO::* classes.
C<FileHandle::new> creates a C<FileHandle>, which is a reference to a
newly created symbol (see the L<Symbol> package). If it receives any
parameters, they are passed to C<FileHandle::open>; if the open fails,
the C<FileHandle> object is destroyed. Otherwise, it is returned to
the caller.
C<FileHandle::new_from_fd> creates a C<FileHandle> like C<new> does.
It requires two parameters, which are passed to C<FileHandle::fdopen>;
if the fdopen fails, the C<FileHandle> object is destroyed.
Otherwise, it is returned to the caller.
C<FileHandle::open> accepts one parameter or two. With one parameter,
it is just a front end for the built-in C<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 C<FileHandle::open> receives a Perl mode string (">", "+<", etc.)
or a POSIX fopen() mode string ("w", "r+", etc.), it uses the basic
Perl C<open> operator.
If C<FileHandle::open> is given a numeric mode, it passes that mode
and the optional permissions value to the Perl C<sysopen> operator.
For convenience, C<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.
C<FileHandle::fdopen> is like C<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
C<FileHandle::getpos> returns an opaque value that represents the
current position of the FileHandle, and C<FileHandle::setpos> uses
that value to return to a previously visited position.
If the C function setvbuf() is available, then C<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 C<_IOFBF>, C<_IOLBF>, and C<_IONBF>, except that the buffer
parameter specifies a scalar variable to use as a buffer. WARNING: A
variable used as a buffer by C<FileHandle::setvbuf> must not be
modified in any way until the FileHandle is closed or until
C<FileHandle::setvbuf> is called again, or memory corruption may
result!
See L<perlfunc> for complete descriptions of each of the following
supported C<FileHandle> methods, which are just front ends for the
corresponding built-in functions:
close
fileno
getc
gets
eof
clearerr
seek
tell
See L<perlvar> for complete descriptions of each of the following
supported C<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:
=over 4
=item $fh->print
See L<perlfunc/print>.
=item $fh->printf
See L<perlfunc/printf>.
=item $fh->getline
This works like <$fh> described in L<perlop/"I/O Operators">
except that it's more readable and can be safely called in a
list context but still returns just one line.
=item $fh->getlines
This works like <$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.
=back
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.
=head1 SEE ALSO
The B<IO> extension,
L<perlfunc>,
L<perlop/"I/O Operators">.
=cut
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