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[perl5.git] / ext / IO / lib / IO / Handle.pm
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774d564b 1
8add82fc
PP
2package IO::Handle;
3
4=head1 NAME
5
27d4819a 6IO::Handle - supply object methods for I/O handles
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7
8=head1 SYNOPSIS
9
10 use IO::Handle;
11
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12 $io = new IO::Handle;
13 if ($io->fdopen(fileno(STDIN),"r")) {
14 print $io->getline;
15 $io->close;
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16 }
17
cf7fe8a2
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18 $io = new IO::Handle;
19 if ($io->fdopen(fileno(STDOUT),"w")) {
20 $io->print("Some text\n");
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21 }
22
3370baa8 23 use IO::Handle '_IOLBF';
cf7fe8a2 24 $io->setvbuf($buffer_var, _IOLBF, 1024);
8add82fc 25
cf7fe8a2 26 undef $io; # automatically closes the file if it's open
774d564b 27
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PP
28 autoflush STDOUT 1;
29
30=head1 DESCRIPTION
31
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PP
32C<IO::Handle> is the base class for all other IO handle classes. It is
33not intended that objects of C<IO::Handle> would be created directly,
34but instead C<IO::Handle> is inherited from by several other classes
35in the IO hierarchy.
36
37If you are reading this documentation, looking for a replacement for
38the C<FileHandle> package, then I suggest you read the documentation
cf7fe8a2 39for C<IO::File> too.
8add82fc 40
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JM
41=head1 CONSTRUCTOR
42
43=over 4
44
45=item new ()
8add82fc 46
27d4819a 47Creates a new C<IO::Handle> object.
8add82fc 48
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JM
49=item new_from_fd ( FD, MODE )
50
51Creates a C<IO::Handle> like C<new> does.
52It requires two parameters, which are passed to the method C<fdopen>;
53if the fdopen fails, the object is destroyed. Otherwise, it is returned
54to the caller.
55
56=back
57
58=head1 METHODS
8add82fc 59
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PP
60See L<perlfunc> for complete descriptions of each of the following
61supported C<IO::Handle> methods, which are just front ends for the
62corresponding built-in functions:
a6006777 63
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64 $io->close
65 $io->eof
66 $io->fileno
67 $io->format_write( [FORMAT_NAME] )
68 $io->getc
69 $io->read ( BUF, LEN, [OFFSET] )
70 $io->print ( ARGS )
71 $io->printf ( FMT, [ARGS] )
72 $io->stat
73 $io->sysread ( BUF, LEN, [OFFSET] )
2ecf2f18 74 $io->syswrite ( BUF, [LEN, [OFFSET]] )
cf7fe8a2 75 $io->truncate ( LEN )
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76
77See L<perlvar> for complete descriptions of each of the following
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78supported C<IO::Handle> methods. All of them return the previous
79value of the attribute and takes an optional single argument that when
80given will set the value. If no argument is given the previous value
81is unchanged (except for $io->autoflush will actually turn ON
82autoflush by default).
8add82fc 83
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84 $io->autoflush ( [BOOL] ) $|
85 $io->format_page_number( [NUM] ) $%
86 $io->format_lines_per_page( [NUM] ) $=
87 $io->format_lines_left( [NUM] ) $-
88 $io->format_name( [STR] ) $~
89 $io->format_top_name( [STR] ) $^
90 $io->input_line_number( [NUM]) $.
91
92The following methods are not supported on a per-filehandle basis.
93
94 IO::Handle->format_line_break_characters( [STR] ) $:
95 IO::Handle->format_formfeed( [STR]) $^L
96 IO::Handle->output_field_separator( [STR] ) $,
97 IO::Handle->output_record_separator( [STR] ) $\
98
99 IO::Handle->input_record_separator( [STR] ) $/
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100
101Furthermore, for doing normal I/O you might need these:
102
bbc7dcd2 103=over 4
8add82fc 104
cf7fe8a2 105=item $io->fdopen ( FD, MODE )
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106
107C<fdopen> is like an ordinary C<open> except that its first parameter
108is not a filename but rather a file handle name, a IO::Handle object,
109or a file descriptor number.
110
cf7fe8a2 111=item $io->opened
948ecc40 112
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113Returns true if the object is currently a valid file descriptor, false
114otherwise.
948ecc40 115
cf7fe8a2 116=item $io->getline
8add82fc 117
cf7fe8a2 118This works like <$io> described in L<perlop/"I/O Operators">
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119except that it's more readable and can be safely called in a
120list context but still returns just one line.
8add82fc 121
cf7fe8a2 122=item $io->getlines
8add82fc 123
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124This works like <$io> when called in a list context to read all
125the remaining lines in a file, except that it's more readable.
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126It will also croak() if accidentally called in a scalar context.
127
cf7fe8a2 128=item $io->ungetc ( ORD )
27d4819a 129
948ecc40 130Pushes a character with the given ordinal value back onto the given
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131handle's input stream. Only one character of pushback per handle is
132guaranteed.
27d4819a 133
cf7fe8a2 134=item $io->write ( BUF, LEN [, OFFSET ] )
27d4819a 135
948ecc40 136This C<write> is like C<write> found in C, that is it is the
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JM
137opposite of read. The wrapper for the perl C<write> function is
138called C<format_write>.
139
cf7fe8a2 140=item $io->error
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CS
141
142Returns a true value if the given handle has experienced any errors
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NC
143since it was opened or since the last call to C<clearerr>, or if the
144handle is invalid. It only returns false for a valid handle with no
145outstanding errors.
948ecc40 146
cf7fe8a2 147=item $io->clearerr
948ecc40 148
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149Clear the given handle's error indicator. Returns -1 if the handle is
150invalid, 0 otherwise.
27d4819a 151
cf7fe8a2
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152=item $io->sync
153
154C<sync> synchronizes a file's in-memory state with that on the
155physical medium. C<sync> does not operate at the perlio api level, but
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156operates on the file descriptor (similar to sysread, sysseek and
157systell). This means that any data held at the perlio api level will not
158be synchronized. To synchronize data that is buffered at the perlio api
159level you must use the flush method. C<sync> is not implemented on all
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160platforms. Returns "0 but true" on success, C<undef> on error, C<undef>
161for an invalid handle. See L<fsync(3c)>.
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162
163=item $io->flush
164
165C<flush> causes perl to flush any buffered data at the perlio api level.
166Any unread data in the buffer will be discarded, and any unwritten data
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167will be written to the underlying file descriptor. Returns "0 but true"
168on success, C<undef> on error.
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169
170=item $io->printflush ( ARGS )
171
172Turns on autoflush, print ARGS and then restores the autoflush status of the
a47f745f 173C<IO::Handle> object. Returns the return value from print.
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174
175=item $io->blocking ( [ BOOL ] )
176
177If called with an argument C<blocking> will turn on non-blocking IO if
178C<BOOL> is false, and turn it off if C<BOOL> is true.
179
180C<blocking> will return the value of the previous setting, or the
181current setting if C<BOOL> is not given.
182
183If an error occurs C<blocking> will return undef and C<$!> will be set.
184
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185=back
186
cf7fe8a2 187
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188If the C functions setbuf() and/or setvbuf() are available, then
189C<IO::Handle::setbuf> and C<IO::Handle::setvbuf> set the buffering
190policy for an IO::Handle. The calling sequences for the Perl functions
191are the same as their C counterparts--including the constants C<_IOFBF>,
192C<_IOLBF>, and C<_IONBF> for setvbuf()--except that the buffer parameter
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193specifies a scalar variable to use as a buffer. You should only
194change the buffer before any I/O, or immediately after calling flush.
195
196WARNING: A variable used as a buffer by C<setbuf> or C<setvbuf> B<must not
197be modified> in any way until the IO::Handle is closed or C<setbuf> or
198C<setvbuf> is called again, or memory corruption may result! Remember that
199the order of global destruction is undefined, so even if your buffer
200variable remains in scope until program termination, it may be undefined
201before the file IO::Handle is closed. Note that you need to import the
202constants C<_IOFBF>, C<_IOLBF>, and C<_IONBF> explicitly. Like C, setbuf
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203returns nothing. setvbuf returns "0 but true", on success, C<undef> on
204failure.
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205
206Lastly, there is a special method for working under B<-T> and setuid/gid
207scripts:
515e7bd7 208
bbc7dcd2 209=over 4
515e7bd7 210
cf7fe8a2 211=item $io->untaint
515e7bd7
RR
212
213Marks the object as taint-clean, and as such data read from it will also
214be considered taint-clean. Note that this is a very trusting action to
215take, and appropriate consideration for the data source and potential
a47f745f
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216vulnerability should be kept in mind. Returns 0 on success, -1 if setting
217the taint-clean flag failed. (eg invalid handle)
515e7bd7
RR
218
219=back
220
27d4819a 221=head1 NOTE
8add82fc 222
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223A C<IO::Handle> object is a reference to a symbol/GLOB reference (see
224the C<Symbol> package). Some modules that
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PP
225inherit from C<IO::Handle> may want to keep object related variables
226in the hash table part of the GLOB. In an attempt to prevent modules
227trampling on each other I propose the that any such module should prefix
228its variables with its own name separated by _'s. For example the IO::Socket
229module keeps a C<timeout> variable in 'io_socket_timeout'.
230
231=head1 SEE ALSO
232
233L<perlfunc>,
234L<perlop/"I/O Operators">,
774d564b 235L<IO::File>
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236
237=head1 BUGS
238
239Due to backwards compatibility, all filehandles resemble objects
240of class C<IO::Handle>, or actually classes derived from that class.
241They actually aren't. Which means you can't derive your own
242class from C<IO::Handle> and inherit those methods.
243
244=head1 HISTORY
245
cf7fe8a2 246Derived from FileHandle.pm by Graham Barr E<lt>F<gbarr@pobox.com>E<gt>
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247
248=cut
249
14fe70c2 250require 5.6.1;
7a4c00b4 251use strict;
17f410f9 252our($VERSION, @EXPORT_OK, @ISA);
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253use Carp;
254use Symbol;
255use SelectSaver;
cf7fe8a2 256use IO (); # Load the XS module
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257
258require Exporter;
259@ISA = qw(Exporter);
260
76fbd8c4 261$VERSION = "1.21_00";
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262
263@EXPORT_OK = qw(
264 autoflush
265 output_field_separator
266 output_record_separator
267 input_record_separator
268 input_line_number
269 format_page_number
270 format_lines_per_page
271 format_lines_left
272 format_name
273 format_top_name
274 format_line_break_characters
275 format_formfeed
276 format_write
277
278 print
279 printf
280 getline
281 getlines
282
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GS
283 printflush
284 flush
285
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286 SEEK_SET
287 SEEK_CUR
288 SEEK_END
289 _IOFBF
290 _IOLBF
291 _IONBF
8add82fc
PP
292);
293
8add82fc
PP
294################################################
295## Constructors, destructors.
296##
297
298sub new {
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299 my $class = ref($_[0]) || $_[0] || "IO::Handle";
300 @_ == 1 or croak "usage: new $class";
cf7fe8a2
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301 my $io = gensym;
302 bless $io, $class;
8add82fc
PP
303}
304
305sub new_from_fd {
27d4819a
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306 my $class = ref($_[0]) || $_[0] || "IO::Handle";
307 @_ == 3 or croak "usage: new_from_fd $class FD, MODE";
cf7fe8a2 308 my $io = gensym;
c927212d 309 shift;
cf7fe8a2 310 IO::Handle::fdopen($io, @_)
8add82fc 311 or return undef;
cf7fe8a2 312 bless $io, $class;
8add82fc
PP
313}
314
98d4926f
CS
315#
316# There is no need for DESTROY to do anything, because when the
317# last reference to an IO object is gone, Perl automatically
318# closes its associated files (if any). However, to avoid any
319# attempts to autoload DESTROY, we here define it to do nothing.
320#
321sub DESTROY {}
7a4c00b4 322
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323
324################################################
325## Open and close.
326##
327
328sub _open_mode_string {
329 my ($mode) = @_;
330 $mode =~ /^\+?(<|>>?)$/
331 or $mode =~ s/^r(\+?)$/$1</
332 or $mode =~ s/^w(\+?)$/$1>/
333 or $mode =~ s/^a(\+?)$/$1>>/
334 or croak "IO::Handle: bad open mode: $mode";
335 $mode;
336}
337
338sub fdopen {
cf7fe8a2
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339 @_ == 3 or croak 'usage: $io->fdopen(FD, MODE)';
340 my ($io, $fd, $mode) = @_;
8add82fc
PP
341 local(*GLOB);
342
343 if (ref($fd) && "".$fd =~ /GLOB\(/o) {
344 # It's a glob reference; Alias it as we cannot get name of anon GLOBs
345 my $n = qualify(*GLOB);
346 *GLOB = *{*$fd};
347 $fd = $n;
348 } elsif ($fd =~ m#^\d+$#) {
349 # It's an FD number; prefix with "=".
350 $fd = "=$fd";
351 }
352
cf7fe8a2
GS
353 open($io, _open_mode_string($mode) . '&' . $fd)
354 ? $io : undef;
8add82fc
PP
355}
356
357sub close {
cf7fe8a2
GS
358 @_ == 1 or croak 'usage: $io->close()';
359 my($io) = @_;
8add82fc 360
cf7fe8a2 361 close($io);
8add82fc
PP
362}
363
364################################################
365## Normal I/O functions.
366##
367
8add82fc 368# flock
8add82fc 369# select
8add82fc
PP
370
371sub opened {
cf7fe8a2 372 @_ == 1 or croak 'usage: $io->opened()';
8add82fc
PP
373 defined fileno($_[0]);
374}
375
376sub fileno {
cf7fe8a2 377 @_ == 1 or croak 'usage: $io->fileno()';
8add82fc
PP
378 fileno($_[0]);
379}
380
381sub getc {
cf7fe8a2 382 @_ == 1 or croak 'usage: $io->getc()';
8add82fc
PP
383 getc($_[0]);
384}
385
8add82fc 386sub eof {
cf7fe8a2 387 @_ == 1 or croak 'usage: $io->eof()';
8add82fc
PP
388 eof($_[0]);
389}
390
391sub print {
cf7fe8a2 392 @_ or croak 'usage: $io->print(ARGS)';
8add82fc
PP
393 my $this = shift;
394 print $this @_;
395}
396
397sub printf {
cf7fe8a2 398 @_ >= 2 or croak 'usage: $io->printf(FMT,[ARGS])';
8add82fc
PP
399 my $this = shift;
400 printf $this @_;
401}
402
403sub getline {
cf7fe8a2 404 @_ == 1 or croak 'usage: $io->getline()';
8add82fc
PP
405 my $this = shift;
406 return scalar <$this>;
407}
408
f86702cc
PP
409*gets = \&getline; # deprecated
410
8add82fc 411sub getlines {
cf7fe8a2 412 @_ == 1 or croak 'usage: $io->getlines()';
8add82fc 413 wantarray or
cf7fe8a2 414 croak 'Can\'t call $io->getlines in a scalar context, use $io->getline';
27d4819a 415 my $this = shift;
8add82fc
PP
416 return <$this>;
417}
418
419sub truncate {
cf7fe8a2 420 @_ == 2 or croak 'usage: $io->truncate(LEN)';
8add82fc
PP
421 truncate($_[0], $_[1]);
422}
423
424sub read {
cf7fe8a2 425 @_ == 3 || @_ == 4 or croak 'usage: $io->read(BUF, LEN [, OFFSET])';
8add82fc
PP
426 read($_[0], $_[1], $_[2], $_[3] || 0);
427}
428
27d4819a 429sub sysread {
cf7fe8a2 430 @_ == 3 || @_ == 4 or croak 'usage: $io->sysread(BUF, LEN [, OFFSET])';
27d4819a
JM
431 sysread($_[0], $_[1], $_[2], $_[3] || 0);
432}
433
8add82fc 434sub write {
8fd73a68 435 @_ >= 2 && @_ <= 4 or croak 'usage: $io->write(BUF [, LEN [, OFFSET]])';
8add82fc 436 local($\) = "";
8fd73a68 437 $_[2] = length($_[1]) unless defined $_[2];
8add82fc
PP
438 print { $_[0] } substr($_[1], $_[3] || 0, $_[2]);
439}
440
27d4819a 441sub syswrite {
8fd73a68 442 @_ >= 2 && @_ <= 4 or croak 'usage: $io->syswrite(BUF [, LEN [, OFFSET]])';
2ecf2f18
GB
443 if (defined($_[2])) {
444 syswrite($_[0], $_[1], $_[2], $_[3] || 0);
445 } else {
446 syswrite($_[0], $_[1]);
447 }
27d4819a
JM
448}
449
8add82fc 450sub stat {
cf7fe8a2 451 @_ == 1 or croak 'usage: $io->stat()';
8add82fc
PP
452 stat($_[0]);
453}
454
455################################################
456## State modification functions.
457##
458
459sub autoflush {
cf7fe8a2 460 my $old = new SelectSaver qualify($_[0], caller);
8add82fc
PP
461 my $prev = $|;
462 $| = @_ > 1 ? $_[1] : 1;
463 $prev;
464}
465
466sub output_field_separator {
cf7fe8a2
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467 carp "output_field_separator is not supported on a per-handle basis"
468 if ref($_[0]);
8add82fc
PP
469 my $prev = $,;
470 $, = $_[1] if @_ > 1;
471 $prev;
472}
473
474sub output_record_separator {
cf7fe8a2
GS
475 carp "output_record_separator is not supported on a per-handle basis"
476 if ref($_[0]);
8add82fc
PP
477 my $prev = $\;
478 $\ = $_[1] if @_ > 1;
479 $prev;
480}
481
482sub input_record_separator {
cf7fe8a2
GS
483 carp "input_record_separator is not supported on a per-handle basis"
484 if ref($_[0]);
8add82fc
PP
485 my $prev = $/;
486 $/ = $_[1] if @_ > 1;
487 $prev;
488}
489
490sub input_line_number {
91cce263
PJ
491 local $.;
492 my $tell = tell qualify($_[0], caller) if ref($_[0]);
493 my $prev = $.;
494 $. = $_[1] if @_ > 1;
495 $prev;
496}
91cce263 497
8add82fc 498sub format_page_number {
b61d194c 499 my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
8add82fc
PP
500 my $prev = $%;
501 $% = $_[1] if @_ > 1;
502 $prev;
503}
504
505sub format_lines_per_page {
b61d194c 506 my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
8add82fc
PP
507 my $prev = $=;
508 $= = $_[1] if @_ > 1;
509 $prev;
510}
511
512sub format_lines_left {
b61d194c 513 my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
8add82fc
PP
514 my $prev = $-;
515 $- = $_[1] if @_ > 1;
516 $prev;
517}
518
519sub format_name {
b61d194c 520 my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
8add82fc
PP
521 my $prev = $~;
522 $~ = qualify($_[1], caller) if @_ > 1;
523 $prev;
524}
525
526sub format_top_name {
b61d194c 527 my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
8add82fc
PP
528 my $prev = $^;
529 $^ = qualify($_[1], caller) if @_ > 1;
530 $prev;
531}
532
533sub format_line_break_characters {
cf7fe8a2
GS
534 carp "format_line_break_characters is not supported on a per-handle basis"
535 if ref($_[0]);
8add82fc
PP
536 my $prev = $:;
537 $: = $_[1] if @_ > 1;
538 $prev;
539}
540
541sub format_formfeed {
cf7fe8a2
GS
542 carp "format_formfeed is not supported on a per-handle basis"
543 if ref($_[0]);
8add82fc
PP
544 my $prev = $^L;
545 $^L = $_[1] if @_ > 1;
546 $prev;
547}
548
549sub formline {
cf7fe8a2 550 my $io = shift;
8add82fc
PP
551 my $picture = shift;
552 local($^A) = $^A;
553 local($\) = "";
554 formline($picture, @_);
cf7fe8a2 555 print $io $^A;
8add82fc
PP
556}
557
558sub format_write {
cf7fe8a2 559 @_ < 3 || croak 'usage: $io->write( [FORMAT_NAME] )';
8add82fc 560 if (@_ == 2) {
cf7fe8a2
GS
561 my ($io, $fmt) = @_;
562 my $oldfmt = $io->format_name($fmt);
563 CORE::write($io);
564 $io->format_name($oldfmt);
8add82fc 565 } else {
56f7f34b 566 CORE::write($_[0]);
8add82fc
PP
567 }
568}
569
21e970cc 570# XXX undocumented
27d4819a 571sub fcntl {
cf7fe8a2 572 @_ == 3 || croak 'usage: $io->fcntl( OP, VALUE );';
21e970cc
GS
573 my ($io, $op) = @_;
574 return fcntl($io, $op, $_[2]);
27d4819a
JM
575}
576
21e970cc 577# XXX undocumented
27d4819a 578sub ioctl {
cf7fe8a2 579 @_ == 3 || croak 'usage: $io->ioctl( OP, VALUE );';
21e970cc
GS
580 my ($io, $op) = @_;
581 return ioctl($io, $op, $_[2]);
27d4819a 582}
8add82fc 583
cf7fe8a2
GS
584# this sub is for compatability with older releases of IO that used
585# a sub called constant to detemine if a constant existed -- GMB
586#
587# The SEEK_* and _IO?BF constants were the only constants at that time
588# any new code should just chech defined(&CONSTANT_NAME)
589
590sub constant {
591 no strict 'refs';
592 my $name = shift;
593 (($name =~ /^(SEEK_(SET|CUR|END)|_IO[FLN]BF)$/) && defined &{$name})
594 ? &{$name}() : undef;
595}
596
597
6facdfff 598# so that flush.pl can be deprecated
cf7fe8a2
GS
599
600sub printflush {
601 my $io = shift;
602 my $old = new SelectSaver qualify($io, caller) if ref($io);
603 local $| = 1;
604 if(ref($io)) {
605 print $io @_;
606 }
607 else {
608 print @_;
609 }
610}
611
8add82fc 6121;