xref: /openbsd-src/gnu/usr.bin/perl/lib/Benchmark.t (revision d13be5d47e4149db2549a9828e244d59dbc43f15)
1#!./perl -w
2
3BEGIN {
4    chdir 't' if -d 't';
5    @INC = ('../lib');
6}
7
8use warnings;
9use strict;
10use vars qw($foo $bar $baz $ballast);
11use Test::More tests => 194;
12
13use Benchmark qw(:all);
14
15my $delta = 0.4;
16
17# Some timing ballast
18sub fib {
19  my $n = shift;
20  return $n if $n < 2;
21  fib($n-1) + fib($n-2);
22}
23$ballast = 15;
24
25my $All_Pattern =
26    qr/(\d+) +wallclock secs? +\( *(-?\d+\.\d\d) +usr +(-?\d+\.\d\d) +sys +\+ +(-?\d+\.\d\d) +cusr +(-?\d+\.\d\d) +csys += +(-?\d+\.\d\d) +CPU\)/;
27my $Noc_Pattern =
28    qr/(\d+) +wallclock secs? +\( *(-?\d+\.\d\d) +usr +\+ +(-?\d+\.\d\d) +sys += +(-?\d+\.\d\d) +CPU\)/;
29my $Nop_Pattern =
30    qr/(\d+) +wallclock secs? +\( *(-?\d+\.\d\d) +cusr +\+ +(-?\d+\.\d\d) +csys += +\d+\.\d\d +CPU\)/;
31# Please don't trust the matching parenthises to be useful in this :-)
32my $Default_Pattern = qr/$All_Pattern|$Noc_Pattern/;
33
34my $t0 = new Benchmark;
35isa_ok ($t0, 'Benchmark', "Ensure we can create a benchmark object");
36
37# We use the benchmark object once we've done some work:
38
39isa_ok(timeit(5, sub {++$foo}), 'Benchmark', "timeit CODEREF");
40is ($foo, 5, "benchmarked code was run 5 times");
41
42isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
43is ($bar, 5, "benchmarked code was run 5 times");
44
45# is coderef called with spurious arguments?
46timeit( 1, sub { $foo = @_ });
47is ($foo, 0, "benchmarked code called without arguments");
48
49
50print "# Burning CPU to benchmark things will take time...\n";
51
52
53
54# We need to do something fairly slow in the coderef.
55# Same coderef. Same place in memory.
56my $coderef = sub {$baz += fib($ballast)};
57
58# The default is three.
59$baz = 0;
60my $threesecs = countit(0, $coderef);
61isa_ok($threesecs, 'Benchmark', "countit 0, CODEREF");
62isnt ($baz, 0, "benchmarked code was run");
63my $in_threesecs = $threesecs->iters;
64print "# $in_threesecs iterations\n";
65ok ($in_threesecs > 0, "iters returned positive iterations");
66
67my $estimate = int (100 * $in_threesecs / 3) / 100;
68print "# from the 3 second run estimate $estimate iterations in 1 second...\n";
69$baz = 0;
70my $onesec = countit(1, $coderef);
71isa_ok($onesec, 'Benchmark', "countit 1, CODEREF");
72isnt ($baz, 0, "benchmarked code was run");
73my $in_onesec = $onesec->iters;
74print "# $in_onesec iterations\n";
75ok ($in_onesec > 0, "iters returned positive iterations");
76
77{
78  my $difference = $in_onesec - $estimate;
79  my $actual = abs ($difference / $in_onesec);
80  cmp_ok($actual, '<=', $delta, "is $in_onesec within $delta of estimate ($estimate)")
81    or diag("# $in_onesec is between " . ($delta / 2) . " and $delta of estimate. Not that safe.");
82}
83
84# I found that the eval'ed version was 3 times faster than the coderef.
85# (now it has a different ballast value)
86$baz = 0;
87my $again = countit(1, '$baz += fib($ballast)');
88isa_ok($onesec, 'Benchmark', "countit 1, eval");
89isnt ($baz, 0, "benchmarked code was run");
90my $in_again = $again->iters;
91print "# $in_again iterations\n";
92ok ($in_again > 0, "iters returned positive iterations");
93
94
95my $t1 = new Benchmark;
96isa_ok ($t1, 'Benchmark', "Create another benchmark object now we're finished");
97
98my $diff = timediff ($t1, $t0);
99isa_ok ($diff, 'Benchmark', "Get the time difference");
100isa_ok (timesum ($t0, $t1), 'Benchmark', "check timesum");
101
102my $default = timestr ($diff);
103isnt ($default, '', 'timestr ($diff)');
104my $auto = timestr ($diff, 'auto');
105is ($auto, $default, 'timestr ($diff, "auto") matches timestr ($diff)');
106
107{
108    my $all = timestr ($diff, 'all');
109    like ($all, $All_Pattern, 'timestr ($diff, "all")');
110    print "# $all\n";
111
112    my ($wallclock, $usr, $sys, $cusr, $csys, $cpu) = $all =~ $All_Pattern;
113
114    is (timestr ($diff, 'none'), '', "none supresses output");
115
116    my $noc = timestr ($diff, 'noc');
117    like ($noc, qr/$wallclock +wallclock secs? +\( *$usr +usr +\+ +$sys +sys += +$cpu +CPU\)/, 'timestr ($diff, "noc")');
118
119    my $nop = timestr ($diff, 'nop');
120    like ($nop, qr/$wallclock +wallclock secs? +\( *$cusr +cusr +\+ +$csys +csys += +\d+\.\d\d +CPU\)/, 'timestr ($diff, "nop")');
121
122    if ($auto eq $noc) {
123        pass ('"auto" is "noc"');
124    } else {
125        is ($auto, $all, '"auto" isn\'t "noc", so should be eq to "all"');
126    }
127
128    like (timestr ($diff, 'all', 'E'),
129          qr/(\d+) +wallclock secs? +\( *\d\.\d+E[-+]?\d\d\d? +usr +\d\.\d+E[-+]?\d\d\d? +sys +\+ +\d\.\d+E[-+]?\d\d\d? +cusr +\d\.\d+E[-+]?\d\d\d? +csys += +\d\.\d+E[-+]?\d\d\d? +CPU\)/, 'timestr ($diff, "all", "E") [sprintf format of "E"]');
130}
131
132my $out = tie *OUT, 'TieOut';
133
134my $iterations = 3;
135
136$foo = 0;
137select(OUT);
138my $got = timethis($iterations, sub {++$foo});
139select(STDOUT);
140isa_ok($got, 'Benchmark', "timethis CODEREF");
141is ($foo, $iterations, "benchmarked code was run $iterations times");
142
143$got = $out->read();
144like ($got, qr/^timethis $iterations/, 'default title');
145like ($got, $Default_Pattern, 'default format is all or noc');
146
147$bar = 0;
148select(OUT);
149$got = timethis($iterations, '++$bar');
150select(STDOUT);
151isa_ok($got, 'Benchmark', "timethis eval");
152is ($bar, $iterations, "benchmarked code was run $iterations times");
153
154$got = $out->read();
155like ($got, qr/^timethis $iterations/, 'default title');
156like ($got, $Default_Pattern, 'default format is all or noc');
157
158my $title = 'lies, damn lies and benchmarks';
159$foo = 0;
160select(OUT);
161$got = timethis($iterations, sub {++$foo}, $title);
162select(STDOUT);
163isa_ok($got, 'Benchmark', "timethis with title");
164is ($foo, $iterations, "benchmarked code was run $iterations times");
165
166$got = $out->read();
167like ($got, qr/^$title:/, 'specify title');
168like ($got, $Default_Pattern, 'default format is all or noc');
169
170# default is auto, which is all or noc. nop can never match the default
171$foo = 0;
172select(OUT);
173$got = timethis($iterations, sub {++$foo}, $title, 'nop');
174select(STDOUT);
175isa_ok($got, 'Benchmark', "timethis with format");
176is ($foo, $iterations, "benchmarked code was run $iterations times");
177
178$got = $out->read();
179like ($got, qr/^$title:/, 'specify title');
180like ($got, $Nop_Pattern, 'specify format as nop');
181
182{
183    $foo = 0;
184    select(OUT);
185    my $start = time;
186    $got = timethis(-2, sub {$foo+= fib($ballast)}, $title, 'none');
187    my $end = time;
188    select(STDOUT);
189    isa_ok($got, 'Benchmark',
190           "timethis, at least 2 seconds with format 'none'");
191    ok ($foo > 0, "benchmarked code was run");
192    ok ($end - $start > 1, "benchmarked code ran for over 1 second");
193
194    $got = $out->read();
195    # Remove any warnings about having too few iterations.
196    $got =~ s/\(warning:[^\)]+\)//gs;
197    $got =~ s/^[ \t\n]+//s; # Remove all the whitespace from the beginning
198
199    is ($got, '', "format 'none' should suppress output");
200}
201
202$foo = $bar = $baz = 0;
203select(OUT);
204$got = timethese($iterations, { Foo => sub {++$foo}, Bar => '++$bar',
205                                Baz => sub {++$baz} });
206select(STDOUT);
207is(ref ($got), 'HASH', "timethese should return a hashref");
208isa_ok($got->{Foo}, 'Benchmark', "Foo value");
209isa_ok($got->{Bar}, 'Benchmark', "Bar value");
210isa_ok($got->{Baz}, 'Benchmark', "Baz value");
211eq_set([keys %$got], [qw(Foo Bar Baz)], 'should be exactly three objects');
212is ($foo, $iterations, "Foo code was run $iterations times");
213is ($bar, $iterations, "Bar code was run $iterations times");
214is ($baz, $iterations, "Baz code was run $iterations times");
215
216$got = $out->read();
217# Remove any warnings about having too few iterations.
218$got =~ s/\(warning:[^\)]+\)//gs;
219
220like ($got, qr/timing $iterations iterations of\s+Bar\W+Baz\W+Foo\W*?\.\.\./s,
221      'check title');
222# Remove the title
223$got =~ s/.*\.\.\.//s;
224like ($got, qr/\bBar\b.*\bBaz\b.*\bFoo\b/s, 'check output is in sorted order');
225like ($got, $Default_Pattern, 'should find default format somewhere');
226
227
228{ # ensure 'use strict' does not leak from Benchmark.pm into benchmarked code
229    no strict;
230    select OUT;
231
232    eval {
233        timethese( 1,
234                   { undeclared_var => q{ $i++; $i-- },
235                     symbolic_ref   => q{ $bar = 42;
236                                          $foo = 'bar';
237                                          $q = ${$foo} },
238                   },
239                   'none'
240                  );
241
242    };
243    is( $@, '', q{no strict leakage in name => 'code'} );
244
245    eval {
246        timethese( 1,
247                   { undeclared_var => sub { $i++; $i-- },
248                     symbolic_ref   => sub { $bar = 42;
249                                             $foo = 'bar';
250                                             return ${$foo} },
251                   },
252                   'none'
253                 );
254    };
255    is( $@, '', q{no strict leakage in name => sub { code }} );
256
257    # clear out buffer
258    $out->read;
259}
260
261
262my $code_to_test =  { Foo => sub {$foo+=fib($ballast-2)},
263                      Bar => sub {$bar+=fib($ballast)}};
264# Keep these for later.
265my $results;
266{
267    $foo = $bar = 0;
268    select(OUT);
269    my $start = times;
270    $results = timethese(-0.1, $code_to_test, 'none');
271    my $end = times;
272    select(STDOUT);
273
274    is(ref ($results), 'HASH', "timethese should return a hashref");
275    isa_ok($results->{Foo}, 'Benchmark', "Foo value");
276    isa_ok($results->{Bar}, 'Benchmark', "Bar value");
277    eq_set([keys %$results], [qw(Foo Bar)], 'should be exactly two objects');
278    ok ($foo > 0, "Foo code was run");
279    ok ($bar > 0, "Bar code was run");
280
281    ok (($end - $start) > 0.1, "benchmarked code ran for over 0.1 seconds");
282
283    $got = $out->read();
284    # Remove any warnings about having too few iterations.
285    $got =~ s/\(warning:[^\)]+\)//gs;
286    is ($got =~ tr/ \t\n//c, 0, "format 'none' should suppress output");
287}
288my $graph_dissassembly =
289    qr!^[ \t]+(\S+)[ \t]+(\w+)[ \t]+(\w+)[ \t]*		# Title line
290    \n[ \t]*(\w+)[ \t]+([0-9.]+(?:/s)?)[ \t]+(-+)[ \t]+(-?\d+%)[ \t]*
291    \n[ \t]*(\w+)[ \t]+([0-9.]+(?:/s)?)[ \t]+(-?\d+%)[ \t]+(-+)[ \t]*$!xm;
292
293sub check_graph_consistency {
294    my (	$ratetext, $slowc, $fastc,
295        $slowr, $slowratet, $slowslow, $slowfastt,
296        $fastr, $fastratet, $fastslowt, $fastfast)
297        = @_;
298    my $all_passed = 1;
299    $all_passed
300      &= is ($slowc, $slowr, "left col tag should be top row tag");
301    $all_passed
302      &= is ($fastc, $fastr, "right col tag should be bottom row tag");
303    $all_passed &=
304      like ($slowslow, qr/^-+/, "should be dash for comparing slow with slow");
305    $all_passed
306      &= is ($slowslow, $fastfast, "slow v slow should be same as fast v fast");
307    my $slowrate = $slowratet;
308    my $fastrate = $fastratet;
309    my ($slow_is_rate, $fast_is_rate);
310    unless ($slow_is_rate = $slowrate =~ s!/s!!) {
311        # Slow is expressed as iters per second.
312        $slowrate = 1/$slowrate if $slowrate;
313    }
314    unless ($fast_is_rate = $fastrate =~ s!/s!!) {
315        # Fast is expressed as iters per second.
316        $fastrate = 1/$fastrate if $fastrate;
317    }
318    if ($ratetext =~ /rate/i) {
319        $all_passed
320          &= ok ($slow_is_rate, "slow should be expressed as a rate");
321        $all_passed
322          &= ok ($fast_is_rate, "fast should be expressed as a rate");
323    } else {
324        $all_passed &=
325          ok (!$slow_is_rate, "slow should be expressed as a iters per second");
326        $all_passed &=
327          ok (!$fast_is_rate, "fast should be expressed as a iters per second");
328    }
329
330    (my $slowfast = $slowfastt) =~ s!%!!;
331    (my $fastslow = $fastslowt) =~ s!%!!;
332    if ($slowrate < $fastrate) {
333        pass ("slow rate is less than fast rate");
334        unless (ok ($slowfast <= 0 && $slowfast >= -100,
335                    "slowfast should be less than or equal to zero, and >= -100")) {
336          print STDERR "# slowfast $slowfast\n";
337          $all_passed = 0;
338        }
339        unless (ok ($fastslow > 0, "fastslow should be > 0")) {
340          print STDERR "# fastslow $fastslow\n";
341          $all_passed = 0;
342        }
343    } else {
344        $all_passed
345          &= is ($slowrate, $fastrate,
346                 "slow rate isn't less than fast rate, so should be the same");
347	# In OpenBSD the $slowfast is sometimes a really, really, really
348	# small number less than zero, and this gets stringified as -0.
349        $all_passed
350          &= like ($slowfast, qr/^-?0$/, "slowfast should be zero");
351        $all_passed
352          &= like ($fastslow, qr/^-?0$/, "fastslow should be zero");
353    }
354    return $all_passed;
355}
356
357sub check_graph_vs_output {
358    my ($chart, $got) = @_;
359    my (	$ratetext, $slowc, $fastc,
360        $slowr, $slowratet, $slowslow, $slowfastt,
361        $fastr, $fastratet, $fastslowt, $fastfast)
362        = $got =~ $graph_dissassembly;
363    my $all_passed
364      = check_graph_consistency (        $ratetext, $slowc, $fastc,
365                                 $slowr, $slowratet, $slowslow, $slowfastt,
366                                 $fastr, $fastratet, $fastslowt, $fastfast);
367    $all_passed
368      &= is_deeply ($chart, [['', $ratetext, $slowc, $fastc],
369                             [$slowr, $slowratet, $slowslow, $slowfastt],
370                             [$fastr, $fastratet, $fastslowt, $fastfast]],
371                    "check the chart layout matches the formatted output");
372    unless ($all_passed) {
373      print STDERR "# Something went wrong there. I got this chart:\n";
374      print STDERR "# $_\n" foreach split /\n/, $got;
375    }
376}
377
378sub check_graph {
379    my ($title, $row1, $row2) = @_;
380    is (scalar @$title, 4, "Four entries in title row");
381    is (scalar @$row1, 4, "Four entries in first row");
382    is (scalar @$row2, 4, "Four entries in second row");
383    is (shift @$title, '', "First entry of output graph should be ''");
384    check_graph_consistency (@$title, @$row1, @$row2);
385}
386
387{
388    select(OUT);
389    my $start = times;
390    my $chart = cmpthese( -0.1, { a => "++\$i", b => "\$i = sqrt(\$i++)" }, "auto" ) ;
391    my $end = times;
392    select(STDOUT);
393    ok (($end - $start) > 0.05, "benchmarked code ran for over 0.05 seconds");
394
395    $got = $out->read();
396    # Remove any warnings about having too few iterations.
397    $got =~ s/\(warning:[^\)]+\)//gs;
398
399    like ($got, qr/running\W+a\W+b.*?for at least 0\.1 CPU second/s,
400          'check title');
401    # Remove the title
402    $got =~ s/.*\.\.\.//s;
403    like ($got, $Default_Pattern, 'should find default format somewhere');
404    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
405    check_graph_vs_output ($chart, $got);
406}
407
408# Not giving auto should suppress timethese results.
409{
410    select(OUT);
411    my $start = times;
412    my $chart = cmpthese( -0.1, { a => "++\$i", b => "\$i = sqrt(\$i++)" } ) ;
413    my $end = times;
414    select(STDOUT);
415    ok (($end - $start) > 0.05, "benchmarked code ran for over 0.05 seconds");
416
417    $got = $out->read();
418    # Remove any warnings about having too few iterations.
419    $got =~ s/\(warning:[^\)]+\)//gs;
420
421    unlike ($got, qr/running\W+a\W+b.*?for at least 0\.1 CPU second/s,
422          'should not have title');
423    # Remove the title
424    $got =~ s/.*\.\.\.//s;
425    unlike ($got, $Default_Pattern, 'should not find default format somewhere');
426    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
427    check_graph_vs_output ($chart, $got);
428}
429
430{
431    $foo = $bar = 0;
432    select(OUT);
433    my $chart = cmpthese( 10, $code_to_test, 'nop' ) ;
434    select(STDOUT);
435    ok ($foo > 0, "Foo code was run");
436    ok ($bar > 0, "Bar code was run");
437
438    $got = $out->read();
439    # Remove any warnings about having too few iterations.
440    $got =~ s/\(warning:[^\)]+\)//gs;
441    like ($got, qr/timing 10 iterations of\s+Bar\W+Foo\W*?\.\.\./s,
442      'check title');
443    # Remove the title
444    $got =~ s/.*\.\.\.//s;
445    like ($got, $Nop_Pattern, 'specify format as nop');
446    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
447    check_graph_vs_output ($chart, $got);
448}
449
450{
451    $foo = $bar = 0;
452    select(OUT);
453    my $chart = cmpthese( 10, $code_to_test, 'none' ) ;
454    select(STDOUT);
455    ok ($foo > 0, "Foo code was run");
456    ok ($bar > 0, "Bar code was run");
457
458    $got = $out->read();
459    # Remove any warnings about having too few iterations.
460    $got =~ s/\(warning:[^\)]+\)//gs;
461    $got =~ s/^[ \t\n]+//s; # Remove all the whitespace from the beginning
462    is ($got, '', "format 'none' should suppress output");
463    is (ref $chart, 'ARRAY', "output should be an array ref");
464    # Some of these will go bang if the preceding test fails. There will be
465    # a big clue as to why, from the previous test's diagnostic
466    is (ref $chart->[0], 'ARRAY', "output should be an array of arrays");
467    check_graph (@$chart);
468}
469
470{
471    $foo = $bar = 0;
472    select(OUT);
473    my $chart = cmpthese( $results ) ;
474    select(STDOUT);
475    is ($foo, 0, "Foo code was not run");
476    is ($bar, 0, "Bar code was not run");
477
478    $got = $out->read();
479    ok ($got !~ /\.\.\./s, 'check that there is no title');
480    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
481    check_graph_vs_output ($chart, $got);
482}
483
484{
485    $foo = $bar = 0;
486    select(OUT);
487    my $chart = cmpthese( $results, 'none' ) ;
488    select(STDOUT);
489    is ($foo, 0, "Foo code was not run");
490    is ($bar, 0, "Bar code was not run");
491
492    $got = $out->read();
493    is ($got, '', "'none' should suppress all output");
494    is (ref $chart, 'ARRAY', "output should be an array ref");
495    # Some of these will go bang if the preceding test fails. There will be
496    # a big clue as to why, from the previous test's diagnostic
497    is (ref $chart->[0], 'ARRAY', "output should be an array of arrays");
498    check_graph (@$chart);
499}
500
501###}my $out = tie *OUT, 'TieOut'; my ($got); ###
502
503my $debug = tie *STDERR, 'TieOut';
504
505$bar = 0;
506isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
507is ($bar, 5, "benchmarked code was run 5 times");
508is ($debug->read(), '', "There was no debug output");
509
510Benchmark->debug(1);
511
512$bar = 0;
513select(OUT);
514$got = timeit(5, '++$bar');
515select(STDOUT);
516isa_ok($got, 'Benchmark', "timeit eval");
517is ($bar, 5, "benchmarked code was run 5 times");
518is ($out->read(), '', "There was no STDOUT output with debug enabled");
519isnt ($debug->read(), '', "There was STDERR debug output with debug enabled");
520
521Benchmark->debug(0);
522
523$bar = 0;
524isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
525is ($bar, 5, "benchmarked code was run 5 times");
526is ($debug->read(), '', "There was no debug output debug disabled");
527
528undef $debug;
529untie *STDERR;
530
531# To check the cache we are poking where we don't belong, inside the namespace.
532# The way benchmark is written We can't actually check whehter the cache is
533# being used, merely what's become cached.
534
535clearallcache();
536my @before_keys = keys %Benchmark::Cache;
537$bar = 0;
538isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
539is ($bar, 5, "benchmarked code was run 5 times");
540my @after5_keys = keys %Benchmark::Cache;
541$bar = 0;
542isa_ok(timeit(10, '++$bar'), 'Benchmark', "timeit eval");
543is ($bar, 10, "benchmarked code was run 10 times");
544ok (!eq_array ([keys %Benchmark::Cache], \@after5_keys), "10 differs from 5");
545
546clearcache(10);
547# Hash key order will be the same if there are the same keys.
548is_deeply ([keys %Benchmark::Cache], \@after5_keys,
549           "cleared 10, only cached results for 5 should remain");
550
551clearallcache();
552is_deeply ([keys %Benchmark::Cache], \@before_keys,
553           "back to square 1 when we clear the cache again?");
554
555
556{   # Check usage error messages
557    my %usage = %Benchmark::_Usage;
558    delete $usage{runloop};  # not public, not worrying about it just now
559
560    my @takes_no_args = qw(clearallcache disablecache enablecache);
561
562    my %cmpthese = ('forgot {}' => 'cmpthese( 42, foo => sub { 1 } )',
563                     'not result' => 'cmpthese(42)',
564                     'array ref'  => 'cmpthese( 42, [ foo => sub { 1 } ] )',
565                    );
566    while( my($name, $code) = each %cmpthese ) {
567        eval $code;
568        is( $@, $usage{cmpthese}, "cmpthese usage: $name" );
569    }
570
571    my %timethese = ('forgot {}'  => 'timethese( 42, foo => sub { 1 } )',
572                       'no code'    => 'timethese(42)',
573                       'array ref'  => 'timethese( 42, [ foo => sub { 1 } ] )',
574                      );
575
576    while( my($name, $code) = each %timethese ) {
577        eval $code;
578        is( $@, $usage{timethese}, "timethese usage: $name" );
579    }
580
581
582    while( my($func, $usage) = each %usage ) {
583        next if grep $func eq $_, @takes_no_args;
584        eval "$func()";
585        is( $@, $usage, "$func usage: no args" );
586    }
587
588    foreach my $func (@takes_no_args) {
589        eval "$func(42)";
590        is( $@, $usage{$func}, "$func usage: with args" );
591    }
592}
593
594
595package TieOut;
596
597sub TIEHANDLE {
598    my $class = shift;
599    bless(\( my $ref = ''), $class);
600}
601
602sub PRINT {
603    my $self = shift;
604    $$self .= join('', @_);
605}
606
607sub PRINTF {
608    my $self = shift;
609    $$self .= sprintf shift, @_;
610}
611
612sub read {
613    my $self = shift;
614    return substr($$self, 0, length($$self), '');
615}
616