xref: /openbsd-src/gnu/usr.bin/perl/lib/Benchmark.t (revision daf88648c0e349d5c02e1504293082072c981640)
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 / $in_onesec);
80  ok ($actual < $delta, "is $in_onesec within $delta of estimate ($estimate)");
81  print "# $in_onesec is between " . ($delta / 2) .
82    " and $delta of estimate. Not that safe.\n" if $actual > $delta/2;
83}
84
85# I found that the eval'ed version was 3 times faster than the coderef.
86# (now it has a different ballast value)
87$baz = 0;
88my $again = countit(1, '$baz += fib($ballast)');
89isa_ok($onesec, 'Benchmark', "countit 1, eval");
90isnt ($baz, 0, "benchmarked code was run");
91my $in_again = $again->iters;
92print "# $in_again iterations\n";
93ok ($in_again > 0, "iters returned positive iterations");
94
95
96my $t1 = new Benchmark;
97isa_ok ($t1, 'Benchmark', "Create another benchmark object now we're finished");
98
99my $diff = timediff ($t1, $t0);
100isa_ok ($diff, 'Benchmark', "Get the time difference");
101isa_ok (timesum ($t0, $t1), 'Benchmark', "check timesum");
102
103my $default = timestr ($diff);
104isnt ($default, '', 'timestr ($diff)');
105my $auto = timestr ($diff, 'auto');
106is ($auto, $default, 'timestr ($diff, "auto") matches timestr ($diff)');
107
108{
109    my $all = timestr ($diff, 'all');
110    like ($all, $All_Pattern, 'timestr ($diff, "all")');
111    print "# $all\n";
112
113    my ($wallclock, $usr, $sys, $cusr, $csys, $cpu) = $all =~ $All_Pattern;
114
115    is (timestr ($diff, 'none'), '', "none supresses output");
116
117    my $noc = timestr ($diff, 'noc');
118    like ($noc, qr/$wallclock +wallclock secs? +\( *$usr +usr +\+ +$sys +sys += +$cpu +CPU\)/, 'timestr ($diff, "noc")');
119
120    my $nop = timestr ($diff, 'nop');
121    like ($nop, qr/$wallclock +wallclock secs? +\( *$cusr +cusr +\+ +$csys +csys += +\d+\.\d\d +CPU\)/, 'timestr ($diff, "nop")');
122
123    if ($auto eq $noc) {
124        pass ('"auto" is "noc"');
125    } else {
126        is ($auto, $all, '"auto" isn\'t "noc", so should be eq to "all"');
127    }
128
129    like (timestr ($diff, 'all', 'E'),
130          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"]');
131}
132
133my $out = tie *OUT, 'TieOut';
134
135my $iterations = 3;
136
137$foo = 0;
138select(OUT);
139my $got = timethis($iterations, sub {++$foo});
140select(STDOUT);
141isa_ok($got, 'Benchmark', "timethis CODEREF");
142is ($foo, $iterations, "benchmarked code was run $iterations times");
143
144$got = $out->read();
145like ($got, qr/^timethis $iterations/, 'default title');
146like ($got, $Default_Pattern, 'default format is all or noc');
147
148$bar = 0;
149select(OUT);
150$got = timethis($iterations, '++$bar');
151select(STDOUT);
152isa_ok($got, 'Benchmark', "timethis eval");
153is ($bar, $iterations, "benchmarked code was run $iterations times");
154
155$got = $out->read();
156like ($got, qr/^timethis $iterations/, 'default title');
157like ($got, $Default_Pattern, 'default format is all or noc');
158
159my $title = 'lies, damn lies and benchmarks';
160$foo = 0;
161select(OUT);
162$got = timethis($iterations, sub {++$foo}, $title);
163select(STDOUT);
164isa_ok($got, 'Benchmark', "timethis with title");
165is ($foo, $iterations, "benchmarked code was run $iterations times");
166
167$got = $out->read();
168like ($got, qr/^$title:/, 'specify title');
169like ($got, $Default_Pattern, 'default format is all or noc');
170
171# default is auto, which is all or noc. nop can never match the default
172$foo = 0;
173select(OUT);
174$got = timethis($iterations, sub {++$foo}, $title, 'nop');
175select(STDOUT);
176isa_ok($got, 'Benchmark', "timethis with format");
177is ($foo, $iterations, "benchmarked code was run $iterations times");
178
179$got = $out->read();
180like ($got, qr/^$title:/, 'specify title');
181like ($got, $Nop_Pattern, 'specify format as nop');
182
183{
184    $foo = 0;
185    select(OUT);
186    my $start = time;
187    $got = timethis(-2, sub {$foo+= fib($ballast)}, $title, 'none');
188    my $end = time;
189    select(STDOUT);
190    isa_ok($got, 'Benchmark',
191           "timethis, at least 2 seconds with format 'none'");
192    ok ($foo > 0, "benchmarked code was run");
193    ok ($end - $start > 1, "benchmarked code ran for over 1 second");
194
195    $got = $out->read();
196    # Remove any warnings about having too few iterations.
197    $got =~ s/\(warning:[^\)]+\)//gs;
198    $got =~ s/^[ \t\n]+//s; # Remove all the whitespace from the beginning
199
200    is ($got, '', "format 'none' should suppress output");
201}
202
203$foo = $bar = $baz = 0;
204select(OUT);
205$got = timethese($iterations, { Foo => sub {++$foo}, Bar => '++$bar',
206                                Baz => sub {++$baz} });
207select(STDOUT);
208is(ref ($got), 'HASH', "timethese should return a hashref");
209isa_ok($got->{Foo}, 'Benchmark', "Foo value");
210isa_ok($got->{Bar}, 'Benchmark', "Bar value");
211isa_ok($got->{Baz}, 'Benchmark', "Baz value");
212eq_set([keys %$got], [qw(Foo Bar Baz)], 'should be exactly three objects');
213is ($foo, $iterations, "Foo code was run $iterations times");
214is ($bar, $iterations, "Bar code was run $iterations times");
215is ($baz, $iterations, "Baz code was run $iterations times");
216
217$got = $out->read();
218# Remove any warnings about having too few iterations.
219$got =~ s/\(warning:[^\)]+\)//gs;
220
221like ($got, qr/timing $iterations iterations of\s+Bar\W+Baz\W+Foo\W*?\.\.\./s,
222      'check title');
223# Remove the title
224$got =~ s/.*\.\.\.//s;
225like ($got, qr/\bBar\b.*\bBaz\b.*\bFoo\b/s, 'check output is in sorted order');
226like ($got, $Default_Pattern, 'should find default format somewhere');
227
228
229{ # ensure 'use strict' does not leak from Benchmark.pm into benchmarked code
230    no strict;
231    select OUT;
232
233    eval {
234        timethese( 1,
235                   { undeclared_var => q{ $i++; $i-- },
236                     symbolic_ref   => q{ $bar = 42;
237                                          $foo = 'bar';
238                                          $q = ${$foo} },
239                   },
240                   'none'
241                  );
242
243    };
244    is( $@, '', q{no strict leakage in name => 'code'} );
245
246    eval {
247        timethese( 1,
248                   { undeclared_var => sub { $i++; $i-- },
249                     symbolic_ref   => sub { $bar = 42;
250                                             $foo = 'bar';
251                                             return ${$foo} },
252                   },
253                   'none'
254                 );
255    };
256    is( $@, '', q{no strict leakage in name => sub { code }} );
257
258    # clear out buffer
259    $out->read;
260}
261
262
263my $code_to_test =  { Foo => sub {$foo+=fib($ballast-2)},
264                      Bar => sub {$bar+=fib($ballast)}};
265# Keep these for later.
266my $results;
267{
268    $foo = $bar = 0;
269    select(OUT);
270    my $start = times;
271    $results = timethese(-0.1, $code_to_test, 'none');
272    my $end = times;
273    select(STDOUT);
274
275    is(ref ($results), 'HASH', "timethese should return a hashref");
276    isa_ok($results->{Foo}, 'Benchmark', "Foo value");
277    isa_ok($results->{Bar}, 'Benchmark', "Bar value");
278    eq_set([keys %$results], [qw(Foo Bar)], 'should be exactly two objects');
279    ok ($foo > 0, "Foo code was run");
280    ok ($bar > 0, "Bar code was run");
281
282    ok (($end - $start) > 0.1, "benchmarked code ran for over 0.1 seconds");
283
284    $got = $out->read();
285    # Remove any warnings about having too few iterations.
286    $got =~ s/\(warning:[^\)]+\)//gs;
287    is ($got =~ tr/ \t\n//c, 0, "format 'none' should suppress output");
288}
289my $graph_dissassembly =
290    qr!^[ \t]+(\S+)[ \t]+(\w+)[ \t]+(\w+)[ \t]*		# Title line
291    \n[ \t]*(\w+)[ \t]+([0-9.]+(?:/s)?)[ \t]+(-+)[ \t]+(-?\d+%)[ \t]*
292    \n[ \t]*(\w+)[ \t]+([0-9.]+(?:/s)?)[ \t]+(-?\d+%)[ \t]+(-+)[ \t]*$!xm;
293
294sub check_graph_consistency {
295    my (	$ratetext, $slowc, $fastc,
296        $slowr, $slowratet, $slowslow, $slowfastt,
297        $fastr, $fastratet, $fastslowt, $fastfast)
298        = @_;
299    my $all_passed = 1;
300    $all_passed
301      &= is ($slowc, $slowr, "left col tag should be top row tag");
302    $all_passed
303      &= is ($fastc, $fastr, "right col tag should be bottom row tag");
304    $all_passed &=
305      like ($slowslow, qr/^-+/, "should be dash for comparing slow with slow");
306    $all_passed
307      &= is ($slowslow, $fastfast, "slow v slow should be same as fast v fast");
308    my $slowrate = $slowratet;
309    my $fastrate = $fastratet;
310    my ($slow_is_rate, $fast_is_rate);
311    unless ($slow_is_rate = $slowrate =~ s!/s!!) {
312        # Slow is expressed as iters per second.
313        $slowrate = 1/$slowrate if $slowrate;
314    }
315    unless ($fast_is_rate = $fastrate =~ s!/s!!) {
316        # Fast is expressed as iters per second.
317        $fastrate = 1/$fastrate if $fastrate;
318    }
319    if ($ratetext =~ /rate/i) {
320        $all_passed
321          &= ok ($slow_is_rate, "slow should be expressed as a rate");
322        $all_passed
323          &= ok ($fast_is_rate, "fast should be expressed as a rate");
324    } else {
325        $all_passed &=
326          ok (!$slow_is_rate, "slow should be expressed as a iters per second");
327        $all_passed &=
328          ok (!$fast_is_rate, "fast should be expressed as a iters per second");
329    }
330
331    (my $slowfast = $slowfastt) =~ s!%!!;
332    (my $fastslow = $fastslowt) =~ s!%!!;
333    if ($slowrate < $fastrate) {
334        pass ("slow rate is less than fast rate");
335        unless (ok ($slowfast <= 0 && $slowfast >= -100,
336                    "slowfast should be less than or equal to zero, and >= -100")) {
337          print STDERR "# slowfast $slowfast\n";
338          $all_passed = 0;
339        }
340        unless (ok ($fastslow > 0, "fastslow should be > 0")) {
341          print STDERR "# fastslow $fastslow\n";
342          $all_passed = 0;
343        }
344    } else {
345        $all_passed
346          &= is ($slowrate, $fastrate,
347                 "slow rate isn't less than fast rate, so should be the same");
348	# In OpenBSD the $slowfast is sometimes a really, really, really
349	# small number less than zero, and this gets stringified as -0.
350        $all_passed
351          &= like ($slowfast, qr/^-?0$/, "slowfast should be zero");
352        $all_passed
353          &= like ($fastslow, qr/^-?0$/, "fastslow should be zero");
354    }
355    return $all_passed;
356}
357
358sub check_graph_vs_output {
359    my ($chart, $got) = @_;
360    my (	$ratetext, $slowc, $fastc,
361        $slowr, $slowratet, $slowslow, $slowfastt,
362        $fastr, $fastratet, $fastslowt, $fastfast)
363        = $got =~ $graph_dissassembly;
364    my $all_passed
365      = check_graph_consistency (        $ratetext, $slowc, $fastc,
366                                 $slowr, $slowratet, $slowslow, $slowfastt,
367                                 $fastr, $fastratet, $fastslowt, $fastfast);
368    $all_passed
369      &= is_deeply ($chart, [['', $ratetext, $slowc, $fastc],
370                             [$slowr, $slowratet, $slowslow, $slowfastt],
371                             [$fastr, $fastratet, $fastslowt, $fastfast]],
372                    "check the chart layout matches the formatted output");
373    unless ($all_passed) {
374      print STDERR "# Something went wrong there. I got this chart:\n";
375      print STDERR "# $_\n" foreach split /\n/, $got;
376    }
377}
378
379sub check_graph {
380    my ($title, $row1, $row2) = @_;
381    is (scalar @$title, 4, "Four entries in title row");
382    is (scalar @$row1, 4, "Four entries in first row");
383    is (scalar @$row2, 4, "Four entries in second row");
384    is (shift @$title, '', "First entry of output graph should be ''");
385    check_graph_consistency (@$title, @$row1, @$row2);
386}
387
388{
389    select(OUT);
390    my $start = times;
391    my $chart = cmpthese( -0.1, { a => "++\$i", b => "\$i = sqrt(\$i++)" }, "auto" ) ;
392    my $end = times;
393    select(STDOUT);
394    ok (($end - $start) > 0.05, "benchmarked code ran for over 0.05 seconds");
395
396    $got = $out->read();
397    # Remove any warnings about having too few iterations.
398    $got =~ s/\(warning:[^\)]+\)//gs;
399
400    like ($got, qr/running\W+a\W+b.*?for at least 0\.1 CPU second/s,
401          'check title');
402    # Remove the title
403    $got =~ s/.*\.\.\.//s;
404    like ($got, $Default_Pattern, 'should find default format somewhere');
405    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
406    check_graph_vs_output ($chart, $got);
407}
408
409# Not giving auto should suppress timethese results.
410{
411    select(OUT);
412    my $start = times;
413    my $chart = cmpthese( -0.1, { a => "++\$i", b => "\$i = sqrt(\$i++)" } ) ;
414    my $end = times;
415    select(STDOUT);
416    ok (($end - $start) > 0.05, "benchmarked code ran for over 0.05 seconds");
417
418    $got = $out->read();
419    # Remove any warnings about having too few iterations.
420    $got =~ s/\(warning:[^\)]+\)//gs;
421
422    unlike ($got, qr/running\W+a\W+b.*?for at least 0\.1 CPU second/s,
423          'should not have title');
424    # Remove the title
425    $got =~ s/.*\.\.\.//s;
426    unlike ($got, $Default_Pattern, 'should not find default format somewhere');
427    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
428    check_graph_vs_output ($chart, $got);
429}
430
431{
432    $foo = $bar = 0;
433    select(OUT);
434    my $chart = cmpthese( 10, $code_to_test, 'nop' ) ;
435    select(STDOUT);
436    ok ($foo > 0, "Foo code was run");
437    ok ($bar > 0, "Bar code was run");
438
439    $got = $out->read();
440    # Remove any warnings about having too few iterations.
441    $got =~ s/\(warning:[^\)]+\)//gs;
442    like ($got, qr/timing 10 iterations of\s+Bar\W+Foo\W*?\.\.\./s,
443      'check title');
444    # Remove the title
445    $got =~ s/.*\.\.\.//s;
446    like ($got, $Nop_Pattern, 'specify format as nop');
447    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
448    check_graph_vs_output ($chart, $got);
449}
450
451{
452    $foo = $bar = 0;
453    select(OUT);
454    my $chart = cmpthese( 10, $code_to_test, 'none' ) ;
455    select(STDOUT);
456    ok ($foo > 0, "Foo code was run");
457    ok ($bar > 0, "Bar code was run");
458
459    $got = $out->read();
460    # Remove any warnings about having too few iterations.
461    $got =~ s/\(warning:[^\)]+\)//gs;
462    $got =~ s/^[ \t\n]+//s; # Remove all the whitespace from the beginning
463    is ($got, '', "format 'none' should suppress output");
464    is (ref $chart, 'ARRAY', "output should be an array ref");
465    # Some of these will go bang if the preceding test fails. There will be
466    # a big clue as to why, from the previous test's diagnostic
467    is (ref $chart->[0], 'ARRAY', "output should be an array of arrays");
468    check_graph (@$chart);
469}
470
471{
472    $foo = $bar = 0;
473    select(OUT);
474    my $chart = cmpthese( $results ) ;
475    select(STDOUT);
476    is ($foo, 0, "Foo code was not run");
477    is ($bar, 0, "Bar code was not run");
478
479    $got = $out->read();
480    ok ($got !~ /\.\.\./s, 'check that there is no title');
481    like ($got, $graph_dissassembly, "Should find the output graph somewhere");
482    check_graph_vs_output ($chart, $got);
483}
484
485{
486    $foo = $bar = 0;
487    select(OUT);
488    my $chart = cmpthese( $results, 'none' ) ;
489    select(STDOUT);
490    is ($foo, 0, "Foo code was not run");
491    is ($bar, 0, "Bar code was not run");
492
493    $got = $out->read();
494    is ($got, '', "'none' should suppress all output");
495    is (ref $chart, 'ARRAY', "output should be an array ref");
496    # Some of these will go bang if the preceding test fails. There will be
497    # a big clue as to why, from the previous test's diagnostic
498    is (ref $chart->[0], 'ARRAY', "output should be an array of arrays");
499    check_graph (@$chart);
500}
501
502###}my $out = tie *OUT, 'TieOut'; my ($got); ###
503
504my $debug = tie *STDERR, 'TieOut';
505
506$bar = 0;
507isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
508is ($bar, 5, "benchmarked code was run 5 times");
509is ($debug->read(), '', "There was no debug output");
510
511Benchmark->debug(1);
512
513$bar = 0;
514select(OUT);
515$got = timeit(5, '++$bar');
516select(STDOUT);
517isa_ok($got, 'Benchmark', "timeit eval");
518is ($bar, 5, "benchmarked code was run 5 times");
519is ($out->read(), '', "There was no STDOUT output with debug enabled");
520isnt ($debug->read(), '', "There was STDERR debug output with debug enabled");
521
522Benchmark->debug(0);
523
524$bar = 0;
525isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
526is ($bar, 5, "benchmarked code was run 5 times");
527is ($debug->read(), '', "There was no debug output debug disabled");
528
529undef $debug;
530untie *STDERR;
531
532# To check the cache we are poking where we don't belong, inside the namespace.
533# The way benchmark is written We can't actually check whehter the cache is
534# being used, merely what's become cached.
535
536clearallcache();
537my @before_keys = keys %Benchmark::Cache;
538$bar = 0;
539isa_ok(timeit(5, '++$bar'), 'Benchmark', "timeit eval");
540is ($bar, 5, "benchmarked code was run 5 times");
541my @after5_keys = keys %Benchmark::Cache;
542$bar = 0;
543isa_ok(timeit(10, '++$bar'), 'Benchmark', "timeit eval");
544is ($bar, 10, "benchmarked code was run 10 times");
545ok (!eq_array ([keys %Benchmark::Cache], \@after5_keys), "10 differs from 5");
546
547clearcache(10);
548# Hash key order will be the same if there are the same keys.
549is_deeply ([keys %Benchmark::Cache], \@after5_keys,
550           "cleared 10, only cached results for 5 should remain");
551
552clearallcache();
553is_deeply ([keys %Benchmark::Cache], \@before_keys,
554           "back to square 1 when we clear the cache again?");
555
556
557{   # Check usage error messages
558    my %usage = %Benchmark::_Usage;
559    delete $usage{runloop};  # not public, not worrying about it just now
560
561    my @takes_no_args = qw(clearallcache disablecache enablecache);
562
563    my %cmpthese = ('forgot {}' => 'cmpthese( 42, foo => sub { 1 } )',
564                     'not result' => 'cmpthese(42)',
565                     'array ref'  => 'cmpthese( 42, [ foo => sub { 1 } ] )',
566                    );
567    while( my($name, $code) = each %cmpthese ) {
568        eval $code;
569        is( $@, $usage{cmpthese}, "cmpthese usage: $name" );
570    }
571
572    my %timethese = ('forgot {}'  => 'timethese( 42, foo => sub { 1 } )',
573                       'no code'    => 'timethese(42)',
574                       'array ref'  => 'timethese( 42, [ foo => sub { 1 } ] )',
575                      );
576
577    while( my($name, $code) = each %timethese ) {
578        eval $code;
579        is( $@, $usage{timethese}, "timethese usage: $name" );
580    }
581
582
583    while( my($func, $usage) = each %usage ) {
584        next if grep $func eq $_, @takes_no_args;
585        eval "$func()";
586        is( $@, $usage, "$func usage: no args" );
587    }
588
589    foreach my $func (@takes_no_args) {
590        eval "$func(42)";
591        is( $@, $usage{$func}, "$func usage: with args" );
592    }
593}
594
595
596package TieOut;
597
598sub TIEHANDLE {
599    my $class = shift;
600    bless(\( my $ref = ''), $class);
601}
602
603sub PRINT {
604    my $self = shift;
605    $$self .= join('', @_);
606}
607
608sub PRINTF {
609    my $self = shift;
610    $$self .= sprintf shift, @_;
611}
612
613sub read {
614    my $self = shift;
615    return substr($$self, 0, length($$self), '');
616}
617