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30 | |
30 | |
31 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
31 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
32 | policy* and AnyEvent is *small and efficient*. |
32 | policy* and AnyEvent is *small and efficient*. |
33 | |
33 | |
34 | First and foremost, *AnyEvent is not an event model* itself, it only |
34 | First and foremost, *AnyEvent is not an event model* itself, it only |
35 | interfaces to whatever event model the main program happens to use in a |
35 | interfaces to whatever event model the main program happens to use, in a |
36 | pragmatic way. For event models and certain classes of immortals alike, |
36 | pragmatic way. For event models and certain classes of immortals alike, |
37 | the statement "there can only be one" is a bitter reality: In general, |
37 | the statement "there can only be one" is a bitter reality: In general, |
38 | only one event loop can be active at the same time in a process. |
38 | only one event loop can be active at the same time in a process. |
39 | AnyEvent helps hiding the differences between those event loops. |
39 | AnyEvent cannot change this, but it can hide the differences between |
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40 | those event loops. |
40 | |
41 | |
41 | The goal of AnyEvent is to offer module authors the ability to do event |
42 | The goal of AnyEvent is to offer module authors the ability to do event |
42 | programming (waiting for I/O or timer events) without subscribing to a |
43 | programming (waiting for I/O or timer events) without subscribing to a |
43 | religion, a way of living, and most importantly: without forcing your |
44 | religion, a way of living, and most importantly: without forcing your |
44 | module users into the same thing by forcing them to use the same event |
45 | module users into the same thing by forcing them to use the same event |
45 | model you use. |
46 | model you use. |
46 | |
47 | |
47 | For modules like POE or IO::Async (which is a total misnomer as it is |
48 | For modules like POE or IO::Async (which is a total misnomer as it is |
48 | actually doing all I/O *synchronously*...), using them in your module is |
49 | actually doing all I/O *synchronously*...), using them in your module is |
49 | like joining a cult: After you joined, you are dependent on them and you |
50 | like joining a cult: After you joined, you are dependent on them and you |
50 | cannot use anything else, as it is simply incompatible to everything |
51 | cannot use anything else, as they are simply incompatible to everything |
51 | that isn't itself. What's worse, all the potential users of your module |
52 | that isn't them. What's worse, all the potential users of your module |
52 | are *also* forced to use the same event loop you use. |
53 | are *also* forced to use the same event loop you use. |
53 | |
54 | |
54 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
55 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
55 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
56 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
56 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
57 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
57 | module uses one of those, every user of your module has to use it, too. |
58 | module uses one of those, every user of your module has to use it, too. |
58 | But if your module uses AnyEvent, it works transparently with all event |
59 | But if your module uses AnyEvent, it works transparently with all event |
59 | models it supports (including stuff like POE and IO::Async, as long as |
60 | models it supports (including stuff like IO::Async, as long as those use |
60 | those use one of the supported event loops. It is trivial to add new |
61 | one of the supported event loops. It is trivial to add new event loops |
61 | event loops to AnyEvent, too, so it is future-proof). |
62 | to AnyEvent, too, so it is future-proof). |
62 | |
63 | |
63 | In addition to being free of having to use *the one and only true event |
64 | In addition to being free of having to use *the one and only true event |
64 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
65 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
65 | modules, you get an enormous amount of code and strict rules you have to |
66 | modules, you get an enormous amount of code and strict rules you have to |
66 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
67 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
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146 | |
147 | |
147 | I/O WATCHERS |
148 | I/O WATCHERS |
148 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
149 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
149 | the following mandatory key-value pairs as arguments: |
150 | the following mandatory key-value pairs as arguments: |
150 | |
151 | |
151 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events. |
152 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events |
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153 | (AnyEvent might or might not keep a reference to this file handle). |
152 | "poll" must be a string that is either "r" or "w", which creates a |
154 | "poll" must be a string that is either "r" or "w", which creates a |
153 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
155 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
154 | is the callback to invoke each time the file handle becomes ready. |
156 | is the callback to invoke each time the file handle becomes ready. |
155 | |
157 | |
156 | Although the callback might get passed parameters, their value and |
158 | Although the callback might get passed parameters, their value and |
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163 | |
165 | |
164 | Some event loops issue spurious readyness notifications, so you should |
166 | Some event loops issue spurious readyness notifications, so you should |
165 | always use non-blocking calls when reading/writing from/to your file |
167 | always use non-blocking calls when reading/writing from/to your file |
166 | handles. |
168 | handles. |
167 | |
169 | |
168 | Example: |
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169 | |
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170 | # wait for readability of STDIN, then read a line and disable the watcher |
170 | Example: wait for readability of STDIN, then read a line and disable the |
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171 | watcher. |
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172 | |
171 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
173 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
172 | chomp (my $input = <STDIN>); |
174 | chomp (my $input = <STDIN>); |
173 | warn "read: $input\n"; |
175 | warn "read: $input\n"; |
174 | undef $w; |
176 | undef $w; |
175 | }); |
177 | }); |
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184 | |
186 | |
185 | Although the callback might get passed parameters, their value and |
187 | Although the callback might get passed parameters, their value and |
186 | presence is undefined and you cannot rely on them. Portable AnyEvent |
188 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | callbacks cannot use arguments passed to time watcher callbacks. |
189 | callbacks cannot use arguments passed to time watcher callbacks. |
188 | |
190 | |
189 | The timer callback will be invoked at most once: if you want a repeating |
191 | The callback will normally be invoked once only. If you specify another |
190 | timer you have to create a new watcher (this is a limitation by both Tk |
192 | parameter, "interval", as a strictly positive number (> 0), then the |
191 | and Glib). |
193 | callback will be invoked regularly at that interval (in fractional |
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194 | seconds) after the first invocation. If "interval" is specified with a |
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195 | false value, then it is treated as if it were missing. |
192 | |
196 | |
193 | Example: |
197 | The callback will be rescheduled before invoking the callback, but no |
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198 | attempt is done to avoid timer drift in most backends, so the interval |
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199 | is only approximate. |
194 | |
200 | |
195 | # fire an event after 7.7 seconds |
201 | Example: fire an event after 7.7 seconds. |
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202 | |
196 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
203 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
197 | warn "timeout\n"; |
204 | warn "timeout\n"; |
198 | }); |
205 | }); |
199 | |
206 | |
200 | # to cancel the timer: |
207 | # to cancel the timer: |
201 | undef $w; |
208 | undef $w; |
202 | |
209 | |
203 | Example 2: |
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204 | |
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205 | # fire an event after 0.5 seconds, then roughly every second |
210 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
206 | my $w; |
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207 | |
211 | |
208 | my $cb = sub { |
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209 | # cancel the old timer while creating a new one |
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210 | $w = AnyEvent->timer (after => 1, cb => $cb); |
212 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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213 | warn "timeout\n"; |
211 | }; |
214 | }; |
212 | |
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213 | # start the "loop" by creating the first watcher |
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214 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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215 | |
215 | |
216 | TIMING ISSUES |
216 | TIMING ISSUES |
217 | There are two ways to handle timers: based on real time (relative, "fire |
217 | There are two ways to handle timers: based on real time (relative, "fire |
218 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
218 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
219 | o'clock"). |
219 | o'clock"). |
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295 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
295 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
296 | account. |
296 | account. |
297 | |
297 | |
298 | SIGNAL WATCHERS |
298 | SIGNAL WATCHERS |
299 | You can watch for signals using a signal watcher, "signal" is the signal |
299 | You can watch for signals using a signal watcher, "signal" is the signal |
300 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
300 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
301 | whenever a signal occurs. |
301 | callback to be invoked whenever a signal occurs. |
302 | |
302 | |
303 | Although the callback might get passed parameters, their value and |
303 | Although the callback might get passed parameters, their value and |
304 | presence is undefined and you cannot rely on them. Portable AnyEvent |
304 | presence is undefined and you cannot rely on them. Portable AnyEvent |
305 | callbacks cannot use arguments passed to signal watcher callbacks. |
305 | callbacks cannot use arguments passed to signal watcher callbacks. |
306 | |
306 | |
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698 | AnyEvent::Util |
698 | AnyEvent::Util |
699 | Contains various utility functions that replace often-used but |
699 | Contains various utility functions that replace often-used but |
700 | blocking functions such as "inet_aton" by event-/callback-based |
700 | blocking functions such as "inet_aton" by event-/callback-based |
701 | versions. |
701 | versions. |
702 | |
702 | |
703 | AnyEvent::Handle |
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704 | Provide read and write buffers and manages watchers for reads and |
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705 | writes. |
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706 | |
|
|
707 | AnyEvent::Socket |
703 | AnyEvent::Socket |
708 | Provides various utility functions for (internet protocol) sockets, |
704 | Provides various utility functions for (internet protocol) sockets, |
709 | addresses and name resolution. Also functions to create non-blocking |
705 | addresses and name resolution. Also functions to create non-blocking |
710 | tcp connections or tcp servers, with IPv6 and SRV record support and |
706 | tcp connections or tcp servers, with IPv6 and SRV record support and |
711 | more. |
707 | more. |
712 | |
708 | |
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|
709 | AnyEvent::Handle |
|
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710 | Provide read and write buffers, manages watchers for reads and |
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711 | writes, supports raw and formatted I/O, I/O queued and fully |
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712 | transparent and non-blocking SSL/TLS. |
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713 | |
713 | AnyEvent::DNS |
714 | AnyEvent::DNS |
714 | Provides rich asynchronous DNS resolver capabilities. |
715 | Provides rich asynchronous DNS resolver capabilities. |
715 | |
716 | |
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717 | AnyEvent::HTTP |
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718 | A simple-to-use HTTP library that is capable of making a lot of |
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719 | concurrent HTTP requests. |
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720 | |
716 | AnyEvent::HTTPD |
721 | AnyEvent::HTTPD |
717 | Provides a simple web application server framework. |
722 | Provides a simple web application server framework. |
718 | |
723 | |
719 | AnyEvent::FastPing |
724 | AnyEvent::FastPing |
720 | The fastest ping in the west. |
725 | The fastest ping in the west. |
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726 | |
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727 | AnyEvent::DBI |
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728 | Executes DBI requests asynchronously in a proxy process. |
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729 | |
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730 | AnyEvent::AIO |
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731 | Truly asynchronous I/O, should be in the toolbox of every event |
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|
732 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
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733 | together. |
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734 | |
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|
735 | AnyEvent::BDB |
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736 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
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737 | fuses BDB and AnyEvent together. |
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738 | |
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739 | AnyEvent::GPSD |
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740 | A non-blocking interface to gpsd, a daemon delivering GPS |
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741 | information. |
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742 | |
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743 | AnyEvent::IGS |
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744 | A non-blocking interface to the Internet Go Server protocol (used by |
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745 | App::IGS). |
721 | |
746 | |
722 | Net::IRC3 |
747 | Net::IRC3 |
723 | AnyEvent based IRC client module family. |
748 | AnyEvent based IRC client module family. |
724 | |
749 | |
725 | Net::XMPP2 |
750 | Net::XMPP2 |
… | |
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732 | Event::ExecFlow |
757 | Event::ExecFlow |
733 | High level API for event-based execution flow control. |
758 | High level API for event-based execution flow control. |
734 | |
759 | |
735 | Coro |
760 | Coro |
736 | Has special support for AnyEvent via Coro::AnyEvent. |
761 | Has special support for AnyEvent via Coro::AnyEvent. |
737 | |
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|
738 | AnyEvent::AIO, IO::AIO |
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|
739 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
740 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
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|
741 | together. |
|
|
742 | |
|
|
743 | AnyEvent::BDB, BDB |
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|
744 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
|
|
745 | fuses IO::AIO and AnyEvent together. |
|
|
746 | |
762 | |
747 | IO::Lambda |
763 | IO::Lambda |
748 | The lambda approach to I/O - don't ask, look there. Can use |
764 | The lambda approach to I/O - don't ask, look there. Can use |
749 | AnyEvent. |
765 | AnyEvent. |
750 | |
766 | |
… | |
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803 | conditions, such as not being able to load the event model specified |
819 | conditions, such as not being able to load the event model specified |
804 | by "PERL_ANYEVENT_MODEL". |
820 | by "PERL_ANYEVENT_MODEL". |
805 | |
821 | |
806 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
822 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
807 | event model it chooses. |
823 | event model it chooses. |
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824 | |
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825 | "PERL_ANYEVENT_STRICT" |
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826 | AnyEvent does not do much argument checking by default, as thorough |
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827 | argument checking is very costly. Setting this variable to a true |
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828 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
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829 | thoroughly check the arguments passed to most method calls. If it |
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830 | finds any problems it will croak. |
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|
831 | |
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|
832 | In other words, enables "strict" mode. |
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833 | |
|
|
834 | Unlike "use strict" it is definitely recommended ot keep it off in |
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|
835 | production. |
808 | |
836 | |
809 | "PERL_ANYEVENT_MODEL" |
837 | "PERL_ANYEVENT_MODEL" |
810 | This can be used to specify the event model to be used by AnyEvent, |
838 | This can be used to specify the event model to be used by AnyEvent, |
811 | before auto detection and -probing kicks in. It must be a string |
839 | before auto detection and -probing kicks in. It must be a string |
812 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
840 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
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1274 | |
1302 | |
1275 | use AnyEvent; |
1303 | use AnyEvent; |
1276 | |
1304 | |
1277 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1305 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1278 | be used to probe what backend is used and gain other information (which |
1306 | be used to probe what backend is used and gain other information (which |
1279 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1307 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
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|
1308 | and $ENV{PERL_ANYEGENT_STRICT}. |
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1309 | |
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1310 | BUGS |
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1311 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
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1312 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
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1313 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
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1314 | annoying mamleaks, such as leaking on "map" and "grep" but it is usually |
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1315 | not as pronounced). |
1280 | |
1316 | |
1281 | SEE ALSO |
1317 | SEE ALSO |
1282 | Utility functions: AnyEvent::Util. |
1318 | Utility functions: AnyEvent::Util. |
1283 | |
1319 | |
1284 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1320 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |