MESSAGE
| DATE | 2016-12-17 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Learn] irc thread on the use of object methods in threads
|
From learn-bounces-at-nylxs.com Sat Dec 17 17:28:18 2016
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Subject: [Learn] irc thread on the use of object methods in threads
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Sender: "Learn"
3:53:37 PM - mrbrklyn: wow - I just learned I can't send a member
function to a thread... which really sucks.
3:53:41 PM - XCE [~XCE-at-2601:646:8280:3280:849a:8bd9:9b61:dae7] entered
the room.
3:53:53 PM - eraz: mrbrklyn: how would that even work.
3:53:58 PM - melita [~melita-at-2601:645:4000:ccd0:1092:2f75:1b74:5ab0]
entered the room.
3:53:59 PM - megaTherion: makes not much sense
3:54:26 PM - litb: what do you mean by "send"
3:54:35 PM - mrbrklyn: why would it not work if the thread is inside an
object.
3:54:42 PM - litb: can you please send the question to me
3:54:47 PM - mrbrklyn: I ask out of ignorance
3:54:48 PM - megaTherion: I agree, elaborate what send means in this context
3:55:31 PM - mrbrklyn: std::thread paint(read_chunk);
3:55:51 PM - mrbrklyn: where read_chunk is a member of on object of
class Image
3:55:57 PM - minus: basically, you need to bind `this`
3:56:11 PM - megaTherion: I think "send" isnt really the best word for
this ^^
3:56:16 PM - mrbrklyn: minus, can you elaborate?
3:56:27 PM - litb: mrbrklyn, instead of read_chunk you need to say
[this]{read_chunk();}
3:56:39 PM - minus: std::thread paint([this] { read_chunk(); }); should work
3:56:47 PM - minus: eh, i'm too slow :<
3:57:17 PM - minus: member functions take the this pointer of the object
as first, hidden parameter
3:57:18 PM - mrbrklyn: with square brackets
3:57:36 PM - byte512 has left the room (Quit: Ping timeout: 252 seconds).
3:57:37 PM - litb: mrbrklyn, it is a lambda
3:57:58 PM - eraz: {[]{}();}
3:57:59 PM - geordi:
3:58:08 PM - litb: i would prefer one more paren
3:58:10 PM - mrbrklyn: ahhh . .. a whole new concept :)
3:58:20 PM - eraz: {[](){[](){}();};}
3:58:21 PM - geordi:
3:58:41 PM - eraz: <3 lambdas <3
3:58:42 PM - melita has left the room (Quit: Ping timeout: 258 seconds).
3:58:43 PM - salamanderrake
[~quassel-at-2605:a000:1229:c036:39f4:3bbe:4bf0:c03] entered the room.
3:59:09 PM - litb: geordi, add *+ before first [
3:59:09 PM - geordi:
3:59:17 PM - o]: ew
3:59:21 PM - minus: need =3D> for more concise lambdas
3:59:30 PM - megaTherion: indeed
3:59:31 PM - o]: geordi,show
3:59:31 PM - geordi: {*+[](){[](){}();};}
3:59:39 PM - eraz: geordi, replace * with *******
3:59:40 PM - geordi:
3:59:46 PM - o]: :(((((((((
3:59:47 PM - litb: figured the lambda beard needs a proper nose with eye
3:59:54 PM - minus: how is that even valid
4:00:02 PM - Rarglepuff [~Rarglepuf-at-cpe-74-75-107-152.maine.res.rr.com]
entered the room.
4:00:03 PM - o]: operator+ on lambdas huh
4:00:04 PM - eraz: geordi, replace {[] with {*******+[]
4:00:04 PM - geordi: error: wrong type argument to unary plus
4:00:06 PM - eraz: dammit
4:00:09 PM - minus: << +[]{}();
4:00:09 PM - geordi: Same error.
4:00:26 PM - Rarglepuff has left the room (Quit: Remote host closed the
connection).
4:00:32 PM - eraz: << (+[]{})();
4:00:32 PM - geordi: error: no match for 'operator<<' in 'cout <<
(+ main(int, char**)::{}.main(int,
char**)::::operator void (*)()())()' (operand types are
'ostream {aka ostream}' and 'void')
4:00:37 PM - litb: lol
4:00:43 PM - eraz: << (+[]{return int{}})();
4:00:43 PM - geordi: error: expected ';' before '}' token
4:00:46 PM - eraz: << (+[]{return int{};})();
4:00:46 PM - geordi: 0
4:00:49 PM - mrbrklyn: what is a lamda and why do I need it here?
4:00:54 PM - megaTherion: ...
4:00:57 PM - Rarglepuff [~Rarglepuf-at-cpe-74-75-107-152.maine.res.rr.com]
entered the room.
4:00:58 PM - eraz: mrbrklyn: do you know what function objects are?
4:01:04 PM - o]: !grab mrbrklyn
4:01:05 PM - nolyc: By your command.
4:01:13 PM - litb: mrbrklyn, because a member function name evaluates to
an rvalue of function type and the only supported operation on it is to
call it right away
4:01:16 PM - willy23123 has left the room (Quit: Colloquy for iPhone -
http://colloquy.mobi).
4:01:38 PM - megaTherion: mrbrklyn: you're C++98?
4:01:59 PM - eraz: mrbrklyn: well, actually, you could just watch this
(very good) video on lambdas. https://youtu.be/WXeu4fj3zOs
4:02:01 PM - minus: std::thread doesn't exist in C++98, so he can't be
4:02:02 PM - urlgrabber [~urlgrabbe-at-www.ladio.me] entered the room.
4:02:31 PM - mrbrklyn: gcc version 6.2.1 20160830 (GCC)
4:02:54 PM - litb: mrbrklyn, alternatively,
bind(&decay_t<*decltype(this)>::read_chunk, this) should work
4:02:55 PM - eraz: mrbrklyn: I think megaTherion was asking about your
area of comfort regarding C++.
4:03:15 PM - megaTherion: comfort or knowledge :)
4:03:27 PM - megaTherion: was just curious
4:03:58 PM - minus: litb: not decltype(*this)?
4:04:03 PM - mrbrklyn: Well, I'm deaf so videos are not great
4:04:04 PM - litb: yes :D
4:04:05 PM - eraz: minus: that returns a reference.
4:04:17 PM - eraz: References don't have members. :)
4:04:23 PM - megaTherion: mrbrklyn: then you want a book
4:04:25 PM - mrbrklyn: C++, fairly familiar going back to using it since
1994
4:04:42 PM - mrbrklyn: never threading until now
4:04:45 PM - megaTherion: mrbrklyn: effective modern C++ by Scott Meyers
might bring you up to C++11/14 then
4:04:49 PM - allen29 [~all-at-unaffiliated/allen29] entered the room.
4:04:59 PM - minus: ^ reading that right now, good book
4:05:19 PM - eraz: Still on the way (shipping). Excited to have a copy. :)
4:05:34 PM - mrbrklyn: C++ concurancy - anthony williams
4:05:35 PM - mrbrklyn: ?
4:06:20 PM - litb: yes get it
4:06:33 PM - matkatmusic
[~matkatmus-at-pool-173-56-226-234.nycmny.fios.verizon.net] entered the room.
4:07:59 PM - mrbrklyn: I have the latest C++FifthPrimer Edition Stanley
B. Lippman Jos=C3=A9e Lajoie Barbara E. Moo also
4:09:19 PM * eraz gives mrbrklyn a thumbs up
4:09:31 PM - KAHR-Alpha has left the room (Quit: Remote host closed the
connection).
4:11:24 PM - minus: eraz =E2=94=82 minus: that returns a reference. =E2=86=
=90
decay_t instead of decay_t<*decltype(this)> is what i meant
4:11:46 PM - Sylph-DS [~Sylph-at-145.136.49.141] entered the room.
4:13:15 PM - eraz: minus: ah, I thought somethingl looked off about that. :P
4:13:29 PM - mrbrklyn: The C++ Programming Language Fourth Edition
Bjarne Stroustrup also
4:13:37 PM - RedOrangeZ [~RedOrange-at-c-73-30-227-113.hsd1.pa.comcast.net]
entered the room.
4:13:38 PM - FreeBirdLjj has left the room (Quit: Remote host closed the
connection).
4:13:55 PM - blackbird_ [~blackbird-at-197.2.130.228] entered the room.
4:15:15 PM - AquaL1te has left the room (Quit: leaving).
4:16:17 PM - blackbird1 has left the room (Quit: Ping timeout: 268 seconds).
4:17:48 PM - mrbrklyn: how about creating a warpper function for the
member call?
4:18:18 PM - megaTherion: mrbrklyn: the lambda results in an closure,
which is exacly such a thing
4:18:28 PM - mrbrklyn:
http://stackoverflow.com/questions/22749787/invalid-use-of-non-static-membe=
r-function-in-qt#22749866
4:18:58 PM - mrbrklyn: OK what is the inherent error that I'm hitting though
4:19:17 PM - megaTherion: mrbrklyn: if you're not comfortable with
lambda's (yet), you can also use std::bind which does what you want as well
4:19:19 PM - o]: !give mrbrklyn basic
4:19:21 PM - nolyc: mrbrklyn: If you're very new to C++ and have not yet
found your footing, ##c++-basic may be able to guide you along your
first steps.
4:19:26 PM - mrbrklyn: I'm not understanding the nature of the problem,
even though I can use a receipe to fix it
4:19:31 PM - o]: ahh they changed the factoid :( why
4:19:33 PM - megaTherion: (you may know bind1st, bind2nd)
4:19:52 PM - eraz: o]: it's a lot nicer. :P
4:19:55 PM - o]: megaTherion: eww. stop throwing shit at the channel
4:20:05 PM - mrbrklyn: why can't the thread object use the implied this->
4:20:07 PM - eraz: megaTherion: do not mention those horrible things.
4:20:17 PM - megaTherion: o]: what's the issue?
4:20:27 PM - o]: you are recommending deprecated shit here. don't do that
4:20:28 PM - megaTherion: arent they valid in C++98?
4:20:33 PM - megaTherion: haha
4:20:40 PM - megaTherion: o]: you seem to live in an ideal world
4:20:49 PM * megaTherion still has to do C++98 coding from time to time
4:20:49 PM - o]: it is almost 2017
4:20:56 PM - megaTherion: o]: old projects wont give a shit
4:21:04 PM - o]: I already refactored all of them
4:21:06 PM - megaTherion: they are there and they wont go away
4:21:14 PM - megaTherion: o]: and you paid for refactoring?
4:21:17 PM - o]: your shit doesn't go away because you are lazy
4:21:23 PM - megaTherion: *lool*
4:21:25 PM - o]: or avaricious
4:21:39 PM - megaTherion: o]: Im not a freelancer, I dont decide what
will be done or not
4:21:56 PM - o]: wtf being a freelancer has to do or not with doing a
good job?
4:22:08 PM - megaTherion: you're completly missing the point
4:22:17 PM - o]: I don't live in an ideal world. you are the one who
lives in a distopic world
4:22:18 PM - megaTherion: Im not the one who decides if the code will be
refactored or not
4:22:23 PM - megaTherion: pure and simple
4:22:30 PM - anuxivm [~anuxi-at-92.177.99.40] entered the room.
4:22:55 PM - o]: please don't spread your bad habits here
4:23:06 PM - megaTherion: Im only telling you from real life work :)
4:23:08 PM - megaTherion: not your IRC dreams
4:23:17 PM - o]: and you are implying that I don't do real work
4:23:19 PM - eraz: lol
4:23:28 PM - minus: straying off topic a bit here
4:23:28 PM - o]: you are so full of yourself
4:23:31 PM - megaTherion: Im implying that you might have less than 10y
experience
4:23:32 PM - o]: yup
4:23:37 PM - martinium has left the room (Quit: Ping timeout: 250 seconds).
4:23:47 PM - megaTherion: C++ is around a lot longer
4:23:48 PM - o]: megaTherion: I code since 1985, you asshole
4:24:00 PM - P4Titan: let's not hate guys
4:24:05 PM - P4Titan: c'mon
4:24:10 PM * eraz is a 96... ._.
4:24:22 PM - minus: go to sleep kiddo
4:24:23 PM - megaTherion: o]: I'll simply ignore you, you're too
immature for my taste
4:24:35 PM - o]: awesome. good bye
4:24:43 PM - melita [~melita-at-2601:645:4000:ccd0:1092:2f75:1b74:5ab0]
entered the room.
4:24:49 PM - eraz: !next2 (x2)
4:24:54 PM - eraz: wait really?
4:24:57 PM - eraz: !next2
4:24:57 PM - o]: !give megaTherion restrict
4:24:58 PM - nolyc: Another dissatisfied customer, next!
4:24:59 PM - nolyc: megaTherion: If you insist on using only a
restricted subset of C++, then know that our interest in helping you is
inversely proportional to the severity of the restrictions.
4:25:11 PM - megaTherion: *shrugs*
4:25:13 PM - eraz: I like that factoid. :)
4:25:19 PM - o]: it is pretty accurate
4:25:21 PM - megaTherion: but it missed the point as well
4:25:26 PM - megaTherion: C++98 has no lambdas
4:25:36 PM - o]: /j ##C++98
4:25:46 PM - minus: C++98 has no std::thread
4:25:50 PM - o]: :)
4:25:51 PM - mrbrklyn: reminds me of tux in the old perl irc channels
4:25:54 PM - megaTherion: indeed
4:25:56 PM - eraz: No lambdas? The horror!
4:26:06 PM - talisein [~talisein-at-april-fools/2013/sixth/talisein]
entered the room.
4:26:17 PM - megaTherion: eraz: why... you can do a lot of good code
with C++98, when people tried to enforce their C code on a C++ compiler
back in the days
4:26:23 PM - blackbird1 [~blackbird-at-197.0.185.68] entered the room.
4:26:33 PM - blueness_ has left the room (Quit: blueness_).
4:26:34 PM - megaTherion: you can do very clean code with C++98 in fact,
its great to know these things for a real life job
4:26:39 PM - ville [~ville-at-87-95-199-161.bb.dnainternet.fi] entered the
room.
4:26:39 PM - eraz: megaTherion: But... but... lambdas!!
4:26:51 PM - o]: you can do clean C++98 code, but we don't have to
4:27:03 PM - o]: it is lots of boilerplate, which makes it more error
prone and tedious
4:27:17 PM - o]: and no move, which forces the poor coder to create move
functions. more boilershit
4:27:41 PM - mrbrklyn: there is a bias that newer is always better,
which as you grow older, you relize that just isn't true at all
4:27:43 PM - eraz: oh right, no move semantics prior C++11... omg.
4:27:52 PM - megaTherion: eraz: just remembers me about a friend who
just got his first job and leaving university, I told him begin with
C++98 - learn the basics, he disagreed of course... one of the first
task was looking at some C++98 code and no C++11 was available (some
embedded platform /WinCE stuff) :)
4:27:56 PM - megaTherion: and thats just real life
4:28:07 PM - mrbrklyn: regardless, why can't the thread object take the
implied this ?
4:28:08 PM - eraz: megaTherion: I know, I'm half-kidding here. :P
4:28:13 PM - eraz: I just like lambdas. :3
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