Re^3: eval order of args to a sub

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Re^4: eval order of args to a sub by Joost (Canon) on May 30, 2007 at 19:42 UTC
Hmm.. now that I re-read that, it doesn't mean what I thought it meant. As for the update: If the arguments were passed by value, and evaluated right-to-left, you'd expect `a($i--,++$i)` to pass `(2,2)` "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l] [select]
Re^5: eval order of args to a sub by ikegami (Patriarch) on May 30, 2007 at 20:28 UTC
You were looking at the wrong section of the document. If you check the Operator Precedence and Associativity table, you'll notice the list seperator is left-associative, and that operator associativity is defined as follows: Operator associativity defines what happens if a sequence of the same operators is used one after another: whether the evaluator will evaluate the left operations first or the right. I can confirm that is how it works on my system (ActivePerl 5.8.8 on WinXP).	[reply]
Re^6: eval order of args to a sub by mrpeabody (Friar) on Jun 03, 2007 at 11:15 UTC
Mmm, that doesn't say what you think it says. "Operator associativity" defines what happens if a sequence of the same operators is used one after another: whether the evaluator will evaluate the left operations first or the right. For example, in "8 - 4 - 2", subtraction is left associative so Perl evaluates the expression left to right. "8 - 4" is evaluated first making the expression "4 - 2 == 2" and not "8 - 2 == 6". This answers the question "Which minus operator will be evaluated first?" But our question is different: "Will a given operator evaluate its left-hand or right-hand argument first?" In other words, what if the code were `foo() - bar() - baz()`? Will foo() execute before bar(), or the reverse? Operator associativity has nothing to say about that. This is the same issue as `$i++ * $i` and `foo($i++, $i)`. I've looked through the docs, and it's not there. Perl doesn't define the evaluation order of subexpressions.	[reply] [d/l] [select]
Re^7: eval order of args to a sub by ikegami (Patriarch) on Jun 03, 2007 at 15:00 UTC
Re^8: eval order of args to a sub by shmem (Chancellor) on Jun 04, 2007 at 01:15 UTC
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Re^6: eval order of args to a sub by blazar (Canon) on May 30, 2007 at 21:34 UTC
I can confirm that is how it works on my system (ActivePerl 5.8.8 on WinXP). /me too. (Actually, that was in answer to otto.)	[reply]
Re^5: eval order of args to a sub by dewey (Pilgrim) on May 30, 2007 at 20:00 UTC
I see. Thanks. ~dewey	[reply]