On Wed, 7 Aug 2013, psea wrote:
Ok, i've got it. So in ST it's just not allowed assign to a block argument for some reason. Let's consider it a language feature. And it's ok,
It's a compiler bug. The compiler doesn't handle this case. - TempVariableNode >> #analyseClosure: returns if the receiver is a block argument without checking the preference. - BlockNode >> #postNumberingProcessTempsWithin:rootNode: only checks the temporaries, but not the arguments of the receiver. - Even if the above two are fixed, the temp index is still out of bounds, because removing arguments is not supported (see #removeTempNode:ifAbsent: and its sender), so the original temp for the argument will be kept.
different language - different rules. Thanks for pointing me on that! Now, I've turn off allowBlockArgumentAssignment property.
What's worried me is that in other languages I'm familiar with it's a normal thing to assign to a function argument (Scheme, C, Python, JavaScript).
Storing into a block or method argument is considered bad practice. Support for it is/was planned to be removed. Even though it can yield somewhat better performance, it's something you'll rarely see in Smalltalk code.
answer to your questions: Smalltalk vmVersion 'Squeak3.10.2 of 11 February 2010 [latest update: #9314]' SmalltalkImage current systemInformationString "ditto" 'Squeak4.3 latest update: #11860 Current Change Set: Unnamed1' Windows XP.
PS But you should agree with me that
makeAcc := [ :acc | [:n | acc:=acc+n. acc]]
looks a little bit better and concise than
makeAcc := [ :acc | | total | total:=acc. [:n | total:=total+n. total]]
There's no need to explicitly return 'total' from the inner block, because the assignment yields the same value:
makeAcc := [ :acc | | total | total := acc. [ :n | total := total + n ] ]
Levente
:-)
And thanks for the links.
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