On 04.10.2011, at 17:58, Erlis Vidal wrote: > Hi all, > > I was looking at the implementation of some of the flow control methods and I > have a question with the method whileTrue. > > First of all, I can see two identical implementation in the classes > BlockClosure and BlockContext the implementation is this > > whileTrue: aBlock > "Ordinarily compiled in-line, and therefore not overridable. > This is in case the message is sent to other than a literal block. > Evaluate the argument, aBlock, as long as the value of the receiver is > true." > > ^ [self value] whileTrue: [aBlock value] > > I'm assuming here that there's another class Block I'm missing (something > like the literal block mentioned in the comment) which is the one that > contains the logic I was looking for. But I'm not able to find any other > whileTrue method in my image.
"Block" is just short for either BlockClosure or BlockContext. "Literal" blocks are those written directly with square brackets. If you store a block in a variable and pass that variable, the block would not be literal. > What's the difference between BlockClosure and BlockContext? BlockClosures are BlockContexts Done Right. If you wrote square brackets in older Squeak versions (3.x) you would get a BlockContext. In a current Squeak you get a BlockClosure. So since now we only have closures, the difference is only of historic interest. You can do some things with closures that you couldn't do with block contexts, e.g. recursive blocks: | fac | fac := nil. fac := [:n | n > 1 ifTrue: [n * (fac value: n - 1)] ifFalse: [1]]. fac value: 10 This would not have worked with contexts. - Bert -
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