Re: [Pharo-users] is this valid smalltalk

[Roelof Wobben]

I already thought to use this flow. but I only wondered if I could use the ^false this way and appearently it is allowed. so I can begin with this one. The Pharo track is still hidden but I saw on the github page that in a short time it will be public with some 20 - 25 challenges. Roelof Op 4-4-2019 om 14:36 schreef Richard O'Keefe: For a change this is an exercism problem I know something about. I did look at the exercism web site, and did all the SML exercises, but could not find any for Smalltalk or Pharo. The exercise is in fact about using a stack.    stack <- empty    for each character of the string       if it is one of ( [ { push it on the stack       if it is one of ) ] }          if the stack is empty or the top element does not             correspond to this character, return false       if it is not one of ( ) [ ] { } just ignore it    return (the stack is empty) BOTH of the "return" constructs in this pseudo-code become ^ something in Smalltalk.  "Long returns", where "^" occurs inside a block, are well defined, very useful, and universally accepted in Smalltalk. There is no analogue of "^" for returning from a block. By the way, this has nothing to do with #do:.  It's about returning from the method through any number of blocks. For example, you will sometimes see code like    x := aDictionary at: aKey ifAbsent: [^false]. On Fri, 5 Apr 2019 at 00:16, Roelof Wobben <r.wob...@home.nl> wrote: Hello, For a challenge of Exercism I need to check if some parenthes and brackets are balanced. so for example ()  = true ([])  = true but (])  is not true because the bracket has no opening bracket. Now I wonder if I can premature end a #do:  like this collection do: [:element | (condition with element) ifFalse: [^false]] in pseudo code is this a valid way to end the do ? or is there a better way ? Roelof