[Newbies] Re: error trap
On Sun, 13 Aug 2006 18:31:23 +0200, Damien Cassou wrote: Yes. And, into the other direction, even in good core methods one often finds things like ^ dict at: aKey ifAbsent: [nil] There seems to be a natural confusion between object value and block value. What's the problem with that ? The lack of understanding the expressive power of the software developer is the problem. Why always use a hammer? Because everything looks like nails? Yes, 'nil value' answers nil but 'nil' is not a block and #at:ifAbsent: waits for a block (the parameter is called aBlock). No, #at:ifAbsent: doesn't wait for an instance of BlockContext. Smalltalk is typeless and, if at all, only has *one* (the universal) type. It is shorter to write 'nil' directly I agree. And the compiler is not forced to emit code for a BlockContext and the VM is not forced to create a BlockContext only for throwing it away unused (unused in the sense that nil == [nil] value). It is like writing (x) versus (0+x) or (1*x). What is more problematic in my point of view is code like this: AbstractLauncherparameterAt: parName ifAbsent: aBlock Return the parameter named parName. Evaluate the block if parameter does not exist. ^self parameters at: parName asUppercase ifAbsent: [aBlock value] It may be me (still a beginner), but it looks equivalent to ^self parameters at: parName asUppercase ifAbsent: aBlock Yes, anObject == [anObject] value. which is faster and clearer in my opinion. Sure. /Klaus ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: error trap
On Mon, 14 Aug 2006 10:17:40 +0200, Damien Cassou [EMAIL PROTECTED] wrote: Klaus D. Witzel wrote: For an example try a printIt on ^ true ifTrue: #a ifFalse: [false ifTrue: #b ifFalse: #c] Again, a natural confusion between an object's value and a block's value. - argument of ifTrue: must be a block or variable - In VW, there is no Objectvalue method. But #value is implemented in Boolean and UndefinedObject. Is this Smalltalk-standard to have #value on Object ? Just scanned SmalltalkV2.sources and SqueakV1.sources: #value is not implemented by Object nor by UndefinedObject. /Klaus ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: error trap
On Fri, 11 Aug 2006 23:00:03 +0200, stéphane ducasse wrote: Klaus wrote: Yes. And, into the other direction, even in good core methods one often finds things like ^ dict at: aKey ifAbsent: [nil] this is much better. Why do you call failures in understanding things like this better, Stef? Whoever writes such statements, has no idea about an object's value versus a block's value and especially no idea about when and why execution of a block of code can and should be delayed (not to speak about performance impact). I would like to see caseOf:...removed from the system And replace it by what? Why would you limit the expressive power of the software developer, Stef? /Klaus stef ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: error trap
On Thu, 10 Aug 2006 17:27:09 +0200, Roel Wuyts wrote: Note: no need for the endEntry when using show: it does it already (see TranscriptStream#show: ) Use a 'manual' endEntry when you would use nextPutAll: or print: etc. on the Transcript (which most people do not use anyway). Right you are! But I'm writing on recycled web pages, those with notoriously small margin, therefore I tend to believe that people point to the methods mentioned (like #endEndtry) and curiously look for implementors and other good things in the same message category, the famous cmd-m followed by a cmd-b and/or cmd-m :p /Klaus ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: error trap
Hi Ron,
on Thu, 10 Aug 2006 17:02:11 +0200, you wrote:
From: Klaus D. Witzel
... You didn't inspectIt for verifying
No I didn't! The { } just looked so wrong and like C!
Yes, same for me when I saw that for the first time in Squeak. Never saw
that in Smalltalk/2.x (didn't look for it in VW).
But nowaday's I wonder how we have done it for so many decades without
handsome {expression. 'constant'. [block]} select: [:everything |
everything isAnObject].
/Klaus
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[Newbies] Re: error trap
On Wed, 09 Aug 2006 19:59:41 +0200, Brian Murphy-Dye wrote:
Ron, another crazy possibility comes to mind when reading your
excellent description: making each line it's own block.
{[10/0].
[2 raisedToInteger: 1/2].
[-5 raisedTo: 1.5]
} do: [:each | [each value] on: Exception do: [:ex | Transcript show:
ex; cr]].
Excellent, Brian. Why do you still write in the beginners list ;-)
...
Ah, now I can see why: Transcript endEntry is missing from the above :)
/joke
/Klaus
Brian.
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