Stef,
#respondsTo: - no argument. More defensive programming (aka masked bugs).
Tests like this have their place, but are over-used in Squeak.
Using #submorphs *might* be easier to defend. Morphs were designed to be
usable in large numbers, and one might argue (playing Devil's Advocate here)
that lookups are cheaper than the additional gc load. An instance variable
could also cache stale information. Of course, for something that is accessed
frequently, an instance variable avoids the lookup and I agree that it is
cleaner and easier to read.
Bill
________________________________________
From: pharo-project-boun...@lists.gforge.inria.fr
[pharo-project-boun...@lists.gforge.inria.fr] On Behalf Of stephane ducasse
[stephane.duca...@free.fr]
Sent: Thursday, October 21, 2010 4:47 PM
To: Pharo Development
Subject: [Pharo-project] some patterns I would like to **kill**
Hi
I was reading Pluggable and friends
I identified some patterns.
The respondsTo plague
Examples:
color := self fillStyle asColor.
(self labelMorph respondsTo: #enabled:)
ifTrue: [self labelMorph enabled: self enabled].
(self labelMorph respondsTo: #interactionState:)
ifTrue: [self labelMorph interactionState: self
interactionState]
(self labelMorph respondsTo: #enabled:) ifTrue: [
self labelMorph enabled: aBoolean].
(self enabled not and: [self label isMorph and: [(self label respondsTo:
#enabled:) not]])
by construction a labelObject should be a morph and it should answer enabled:
and the case where this is not the case should be fixed.
Using submorphs to avoid one single inst var makes code quite ugly to read:
labelMorph
"Answer the actual label morph."
self hasSubmorphs ifFalse: [^nil].
self firstSubmorph hasSubmorphs ifFalse: [^nil].
^self firstSubmorph firstSubmorph
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