On 11/18/2011 01:42 PM, Jimmy Johnson wrote:
I don't know where else to turn for help so...if one of you experts
would have the time to look at this project and see if an obvious
problem jumps out, and let me know, I would really appreciate it.
The project is to write a rational number class and include
units/dimensions (meters/length). The system works fine in Squeak
SmallTalk, but fails in gnu SmallTalk. I'm guessing it has something
to do with my use of deepClone.
Yes, that's correct. deepCopy is not standardized, but it traditionally
made only a 1-level deep copy.
The better way to do it in GNU Smalltalk is to use "copy" and add
postCopy methods such as
Unitable>>postCopy
unitsImp := unitsImp collect: [ :each | each copy ]
DimensionedRational>>postCopy
unitsImp := unitsImp copy
etc.
From a quick read of the code I'm not sure where you actually need
deeper copies, so the above is likely incomplete or incorrect.
As an aside, I suggest that you replace all uses of "self length" with
simply "1" (why is length special?) and merge the Constants and
Dimensionable classes. Also, the Comparable class is exactly the same
as Magnitude, except that it doesn't test the precondition that the
classes are the same. In general such preconditions hamper the usage of
polymorphism, so they're not used in Smalltalk.
Paolo
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