Hi folks.
I have a bit of code I am attempting to expand and I am getting strange
behavior on a very simple change in structure.
I am parsing '2 * 3 / 2" and returning the product of the terms. Works
fine.
Here is the original code. it works as intended.
* result := pairs inject: first
into: [ :total :pair | |p|
p := pair reject:[:a | a class = OrderedCollection].
(p first = '*')
ifTrue: [total := (total * p last )]
ifFalse: [
(p last = 0)
ifTrue:[^NaNError]. "prevent divide by 0"
total := ( total / p last )]
] .*
However, If I make a very simple change to the internal logic by changing
the ifTrue: ifFalse: to two separate tests 'total' goes nil on the second
pass.
* result := pairs inject: first
into: [ :total :pair | |p|
p := pair reject:[:a | a class = OrderedCollection].
(p first = '*')
ifTrue: [total := (total * p last )] .
(p first = '/')
ifTrue: [
(p last = 0)
ifTrue:[^NaNError]. "prevent divide by 0"
total := ( total / p last )]
] .*
it blows up on the second pass as 'total' is Nil and the division throughs a
DNU. yet, |p| is populated with #('/' 2)
Thanks in advance
--
Sent from:
http://forum.world.st/Squeak-Beginners-f107673.html_______________________________________________
Beginners mailing list
[hidden email]
http://lists.squeakfoundation.org/mailman/listinfo/beginners
Locked
