On 12 avr. 2011, at 23:47, Werner Kassens wrote:
> hi,
> i have a testsuite that is a subclass of TestCase with this method:
>
> testStupid
> |a|
> a :=#(1).
> self assert: a first isNumber .
> a :=a at:1 put: nil.
>
> if i run the test once, it succeeds, but but when i run it a second time it
> fails. this seems to be sligthly counterintuitive, or how do i have to
> understand it?
Interesting, I would never have guessed the test would be broken at first
sight. So maybe some people enlightened in the ways of the compiler can provide
a better explanation than me. Here is my guess:
#(1) is a special construct which creates a compile-time array. The
compile-time makes the trick: in short the array is more or less encoded
directly into the bytecodes of the method as a constant.
But modifying the array with #at:put: directly modifies the bytecodes in the
compiled method itself. So you create a side-effect directly into your method.
Am I the only one to find this a bit dangerous and not intuitive? Is it a
well-known behavior?
A correct way to fix that would be to use a dynamic array {1} or define a setUp
method which would initialize the array before each run.
--
Simon Denier
