Shadowed variables [was: Re: animated gifs]
Dan Ingalls
Dan at SqueakLand.org
Tue Feb 22 22:10:18 UTC 2005
>On Tuesday 22 February 2005 12:31 am, Scott Wallace wrote:
>> Hi,
>>
>> Does anyone have any recent experience with using animated GIFs in Squeak?
>>
>> Theoretically animated-gif support arrived in Squeak 3.7. However, I
>> have not been able successfully to load any animated gif into any
>> 3.7- or 3.8-based version of Squeak. Whenever I try to "open" an
>> animated gif from a file-list, I always get an error. Does this
>> happen to anyone else?
>>
>> Any advice much appreciated!
>
>Remove the local 'offset' variable in AnimatedGIFReadWriter>>allImages; it's
>shadowing the instance variable.
Just a note about QA of releases. In the "old days", shadowing was considered an error, and one of the pre-release procedures was to recompile the whole system. Thus, this bug would have been caught.
If we are going to allow this kind of shadowing, then I suggest that there be a system test equivalent to recompiling the system and locating shadowed variables. They should be as much of a red flag as references to Undeclared.
- Dan
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