Dynamic namespaces via exceptions
trygver at ifi.uio.no
Sat May 14 09:41:45 UTC 2005
In BabyUML, I am experimenting with a very dynamic namespace that is put on
the stack, that exists during the execution of a block, and that is visible
to all methods called directly or indirectly from the block.
It seems to work using the exeception mechanism, but I would appreciate
assistance to check if I am doing something ugly or dangerous.
The namespace class is called Map and is a subclass of Exception.
I create aMap with the desired contents and put it on the stack with:
[body statements] on: aMap do: [:ex | ].
Any method called from the body statements get hold of the map by this method:
| ctx map |
ctx := thisContext.
[ ctx := ctx findNextHandlerContextStarting.
ctx isNil or: [(map := ctx tempAt: 1) isKindOf: DNetMap]
] whileFalse: [ctx := ctx sender].
ifNil: [self error: 'No map found.'. nil]
Many thanks for any tips or guidance.
(If this works, it illustratesthe extreme power of Squeak)
Trygve Reenskaug mailto: trygver at ifi.uio.no
Morgedalsvn. 5A http://heim.ifi.uio.no/~trygver
N-0378 Oslo Tel: (+47) 22 49 57 27
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