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by James Robertson.
Original Post: Replacing Values in Collections
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Both the post title AND content made me think about another form of the same. When you want to replace all of the existing elements in a collection given a transform expressed by a block. It is interesting to look at some use cases of collect:. Often there is an initial collection. And then there's a transformation or two that takes place using collect: Each results in a new collection being created. Often though, they're just transient. For most cases, the difference between creating a new collection for the transformation and reusing the old ones, is academic. In the case of large collections, it can become a serious issue.
Whether it's just the academic or the performance that motivates you, you soon decide to exten your image with something like:
SequenceableCollection>>modify: aBlock
1 to: self size do: [:i | self at: i put: (aBlock value: (self at: i))]
You can of course do the analog for Dictionaries. With this method you can now modify a collection in place:
customerNames := #('james_bond' 'me_too' 'him_and_me').
customerNames modify: [:each | each tokensBasedOn: %_].
customerNames modify: [:each | each modify: [:name | name raiseFirst]]
It's not a very good example, but it works to illustrate. I found soon after doing modify:, that I wanted a with:modify:, analagous to the with:collect: methods that have been added to the system. For some actual good examples of (with:)modify:, one can load and look at NumericCollections, which uses these to make possible something like:
#(1 2 3 4 5 6) += 5
The NumericCollections version is actually named (with:)numericModify: to separate it from our own BaseExtensions package.
David demonstrated a code pattern inspired by a simple pattern in C. In this case, I'd like to C(++) come up with the pattern that emulates this one.
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