> select: selectBlock thenCollect: collectBlock
>
> | newCollection |
> newCollection := self species new.
> self do: [:each | (selectBlock value: each) ifTrue: [newCollection add:
> (collectBlock value: each)]].
> ^newCollection
That code would also break Dictionary and Array.
I think the methods #select:thenCollect: and #collect:thenSelect:
should be removed:
- This is a low level optimization that the compiler (or JIT) should
optimize, not the developer.
- 'a select: b thenCollect: c' is longer to write than '(a select: b)
collect: c'. Furthermore it is not that obvious what it does. I have
seen several people being confused about it.
- This is just #select:thenCollect:, what about
#reject:thenCollect:select:thenInjectInto:? What about all subclasses
that require a new implementation (Array, Dictionary, ...) of such
methods.
If people really want to be able to combine enumerator methods for
higher efficiently the Collection hierarchy should be fixed. Having
external iterator objects like in C++ and Java is not that bad after
all:
result := aCollection iterator
select: [ :e | ... ];
collect: [ :e | ... ];
contents
The accessors #select:, #reject:, #collect: ... on the iterator object
would just iteratively create a new iteration block that is lazily
executed when the result is accessed with #contents, #size or #do:.
Cheers,
Lukas
--
Lukas Renggli
http://www.lukas-renggli.ch
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