Details
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New Feature
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Status: Closed
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Major
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Resolution: Won't Fix
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1.5.6, 1.6-beta-1
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None
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None
Description
The objective is that in any collection methods, the current index shall be available.
Refer to the discussion at:
http://www.nabble.com/Groovy-syntax--API-enhancement-td16796998.html#a16810531
The discussion was long and the relevant content are extracted as follow for easy of reading:
- support everyWithIndex, anyWithIndex, collectWithIndex, sumWithIndex etc. it's even better if the original every, any has an implicit variable/syntax for retrieving the index
e.g. [10,20].collectWithIndex { it,i -> it*(i+1) }= [ 10, 40 ]
- The problem here is that you are assuming that those methods (every,
any, collect, etc) are iterating over the collection with some
predetermined order, in sequence. Nothing in the semantics says it
should be so. They could be even be doing it in parallel.
- I am against all these withIndex methods... they are polluting the API
so much. I would like to have a more general solution, but I can't think
of any yet
- for 4..5, I did assume the collection is in sequence and is iteratable. It seems to me Groovy collections are usually in sequence by default. e.g. [] is ArrayList and [:].getClass() is LinkedHashMap, so in the majority of case, collection have order and have index. e.g. [] as Set is used, then the index will just be unavailable or always return -1.
- Can't you just modify the each/any/collect methods to test how many
parameters the closure takes? If the closure only takes one param
assume it is the item. If it takes two params, assume (item, index).
No?
- That's what we're already doing for some of the methods like each().
But it'd be nice to expand this approach to all methods for which it may apply.
Attachments
Issue Links
- relates to
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GROOVY-3797 Provide an index or counter for each/find/findAll/collect and friends by taking into accounts the arity of closures passed to them
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- Closed
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