Hi damien
I was looking at the following code
Sequenceable>>flatCollect: aBlock
"Evaluate aBlock for each of the receiver's elements and answer the
list of all resulting values flatten one level. Assumes that aBlock
returns some kind
of collection for each element. Equivalent to the lisp's mapcan"
"original written by a. Kuhn and released under MIT"
| stream |
self isEmpty ifTrue: [^self copy ].
stream := (self species new: self size) writeStream.
self do: [ :each |
stream nextPutAll: (aBlock value: each) ].
^stream contents
and if we send the message to a set we get a problem because
WriteStream>>nextPut: anObject
"Primitive. Insert the argument at the next position in the Stream
represented by the receiver. Fail if the collection of this stream is
not an
Array or a String. Fail if the stream is positioned at its end, or if
the
position is out of bounds in the collection. Fail if the argument is
not
of the right type for the collection. Optional. See Object
documentation
whatIsAPrimitive."
<primitive: 66>
((collection class == ByteString) and: [
anObject isCharacter and:[anObject isOctetCharacter not]])
ifTrue: [
collection := (WideString from: collection).
^self nextPut: anObject.
].
position >= writeLimit
ifTrue: [^ self pastEndPut: anObject]
ifFalse:
[position := position + 1.
^collection at: position put: anObject]
so the solution is to specialize flatCollect: on Set
flatCollect: aBlock
"Evaluate aBlock for each of the receiver's elements and answer the
union of all resulting values. Assumes that aBlock returns some kind
of collection for each element."
| set |
self isEmpty ifTrue: [^self copy].
set := Set new.
self do: [ :each |
set addAll: (aBlock value: each) ].
^set
Now I was wondering if there is way to avoid that.
Stef
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