PluggableSets allow the redefinition of hashing and equality by clients. This is in particular useful if the clients know about specific properties of the objects stored in the set which in turn can heavily improve the performance of sets and dictionaries.

Instance variables:
hashBlock <BlockContext> A one argument block used for hashing the elements.
equalBlock <BlockContext> A two argument block used for comparing the elements.

Example: Adding 1000 integer points in the range (0@0) to: (100@100) to a set.

| rnd set max pt |
set _ Set new: 1000.
rnd _ Random new.
max _ 100.
Time millisecondsToRun:[
1 to: 1000 do:[:i|
pt _ (rnd next * max) truncated @ (rnd next * max) truncated.
set add: pt.
].
].

The above is way slow since the default hashing function of points leads to an awful lot of collisions in the set. And now the same, with a somewhat different hash function:

| rnd set max pt |
set _ PluggableSet new: 1000.
set hashBlock:[:item| (item x bitShift: 16) + item y].
rnd _ Random new.
max _ 100.
Time millisecondsToRun:[
1 to: 1000 do:[:i|
pt _ (rnd next * max) truncated @ (rnd next * max) truncated.
set add: pt.
].
].

	copying
	copy postCopyBlocks

	private
	scanFor:

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	equalBlock Return the block used for comparing the elements in the receiver.
	equalBlock: Set a new equality block. The block must accept two arguments and return true if the argumets are considered equal, false otherwise
	hashBlock Return the block used for hashing the elements in the receiver.
	hashBlock: Set a new hash block. The block must accept one argument and return the hash value of the given argument.

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	copy Answer another instance just like the receiver. Subclasses typically override this method; they typically do not override shallowCopy.
	postCopyBlocks

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	scanFor: Scan the key array for the first slot containing either a nil (indicating an empty slot) or an element that matches anObject. Answer the index of that slot or zero if no slot is found. This method will be overridden in various subclasses that have different interpretations for matching elements.

	as yet unclassified	top
	integerSet