I represent a set of elements that can be viewed from one of two perspectives: a set of associations, or a set of values that are externally named where the name can be any object that responds to =. The external name is referred to as the key.

	adding
	add: declare:from:

	enumerating
	associationsDo: collect: do: keysAndValuesDo: keysDo: select: valuesDo:

	printing
	flattenOnStream: printElementsOn: storeOn:

	private
	copy errorKeyNotFound errorValueNotFound keyAt: noCheckAdd: rehash scanFor: valueAtNewKey:put:atIndex:declareFrom:

	removing
	keysAndValuesRemove: remove: remove:ifAbsent: removeKey: removeKey:ifAbsent: removeUnreferencedKeys unreferencedKeys

	testing
	= hasContentsInExplorer includes: includesIdentity: includesKey: keyForIdentity: occurrencesOf:

	user interface
	inspect inspectFormsWithLabel: inspectWithLabel:

	accessing	top
	associationAt:
	associationAt:ifAbsent: Answer the association with the given key. If key is not found, return the result of evaluating aBlock.
	associationDeclareAt: Return an existing association, or create and return a new one. Needed as a single message by ImageSegment.prepareToBeSaved.
	at: Answer the value associated with the key.
	at:ifAbsent: Answer the value associated with the key or, if key isn't found, answer the result of evaluating aBlock.
	at:ifAbsentPut: Return the value at the given key. If key is not included in the receiver store the result of evaluating aBlock as new value.
	at:ifPresent: Lookup the given key in the receiver. If it is present, answer the value of evaluating the given block with the value associated with the key. Otherwise, answer nil.
	at:ifPresentAndInMemory: Lookup the given key in the receiver. If it is present, answer the value of evaluating the given block with the value associated with the key. Otherwise, answer nil.
	at:put: Set the value at key to be anObject. If key is not found, create a new entry for key and set is value to anObject. Answer anObject.
	keyAtIdentityValue: Answer the key that is the external name for the argument, value. If there is none, answer nil. Note: There can be multiple keys with the same value. Only one is returned.
	keyAtIdentityValue:ifAbsent: Answer the key that is the external name for the argument, value. If there is none, answer the result of evaluating exceptionBlock. Note: There can be multiple keys with the same value. Only one is returned.
	keyAtValue: Answer the key that is the external name for the argument, value. If there is none, answer nil.
	keyAtValue:ifAbsent: Answer the key that is the external name for the argument, value. If there is none, answer the result of evaluating exceptionBlock. : Use =, not ==, so stings like 'this' can be found. Note that MethodDictionary continues to use == so it will be fast.
	keys Answer a Set containing the receiver's keys.
	keysSortedSafely Answer a SortedCollection containing the receiver's keys.
	values Answer a Collection containing the receiver's values.

	adding	top
	add: Include newObject as one of the receiver's elements, but only if not already present. Answer newObject.
	declare:from: Add key to the receiver. If key already exists, do nothing. If aDictionary includes key, then remove it from aDictionary and use its association as the element of the receiver.

	enumerating	top
	associationsDo: Evaluate aBlock for each of the receiver's elements (key/value associations).
	collect: Evaluate aBlock with each of my values as the argument. Collect the resulting values into a collection that is like me. Answer with the new collection.
	do: Evaluate aBlock with each of the receiver's elements as the argument.
	keysAndValuesDo:
	keysDo: Evaluate aBlock for each of the receiver's keys.
	select: Evaluate aBlock with each of my values as the argument. Collect into a new dictionary, only those associations for which aBlock evaluates to true.
	valuesDo: Evaluate aBlock for each of the receiver's keys.

	printing	top
	flattenOnStream:
	printElementsOn:
	storeOn: Refer to the comment in Object|storeOn:.

	private	top
	copy Must copy the associations, or later store will effect both the original and the copy
	errorKeyNotFound
	errorValueNotFound
	keyAt: May be overridden by subclasses so that fixCollisions will work
	noCheckAdd: Must be defined separately for Dictionary because (self findElementOrNil:) expects a key, not an association. 9/7/96 tk
	rehash Smalltalk rehash.
	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.
	valueAtNewKey:put:atIndex:declareFrom: Support for coordinating class variable and global declarations with variables that have been put in Undeclared so as to redirect all references to the undeclared variable.

	removing	top
	keysAndValuesRemove: Removes all entries for which keyValueBlock returns true.
	remove: Remove oldObject from the receiver's elements. Answer oldObject unless no element is equal to oldObject, in which case, raise an error. ArrayedCollections cannot respond to this message.
	remove:ifAbsent: Remove oldObject from the receiver's elements. If several of the elements are equal to oldObject, only one is removed. If no element is equal to oldObject, answer the result of evaluating anExceptionBlock. Otherwise, answer the argument, oldObject. ArrayedCollections cannot respond to this message.
	removeKey: Remove key from the receiver. If key is not in the receiver, notify an error.
	removeKey:ifAbsent: Remove key (and its associated value) from the receiver. If key is not in the receiver, answer the result of evaluating aBlock. Otherwise, answer the value externally named by key.
	removeUnreferencedKeys Undeclared removeUnreferencedKeys
	unreferencedKeys TextConstants unreferencedKeys

	testing	top
	= Equal if it has my keys, is same size, and has the same corresponding value associated with each key.
	hasContentsInExplorer
	includes: Answer whether anObject is one of the receiver's elements.
	includesIdentity: Answer whether anObject is one of the values of the receiver. Contrast #includes: in which there is only an equality check, here there is an identity check
	includesKey: Answer whether the receiver has a key equal to the argument, key.
	keyForIdentity: If anObject is one of the values of the receive, return its key, else return nil. Contrast #keyAtValue: in which there is only an equality check, here there is an identity check
	occurrencesOf: Answer how many of the receiver's elements are equal to anObject.

	user interface	top
	inspect Open a DictionaryInspector on the receiver. Use basicInspect to get a normal (less useful) type of inspector.
	inspectFormsWithLabel: Open a Form Dictionary inspector on the receiver, with the given label.
	inspectWithLabel: Open a DictionaryInspector on the receiver. Use basicInspect to get a normal (less useful) type of inspector.

	instance creation	top
	newFrom: Answer an instance of me containing the same associations as aDict. Error if any key appears twice.