My instances add instance-specific behavior to various class-describing objects in the system. This typically includes messages for initializing class variables and instance creation messages particular to a class. There is only one instance of a particular Metaclass, namely the class which is being described. A Metaclass shares the class variables of its instance.

[Subtle] In general, the superclass hierarchy for metaclasses parallels that for classes. Thus,
Integer superclass == Number, and
Integer class superclass == Number class.
However there is a singularity at Object. Here the class hierarchy terminates, but the metaclass hierarchy must wrap around to Class, since ALL metaclasses are subclasses of Class. Thus,
Object superclass == nil, and
Object class superclass == Class.

[Subtle detail] A class is know by name to an environment. Typically this is the SystemDictionary named Smalltalk. If we ever make lightweight classes that are not in Smalltalk, they must be in some environment. Specifically, the code that sets 'wasPresent' in name:inEnvironment:subclassOf:instanceVariableNames:variable:words:pointers:classVariableNames:poolDictionaries:category:comment:changed: must continue to work.

	class hierarchy
	addSubclass: removeSubclass: subclasses subclassesDo: subclassesDoGently:

	compiling
	acceptsLoggingOfCompilation possibleVariablesFor:continuedFrom: scopeHas:ifTrue: wantsChangeSetLogging wantsRecompilationProgressReported

	copying
	copy veryDeepCopyWith:

	enumerating
	allInstancesDo: allInstancesEverywhereDo:

	fileIn/Out
	definitionST80 definitionST80: fileOutInitializerOn: fileOutOn:moveSource:toFile: fileOutOn:moveSource:toFile:initializing: nonTrivial objectForDataStream: storeDataOn:

	initialize-release
	adoptInstance:from: instanceVariableNames:

	instance creation
	new

	instance variables
	addInstVarName: removeInstVarName:

	pool variables
	classPool

	private
	replaceObsoleteInstanceWith:

	testing
	canZapMethodDictionary isObsolete

	instance creation

	accessing	top
	allInstances Answer a collection of all current instances of the receiver.
	environment Return the environment in which the receiver is visible
	isMeta
	isSystemDefined Answer false if I am a UniClass (an instance-specific lightweight class)
	name Answer a String that is the name of the receiver, either 'Metaclass' or the name of the receiver's class followed by ' class'.
	soleInstance The receiver has only one instance. Answer it.
	theNonMetaClass Sent to a class or metaclass, always return the class

	class hierarchy	top
	addSubclass: Do nothing.
	removeSubclass: Do nothing.
	subclasses Answer the receiver's subclasses.
	subclassesDo: Evaluate aBlock for each of the receiver's immediate subclasses.
	subclassesDoGently: Evaluate aBlock for each of the receiver's immediate subclasses.

	compiling	top
	acceptsLoggingOfCompilation Answer whether the receiver's method submisions and class defintions should be logged to the changes file and to the current change set. The metaclass follows the rule of the class itself. 6/18/96 sw
	possibleVariablesFor:continuedFrom:
	scopeHas:ifTrue: If the argument name is a variable known to the receiver, then evaluate the second argument, assocBlock.
	wantsChangeSetLogging Answer whether code submitted for the receiver should be remembered by the changeSet mechanism.The metaclass follows the rule of the class itself. 7/12/96 sw
	wantsRecompilationProgressReported The metaclass follows the rule of the class itself.

	copying	top
	copy Make a copy of the receiver without a list of subclasses. Share the reference to the sole instance.
	veryDeepCopyWith: Return self. Must be created, not copied. Do not record me.

	enumerating	top
	allInstancesDo: There should be only one
	allInstancesEverywhereDo: There should be only one

	fileIn/Out	top
	definitionST80 Refer to the comment in ClassDescription|definition.
	definitionST80: Refer to the comment in ClassDescription|definition.
	fileOutInitializerOn:
	fileOutOn:moveSource:toFile: File a description of the receiver on aFileStream. If the boolean argument, moveSource, is true, then set the trailing bytes to the position of aFileStream and to fileIndex in order to indicate where to find the source code.
	fileOutOn:moveSource:toFile:initializing:
	nonTrivial Answer whether the receiver has any methods or instance variables.
	objectForDataStream: I am about to be written on an object file. Write a reference to a class in Smalltalk instead.
	storeDataOn: I don't get stored. Use a DiskProxy

	initialize-release	top
	adoptInstance:from: Recreate any existing instances of the argument, oldClass, as instances of the receiver, which is a newly changed class. Permute variables as necessary.
	instanceVariableNames: Declare additional named variables for my instance.

	instance creation	top
	new The receiver can only have one instance. Create it or complain that one already exists.

	instance variables	top
	addInstVarName: Add the argument, aString, as one of the receiver's instance variables.
	removeInstVarName: Remove the argument, aString, as one of the receiver's instance variables.

	pool variables	top
	classPool Answer the dictionary of class variables.

	private	top
	replaceObsoleteInstanceWith:

	testing	top
	canZapMethodDictionary Return true if it is safe to zap the method dictionary on #obsolete
	isObsolete Return true if the receiver is obsolete

	anti-corruption	top
	isScarySelector: Return true if newbieSelector is already a part of Metaclass protocol.

instance creation

top