6.134 Symbol

Defined in namespace Smalltalk

Category: Language-Implementation

My instances are unique throughout the Smalltalk system. My instances behave for the most part like strings, except that they print differently, and I guarantee that any two instances that have the same printed representation are in fact the same instance.

6.134.1 Symbol class: built ins		(class)
6.134.2 Symbol class: instance creation		(class)
6.134.3 Symbol class: symbol table		(class)
6.134.4 Symbol: basic		(instance)
6.134.5 Symbol: built ins		(instance)
6.134.6 Symbol: converting		(instance)
6.134.7 Symbol: misc		(instance)
6.134.8 Symbol: storing		(instance)
6.134.9 Symbol: testing		(instance)
6.134.10 Symbol: testing functionality		(instance)

6.134.1 Symbol class: built ins

intern: aString

Private - Same as 'aString asSymbol'

6.134.2 Symbol class: instance creation

internCharacter: aCharacter

Answer the one-character symbol associated to the given character.

new

This method should not be called for instances of this class.

new: size

This method should not be called for instances of this class.

with: element1

Answer a collection whose only element is element1

with: element1 with: element2

Answer a collection whose only elements are the parameters in the order they were passed

with: element1 with: element2 with: element3

Answer a collection whose only elements are the parameters in the order they were passed

with: element1 with: element2 with: element3 with: element4

Answer a collection whose only elements are the parameters in the order they were passed

with: element1 with: element2 with: element3 with: element4 with: element5

Answer a collection whose only elements are the parameters in the order they were passed

6.134.3 Symbol class: symbol table

hasInterned: aString ifTrue: aBlock

If aString has not been interned yet, answer false. Else, pass the interned version to aBlock and answer true. Note that this works because String>>#hash calculates the same hash value used by the VM when interning strings into the SymbolTable. Changing one of the hashing methods without changing the other will break this method.

isSymbolString: aString

Answer whether aString has already been interned. Note that this works because String>>#hash calculates the same hash value used by the VM when interning strings into the SymbolTable. Changing one of the hashing methods without changing the other will break this method.

rebuildTable

Rebuild the SymbolTable, thereby garbage-collecting unreferenced Symbols. While this process is done, preemption is disabled because it is not acceptable to leave the SymbolTable in a partially updated state. Note that this works because String>>#hash calculates the same hash value used by the VM when interning strings into the SymbolTable. Changing one of the hashing methods without changing the other will break this method.

6.134.4 Symbol: basic

deepCopy

Returns a deep copy of the receiver. As Symbols are identity objects, we actually return the receiver itself.

numArgs

Answer the number of arguments supported by the receiver, which is supposed to be a valid message name (#+, #not, #printOn:, #ifTrue:ifFalse:, etc.)

shallowCopy

Returns a deep copy of the receiver. As Symbols are identity objects, we actually return the receiver itself.

6.134.5 Symbol: built ins

= aSymbol

Answer whether the receiver and aSymbol are the same object

hash

Answer an hash value for the receiver. Symbols are optimized for speed

6.134.6 Symbol: converting

asString

Answer a String with the same characters as the receiver

asSymbol

But we are already a Symbol, and furthermore, Symbols are identity objects! So answer the receiver.

6.134.7 Symbol: misc

species

Answer `String'.

6.134.8 Symbol: storing

displayOn: aStream

Print a represention of the receiver on aStream. For most objects this is simply its #printOn: representation, but for strings and characters, superfluous dollars or extra pairs of quotes are stripped.

displayString

Answer a String representing the receiver. For most objects this is simply its #printString, but for strings and characters, superfluous dollars or extra pair of quotes are stripped.

printOn: aStream

Print a represention of the receiver on aStream.

6.134.9 Symbol: testing

isSimpleSymbol

Answer whether the receiver must be represented in quoted-string (e.g. #'abc-def') form.

6.134.10 Symbol: testing functionality

isString

Answer `false'.

isSymbol

Answer `true'.