Onionmixer: 정오표 수정

2014-05-09T09:20:55Z

정오표 수정

← Older revision		Revision as of 09:20, 9 May 2014
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	Notice that the method for next depends on the method implemented in the superclass (super next). The superclass's method checks to make certain that the sample space is not empty and then randomly selects an element. After determining the selected element, the subclass's method removes the element from data. The result of the remove: message is the argument, so that the result of the message next to a ~~SarnpleSpaceWithoutReplacement~~ is the selected element.		Notice that the method for next depends on the method implemented in the superclass (super next). The superclass's method checks to make certain that the sample space is not empty and then randomly selects an element. After determining the selected element, the subclass's method removes the element from data. The result of the remove: message is the argument, so that the result of the message next to a SampleSpaceWithoutReplacement is the selected element.


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	Another way to provide a deck of playing cards is illustrated in the description of example class CardDeck. The basic idea is to store a linear list of cards; next means supply the first card in the list. A card can be returned to the deck by placing it at the end or by inserting it at some random position. The linear list is made random by ~~shuftlling~~-that is, randomly ordering the cards.		Another way to provide a deck of playing cards is illustrated in the description of example class CardDeck. The basic idea is to store a linear list of cards; next means supply the first card in the list. A card can be returned to the deck by placing it at the end or by inserting it at some random position. The linear list is made random by shuffling-that is, randomly ordering the cards.


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	As long as there is no winner, each player with less than 21 points is given another card from the ~~flameCards~~. Before dealing a card to each eligible player, the dealer looks to see if there are any winners by testing the points for each player.		As long as there is no winner, each player with less than 21 points is given another card from the gameCards. Before dealing a card to each eligible player, the dealer looks to see if there are any winners by testing the points for each player.

	<syntaxhighlight lang="smalltalk">		<syntaxhighlight lang="smalltalk">
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	The condition for continuing to play is a block with two expressions. The first expression determines the winners, if any, The second expression tests to see if there are any winners yet (winners isEmpty) and, if not, if there are any more cards to deal out (~~flameCards~~ isEmpty not). If there are no winners and more cards, the game continues. The game consists of an enumeration of each player; each player takes another card (each take: gameCards next)only if the number of card points is less than 21 (each points < 21).		The condition for continuing to play is a block with two expressions. The first expression determines the winners, if any, The second expression tests to see if there are any winners yet (winners isEmpty) and, if not, if there are any more cards to deal out (gameCards isEmpty not). If there are no winners and more cards, the game continues. The game consists of an enumeration of each player; each player takes another card (each take: gameCards next)only if the number of card points is less than 21 (each points < 21).


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	While this solves the simplest version of the problem, we might also like to know some additional information, such as how many times each tile was visited. To record this information, we can use an instance of class Bag. The size of the Bag is the total number of steps the cockroach took; the size of the Bag when it is converted to a Set is the total number of distinct tiles touched by the cockroach. When this number reaches N'M, the problem is solved. The number of occurrences of each tile in the Bag is the same as the number of times the roach visited each tile.		While this solves the simplest version of the problem, we might also like to know some additional information, such as how many times each tile was visited. To record this information, we can use an instance of class Bag. The size of the Bag is the total number of steps the cockroach took; the size of the Bag when it is converted to a Set is the total number of distinct tiles touched by the cockroach. When this number reaches N*M, the problem is solved. The number of occurrences of each tile in the Bag is the same as the number of times the roach visited each tile.


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	A Tile refers to its row and column locations, each of which must be at least 1 and no larger than the width or length of the floor. Therefore, in addition to remembering its location, a Tile must remember the maximum floor space in which it can be placed. A Tile can be sent the message ~~neightborAt~~: aPoint in order to determine a Tile at one of the locations next to it. This new Tile must be at a location within the ~~boundarie~~~ of the floor.		A Tile refers to its row and column locations, each of which must be at least 1 and no larger than the width or length of the floor. Therefore, in addition to remembering its location, a Tile must remember the maximum floor space in which it can be placed. A Tile can be sent the message neighborAt: aPoint in order to determine a Tile at one of the locations next to it. This new Tile must be at a location within the boundaries of the floor.


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	class initialization		class initialization
	initialize		initialize
	"Create the collection of direction vectors and the ~~raondom~~ number generator."		"Create the collection of direction vectors and the random number generator."
	Directions ← OrderedCollection new: 9.		Directions ← OrderedCollection new: 9.
	(-1 to: 1) do: [ :x \| (-1 to: 1) do: [ :y \| Directions add: x@y]].		(-1 to: 1) do: [ :x \| (-1 to: 1) do: [ :y \| Directions add: x@y]].
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	\|<syntaxhighlight lang="smalltalk">		\|<syntaxhighlight lang="smalltalk">
	instance creation		instance creation
	left: ~~INode~~ right: rNode		left: lNode right: rNode
	"Create an instance of a Node with the arguments ~~INode~~ and rNode as the left and right subnodes, respectively."		"Create an instance of a Node with the arguments lNode and rNode as the left and right subnodes, respectively."
	\| newNode\|		\| newNode\|
	newNode ← self new.		newNode ← self new.
	newNode left: ~~INode~~.		newNode left: lNode.
	newNode right: rNode.		newNode right: rNode.
	↑newNode		↑newNode
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	===A Binary Word Tree===		===A Binary Word Tree===

	The definition of a Node, like that of a Link, is all structure without content. We have left the content of each Node to be specified by a subclass. Suppose we wish to use a kind of Node to store words represented as Strings. We call this class WordNode. An instance of WordNode is created by sending WordNode the message for:, if no subnodes are ~~specifled~~, or for:left:right: if the two subnodes are specified. So a WordNode illustrated as		The definition of a Node, like that of a Link, is all structure without content. We have left the content of each Node to be specified by a subclass. Suppose we wish to use a kind of Node to store words represented as Strings. We call this class WordNode. An instance of WordNode is created by sending WordNode the message for:, if no subnodes are specified, or for:left:right: if the two subnodes are specified. So a WordNode illustrated as

	[[image:Smalltalk80LanguageImplementation_11-2.png\|그림 11-2]]		[[image:Smalltalk80LanguageImplementation_11-2.png\|그림 11-2]]
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	for: aString		for: aString
	↑self new word: aString		↑self new word: aString
	for: aString left: ~~INode~~ right: rNode		for: aString left: lNode right: rNode
	\| newNode \|		\| newNode \|
	newNode ← super left: ~~INode~~ right: rNode.		newNode ← super left: lNode right: rNode.
	newNode word: aString.		newNode word: aString.
	~~↑newnode~~		↑newNode
	</syntaxhighlight>		</syntaxhighlight>
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Onionmixer: SMALLTALK80 Chapter 11 Three Examples that Use Collections 페이지 추가

2014-04-22T15:54:26Z

SMALLTALK80 Chapter 11 Three Examples that Use Collections 페이지 추가

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Smalltalk80LanguageImplementation:Chapter 11 - Revision history

Onionmixer: 정오표 수정

Onionmixer: SMALLTALK80 Chapter 11 Three Examples that Use Collections 페이지 추가