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git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/steptalk/trunk@13642 72102866-910b-0410-8b05-ffd578937521
174 lines
4.7 KiB
Text
174 lines
4.7 KiB
Text
Smalltalk language extensions to NSObjects
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------------------------------------------
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Contents:
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1. Source
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2. Symbolic Selectors
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3. Iterators and cycles
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4. Exception handling
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1. Source
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---------
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Smalltalk script can be list of methods or just list of statements. List of
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statements is like single method without method name.
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List of methods
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---------------
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Source begins with '[|' (left square bracket) and is followed by optional list
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of script variables. Methods are separated by '!' and are encoles by ']' (right
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square bracket).
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Example without vars:
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[|
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main
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self other.
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^self
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!
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other
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Transcript showLine:'This is other'.
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!
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]
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Example with vars:
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[| :var1 :var2
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main
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"Your code here...".
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^self
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!
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other
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"Your code here...".
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^self
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!
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]
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Simple script (statements)
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--------------------------
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Simple script is just list of smalltalk statements. It is like contents of one
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method.
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Why source begins with '[|' and not just '['?
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---------------------------------------------
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Look at this example:
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[one two three]
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It has more meanings. It can be:
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- list of methods with one method named 'one'. 'two' is target object and
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'three' is a message.
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or
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- simple statement with block. 'one' is target object and 'two' and 'three'
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are messages.
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2. Symbolic selectors
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---------------------
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In StepTalk symbolic selectors are mapped to normal selectors.
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Comparison operators (NSObject)
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-------------------------------
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Symb. sel. Real sel.
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-------------------------------------
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= isEqual:
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== isSame:
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~= notEqual:
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~~ notSame:
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< isLessThan:
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> isGreatherThan:
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<= isLessOrEqualThan:
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>= isGreatherOrEqualThan:
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Target type Selector Argument Type Real Selector
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-----------------------------------------------------------------------
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NSArray @ NSNumber objectAtIndex:
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NSArray , any arrayByAddingObject:
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NSArray + any arrayByAddingObject:
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NSMutableArray += any addObject:
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NSMutableArray -= any removeObject:
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NSDictionary @ any objectForKey:
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NSUserDefaults @ any objectForKey:
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NSString , NSString stringByAppendingString:
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NSString / NSString stringByAppendingPathComponent:
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NSString @ NSNumber characterAtIndex:
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NSMutableString += NSString appendString:
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NSSet < NSSet isSubsetOfSet:
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NSMutableSet += any addObject:
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NSMutableSet -= any removeObject:
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NSDate - NSDate timeIntervalSinceDate:
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NSNumber +,-,*,/ NSNumber add:,subtract:,multiply:,divide:
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Special selectors to create objects from two NSNumbers
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Symb.sel. Real sel. Result Methods
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-------------------------------------------------------
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<> rangeWith: range location, length
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@ pointWith: point x, y
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@@ sizeWith: size width, height
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Examples:
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str := 'This is string.'.
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substr := str substringWithRange: (8 <> 3)
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range := str rangeOfString: 'str'.
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newRange := ( (range location) <> 6).
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3. Iterator and cycles
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----------------------
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Cycles
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------
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To create a cycle, you may use whileTrue: or whileFalse: on NSBlock
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conditionBlock whileTrue: toDoBlock.
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To use a sequence of numbers, you may use to:do: or to:step:do: on NSNumber
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min to: max do: block
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min to: max step: step do: block
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Array iterators
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---------------
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Following methods will iterate through all objects in receiver.
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Selector Description
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-------------------------------------------------------------------------------
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do: Evaluate block for each object in array and return last evaluated
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expression
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select: Create new array which will contain those objects from receiver,
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for which value of block was true
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reject: Create new array which will contain those objects from receiver,
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for which value of block was false
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collect: Create new array from block return values.
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detect: Return first object for which block evaluation result is true.
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Othervise return nil.
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4. Exception handling
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---------------------
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If you want to handle an exception, you may do so by using blocks. You send
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handler: message to guarded block.
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guardedBlock handler: handlerBlock.
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If exception occures in guarded block, then handler block is evaluated.
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