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Update smalltalk.html.markdown

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Jigyasa Grover 2015-10-04 22:44:20 +05:30
parent 40489d4352
commit 5bf5f12686
1 changed files with 127 additions and 125 deletions
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smalltalk.html.markdown
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@ -51,9 +51,8 @@ Transcript cr. "carriage return / l
Transcript endEntry. "flush the output buffer"
```
"************************************************************************
* Assignment: *
************************************************************************"
##Assignment:
```
| x y |
x _ 4. "assignment (Squeak) <-"
x := 5. "assignment"
@ -69,10 +68,10 @@ y := x copy. "copy object"
y := x shallowCopy. "copy object (not overridden)"
y := x deepCopy. "copy object and instance vars"
y := x veryDeepCopy. "complete tree copy using a dictionary"
```
"************************************************************************
* Constants: *
************************************************************************"
##Constants:
```
| b |
b := true. "true constant"
b := false. "false constant"
@ -90,9 +89,10 @@ x := #aSymbol. "symbol constants"
x := #(3 2 1). "array constants"
x := #('abc' 2 $a). "mixing of types allowed"
"************************************************************************
* Booleans: *
************************************************************************"
```
## Booleans:
```
| b x y |
x := 1. y := 2.
b := (x = y). "equals"
@ -128,9 +128,10 @@ b := x isNumber. "test if object is n
b := $A isUppercase. "test if upper case character"
b := $A isLowercase. "test if lower case character"
"************************************************************************
* Arithmetic expressions: *
************************************************************************"
```
## Arithmetic expressions:
```
| x |
x := 6 + 3. "addition"
x := 6 - 3. "subtraction"
@ -185,9 +186,10 @@ x := Float nan. "not-a-number"
x := Random new next; yourself. x next. "random number stream (0.0 to 1.0)
x := 100 atRandom. "quick random number"
"************************************************************************
* Bitwise Manipulation: *
************************************************************************"
```
##Bitwise Manipulation:
```
| b x |
x := 16rFF bitAnd: 16r0F. "and bits"
x := 16rF0 bitOr: 16r0F. "or bits"
@ -201,9 +203,10 @@ b := 16rFF allMask: 16r0F. "test if all bits se
b := 16rFF anyMask: 16r0F. "test if any bits set in mask set in receiver"
b := 16rFF noMask: 16r0F. "test if all bits set in mask clear in receiver"
"************************************************************************
* Conversion: *
************************************************************************"
```
## Conversion:
```
| x |
x := 3.99 asInteger. "convert number to integer (truncates in Squeak)"
x := 3.99 asFraction. "convert number to fraction"
@ -216,40 +219,39 @@ x := 15 radix: 16. "convert to string i
x := 15 printStringBase: 16.
x := 15 storeStringBase: 16.
"************************************************************************
* Blocks: *
* - blocks are objects and may be assigned to a variable *
* - value is last expression evaluated unless explicit return *
* - blocks may be nested *
* - specification [ arguments | | localvars | expressions ] *
* - Squeak does not currently support localvars in blocks *
* - max of three arguments allowed *
* - ^expression terminates block & method (exits all nested blocks) *
* - blocks intended for long term storage should not contain ^ *
************************************************************************"
```
## Blocks:
- blocks are objects and may be assigned to a variable
- value is last expression evaluated unless explicit return
- blocks may be nested
- specification [ arguments | | localvars | expressions ]
- Squeak does not currently support localvars in blocks
- max of three arguments allowed
- `^`expression terminates block & method (exits all nested blocks)
- blocks intended for long term storage should not contain `^`
```
| x y z |
x := [ y := 1. z := 2. ]. x value. "simple block usage"
x := [ :argOne :argTwo | argOne, ' and ' , argTwo.]. "set up block with argument passing"
Transcript show: (x value: 'First' value: 'Second'); cr. "use block with argument passing"
"x := [ | z | z := 1.]. localvars not available in squeak blocks"
"x := [ | z | z := 1.]. *** localvars not available in squeak blocks"
```
"************************************************************************
* Method calls: *
* - unary methods are messages with no arguments *
* - binary methods *
* - keyword methods are messages with selectors including colons *
* *
* standard categories/protocols: *
* - initialize-release (methods called for new instance) *
* - accessing (get/set methods) *
* - testing (boolean tests - is) *
* - comparing (boolean tests with parameter *
* - displaying (gui related methods) *
* - printing (methods for printing) *
* - updating (receive notification of changes) *
* - private (methods private to class) *
* - instance-creation (class methods for creating instance) *
************************************************************************"
## Method calls:
- unary methods are messages with no arguments
- binary methods
- keyword methods are messages with selectors including colons standard categories/protocols: - initialize-release (methods called for new instance)
- accessing (get/set methods)
- testing (boolean tests - is)
- comparing (boolean tests with parameter
- displaying (gui related methods)
- printing (methods for printing)
- updating (receive notification of changes)
- private (methods private to class)
- instance-creation (class methods for creating instance)
```
| x |
x := 2 sqrt. "unary message"
x := 2 raisedTo: 10. "keyword message"
@ -261,10 +263,10 @@ Transcript "Cascading - send mu
show: 'world';
cr.
x := 3 + 2; * 100. "result=300. Sends message to same receiver (3)"
```
"************************************************************************
* Conditional Statements: *
************************************************************************"
##Conditional Statements:
```
| x |
x > 10 ifTrue: [Transcript show: 'ifTrue'; cr]. "if then"
x > 10 ifFalse: [Transcript show: 'ifFalse'; cr]. "if else"
@ -293,10 +295,10 @@ switch at: $A put: [Transcript show: 'Case A'; cr].
switch at: $B put: [Transcript show: 'Case B'; cr].
switch at: $C put: [Transcript show: 'Case C'; cr].
result := (switch at: $B) value.
```
"************************************************************************
* Iteration statements: *
************************************************************************"
## Iteration statements:
```
| x y |
x := 4. y := 1.
[x > 0] whileTrue: [x := x - 1. y := y * 2]. "while true loop"
@ -305,10 +307,10 @@ x timesRepeat: [y := y * 2]. "times repear loop (
1 to: x do: [:a | y := y * 2]. "for loop"
1 to: x by: 2 do: [:a | y := y / 2]. "for loop with specified increment"
#(5 4 3) do: [:a | x := x + a]. "iterate over array elements"
```
"************************************************************************
* Character: *
************************************************************************"
## Character:
```
| x y |
x := $A. "character assignment"
y := x isLowercase. "test if lower case"
@ -326,9 +328,10 @@ y := x asString. "convert to string"
b := $A <= $B. "comparison"
y := $A max: $B.
"************************************************************************
* Symbol: *
************************************************************************"
```
## Symbol:
```
| b x y |
x := #Hello. "symbol assignment"
y := 'String', 'Concatenation'. "symbol concatenation (result is string)"
@ -347,10 +350,10 @@ y := x asOrderedCollection. "convert symbol to o
y := x asSortedCollection. "convert symbol to sorted collection"
y := x asBag. "convert symbol to bag collection"
y := x asSet. "convert symbol to set collection"
```
"************************************************************************
* String: *
************************************************************************"
## String:
```
| b x y |
x := 'This is a string'. "string assignment"
x := 'String', 'Concatenation'. "string concatenation"
@ -377,12 +380,12 @@ y := x asSortedCollection. "convert string to s
y := x asBag. "convert string to bag collection"
y := x asSet. "convert string to set collection"
y := x shuffled. "randomly shuffle string"
```
"************************************************************************
* Array: Fixed length collection *
* ByteArray: Array limited to byte elements (0-255) *
* WordArray: Array limited to word elements (0-2^32) *
************************************************************************"
## Array: Fixed length collection
## ByteArray: Array limited to byte elements (0-255)
## WordArray: Array limited to word elements (0-2^32)
```
| b x y sum max |
x := #(4 3 2 1). "constant array"
x := Array with: 5 with: 4 with: 3 with: 2. "create array with up to 4 elements"
@ -419,10 +422,10 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* OrderedCollection: acts like an expandable array *
************************************************************************"
##OrderedCollection: acts like an expandable array
```
| b x y sum max |
x := OrderedCollection with: 4 with: 3 with: 2 with: 1. "create collection with up to 4 elements"
x := OrderedCollection new. "allocate collection"
@ -462,11 +465,10 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* SortedCollection: like OrderedCollection except order of elements *
* determined by sorting criteria *
************************************************************************"
## SortedCollection: like OrderedCollection except order of elements determined by sorting criteria
```
| b x y sum max |
x := SortedCollection with: 4 with: 3 with: 2 with: 1. "create collection with up to 4 elements"
x := SortedCollection new. "allocate collection"
@ -505,11 +507,10 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* Bag: like OrderedCollection except elements are in no *
* particular order *
************************************************************************"
## Bag: like OrderedCollection except elements are in no particular order
```
| b x y sum max |
x := Bag with: 4 with: 3 with: 2 with: 1. "create collection with up to 4 elements"
x := Bag new. "allocate collection"
@ -537,11 +538,11 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* Set: like Bag except duplicates not allowed *
* IdentitySet: uses identity test (== rather than =) *
************************************************************************"
## Set: like Bag except duplicates not allowed
## IdentitySet: uses identity test (== rather than =)
```
| b x y sum max |
x := Set with: 4 with: 3 with: 2 with: 1. "create collection with up to 4 elements"
x := Set new. "allocate collection"
@ -568,10 +569,10 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* Interval: *
************************************************************************"
## Interval:
```
| b x y sum max |
x := Interval from: 5 to: 10. "create interval object"
x := 5 to: 10.
@ -597,19 +598,19 @@ y := x asOrderedCollection. "convert to ordered
y := x asSortedCollection. "convert to sorted collection"
y := x asBag. "convert to bag collection"
y := x asSet. "convert to set collection"
```
"************************************************************************
* Associations: *
************************************************************************"
##Associations:
```
| x y |
x := #myVar->'hello'.
y := x key.
y := x value.
```
"************************************************************************
* Dictionary: *
* IdentityDictionary: uses identity test (== rather than =) *
************************************************************************"
## Dictionary:
## IdentityDictionary: uses identity test (== rather than =)
```
| b x y |
x := Dictionary new. "allocate collection"
x add: #a->4; add: #b->3; add: #c->1; add: #d->2; yourself. "add element to collection"
@ -670,10 +671,10 @@ CMRDictionary associationsDo: [:aKeyValue | "another iterator fo
Transcript show: aKeyValue printString; cr].
Smalltalk removeKey: #CMRGlobal ifAbsent: []. "remove entry from Smalltalk dictionary"
Smalltalk removeKey: #CMRDictionary ifAbsent: []. "remove user dictionary from Smalltalk dictionary"
```
"************************************************************************
* Internal Stream: *
************************************************************************"
## Internal Stream:
```
| b x ios |
ios := ReadStream on: 'Hello read stream'.
ios := ReadStream on: 'Hello read stream' from: 1 to: 5.
@ -700,10 +701,10 @@ x := ios next.
x := ios peek.
x := ios contents.
b := ios atEnd.
```
"************************************************************************
* FileStream: *
************************************************************************"
## FileStream:
```
| b x ios |
ios := FileStream newFileNamed: 'ios.txt'.
ios nextPut: $H; cr.
@ -721,10 +722,10 @@ x := ios next.
x := ios peek.
b := ios atEnd.
ios close.
```
"************************************************************************
* Date: *
************************************************************************"
## Date:
```
| x y |
x := Date today. "create date for today"
x := Date dateAndTimeNow. "create date from current time/date"
@ -755,10 +756,10 @@ y := x subtractDays: 10. "subtract days to da
y := x subtractDate: (Date today). "subtract date (result in days)"
y := x printFormat: #(2 1 3 $/ 1 1). "print formatted date"
b := (x <= Date today). "comparison"
```
"************************************************************************
* Time: *
************************************************************************"
## Time:
```
| x y |
x := Time now. "create time from current time"
x := Time dateAndTimeNow. "create time from current time/date"
@ -775,10 +776,10 @@ y := x asSeconds. "convert time to sec
x := Time millisecondsToRun: [ "timing facility"
1 to: 1000 do: [:index | y := 3.14 * index]].
b := (x <= Time now). "comparison"
```
"************************************************************************
* Point: *
************************************************************************"
## Point:
```
| x y |
x := 200@100. "obtain a new point"
y := x x. "x coordinate"
@ -800,15 +801,15 @@ x := 200@100 // 3@4. "divide points"
x := 200@100 max: 50@200. "max x and y"
x := 200@100 min: 50@200. "min x and y"
x := 20@5 dotProduct: 10@2. "sum of product (x1*x2 + y1*y2)"
```
"************************************************************************
* Rectangle: *
************************************************************************"
## Rectangle:
```
Rectangle fromUser.
```
"************************************************************************
* Pen: *
************************************************************************"
## Pen:
```
| myPen |
Display restoreAfter: [
Display fillWhite.
@ -832,10 +833,10 @@ Display width. "get display width"
Display height. "get display height"
].
```
"************************************************************************
* Dynamic Message Calling/Compiling: *
************************************************************************"
## Dynamic Message Calling/Compiling:
```
| receiver message result argument keyword1 keyword2 argument1 argument2 |
"unary message"
receiver := 5.
@ -868,10 +869,10 @@ result := (Message
setSelector: (keyword1, keyword2) asSymbol
arguments: (Array with: argument1 with: argument2))
sentTo: receiver.
```
"************************************************************************
* class/meta-class: *
************************************************************************"
## Class/Meta-class:
```
| b x |
x := String name. "class name"
x := String category. "organization category"
@ -901,10 +902,10 @@ b := String isBits. "true if index insta
b := String isBytes. "true if index instance vars contain bytes"
b := String isWords. true if index instance vars contain words"
Object withAllSubclasses size. "get total number of class entries"
```
"************************************************************************
* debuging: *
************************************************************************"
## Debuging:
```
| a b x |
x yourself. "returns receiver"
String browse. "browse specified class"
@ -924,14 +925,15 @@ x primitiveFailed. "system primitive fa
a := 'A1'. b := 'B2'. a become: b. "switch two objects"
Transcript show: a, b; cr.
```
"************************************************************************
* Misc. *
************************************************************************"
## Misc
```
| x |
"Smalltalk condenseChanges." "compress the change file"
x := FillInTheBlank request: 'Prompt Me'. "prompt user for input"
Utilities openCommandKeyHelp
```