Newbie Question: How does this work?
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Newbie Question: How does this work?
 
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Greetings:
I filed in the below code. When I ask '%6.2e' what class it is, it replies ByteString. '%6.2e' class => ByteString When I send a ByteString the #printf, it somehow knows to look in the FormatString class for this method. '%6.2e' printf: 412.343434 => '412.34' My question is, where is the place in the below code where this gets redirected? i.e., Where the printf method gets added to the ByteString path of available methods. Thanks for your help, Joe. Object subclass: #FormatDescriptor instanceVariableNames: 'flush width precision' classVariableNames: 'Flags Operators' poolDictionaries: '' category: 'Printf'! !FormatDescriptor methodsFor: 'rendering'! applyOperator: object self subclassResponsibility! ! !FormatDescriptor methodsFor: 'rendering' stamp: 'hjo 9/18/2011 00:31'! render: object | string | string := self applyOperator: object. self stringLength ~= 0 ifTrue: [ string := string copyFrom: 1 to: (self stringLength min: string size) ]. width == 0 ifTrue: [ ^ string ]. ^ (String new: width withAll: self padding) copyReplaceFrom: (self startIndexOfCopyReplaceWithStringSize: string size) to: (self stopIndexOfCopyReplaceWithStringSize: string size) with: string! ! !FormatDescriptor methodsFor: 'rendering' stamp: 'hjo 9/18/2011 00:31'! startIndexOfCopyReplaceWithStringSize: anInteger |start| flush == #leftFlush ifTrue: [start := 1]. flush == #rightFlush ifTrue: [start := width - anInteger + 1]. ^(start max: 1) ! ! !FormatDescriptor methodsFor: 'rendering' stamp: 'hjo 9/18/2011 00:31'! stopIndexOfCopyReplaceWithStringSize: anInteger | stop | flush == #leftFlush ifTrue: [stop := anInteger]. flush == #rightFlush ifTrue: [stop := width]. ^stop min: width! ! !FormatDescriptor methodsFor: 'private'! flush ^ flush! ! !FormatDescriptor methodsFor: 'private' stamp: 'mir 6/6/2000 23:58'! operator: char | myself | myself := (Smalltalk at: (Operators at: char)) newFrom: self. myself setOperator: char. ^ myself! ! !FormatDescriptor methodsFor: 'private'! padding ^ Character space! ! !FormatDescriptor methodsFor: 'private'! precision ^ precision! ! !FormatDescriptor methodsFor: 'private'! precision: anInteger precision := anInteger! ! !FormatDescriptor methodsFor: 'private'! setOperator: char! ! !FormatDescriptor methodsFor: 'private'! stringLength ^ precision isNil ifTrue: [0] ifFalse: [precision]! ! !FormatDescriptor methodsFor: 'private'! width ^ width! ! !FormatDescriptor methodsFor: 'private'! width: anInteger width := anInteger! ! !FormatDescriptor methodsFor: 'initialize-release'! initialize flush := #rightFlush. width := 0! ! !FormatDescriptor methodsFor: 'scanning'! leftFlush flush := #leftFlush! ! !FormatDescriptor methodsFor: 'scanning'! radix ^ (NumberFormatDescriptor newFrom: self) radix! ! !FormatDescriptor methodsFor: 'scanning'! rightFlush flush := #rightFlush! ! !FormatDescriptor methodsFor: 'scanning'! space ^ (NumberFormatDescriptor newFrom: self) space! ! !FormatDescriptor methodsFor: 'scanning'! zero ^ (NumberFormatDescriptor newFrom: self) zero! ! !FormatDescriptor methodsFor: 'printing'! printOn: aStream aStream nextPut: $%. flush == #leftFlush ifTrue: [aStream nextPut: $-]! ! !FormatDescriptor methodsFor: 'printing'! printWidthOn: aStream width ~= 0 ifTrue: [width printOn: aStream]. precision isNil ifFalse: [aStream nextPut: $.. precision printOn: aStream]! ! "-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- "! FormatDescriptor class instanceVariableNames: ''! !FormatDescriptor class methodsFor: 'class initialization' stamp: 'mir 6/7/2000 00:21'! initialize "FormatDescriptor initialize" Operators := Dictionary new. Operators at: $p put: #PrintStringFormatDescriptor. Operators at: $c put: #CharacterFormatDescriptor. Operators at: $s put: #StringFormatDescriptor. #($d $o $u $x $X) do: [:operator | Operators at: operator put: #NumberFormatDescriptor]. #($e $E $f $g $G) do: [:operator | Operators at: operator put: #FloatFormatDescriptor]. Flags := Dictionary new. Flags at: $- put: #leftFlush. Flags at: $+ put: #rightFlush. Flags at: $ put: #space. Flags at: $# put: #radix. Flags at: $0 put: #zero. ! ! !FormatDescriptor class methodsFor: 'instance creation'! new ^ super new initialize! ! !FormatDescriptor class methodsFor: 'instance creation'! newFrom: desc | myself | myself := self new. myself perform: desc flush. myself width: desc width. myself precision: desc precision. ^ myself! ! !FormatDescriptor class methodsFor: 'instance creation'! scanFrom: stream | desc | desc := self new. [Flags includesKey: stream peek] whileTrue: [desc := desc perform: (Flags at: stream next)]. stream peek isDigit ifTrue: [desc width: (Integer readFrom: stream)]. stream peek == $. ifTrue: [stream next. desc precision: (Integer readFrom: stream)]. stream peek == $l ifTrue: [stream next]. desc := desc operator: stream next. ^ desc! ! FormatDescriptor subclass: #CharacterFormatDescriptor instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !CharacterFormatDescriptor methodsFor: 'rendering'! applyOperator: object ^ String with: object asCharacter! ! !CharacterFormatDescriptor methodsFor: 'printing'! printOn: aStream super printOn: aStream. self printWidthOn: aStream. aStream nextPut: $c! ! Object subclass: #FormatString instanceVariableNames: 'format string composedString' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !FormatString commentStamp: 'mir 6/7/2000 00:14' prior: 0! Format description syntax: %{flags}{width}{precision}{long}<operator> flags - left flush + right flush space non-negative number are preceeded by a blank # display integer with a radix indicator (0=octal, 0x=hex, float have .) 0 0 is used as left padding character for numbers width minimum field width (rest is padded) .precision maximum field width or trailing digits long ignored operator c display object as character d display as integer e,E float in scientific notation f display as float g,G display as f or e,E using least amount of space o display as octal value s display as string u display as unsigned x,X display as hex value ! !FormatString methodsFor: 'printf'! << object "Render object according to next format descriptor in format. Append it to string" "Format description syntax: %{flags}{width}{precision}{long}<operator> flags - left flush + right flush space non-negative number are preceeded by a blank # display integer with a radix indicator (0=octal, 0x=hex, float have .) 0 0 is used as left padding character for numbers width minimum field width (rest is padded) .precision maximum field width or trailing digits long ignored operator c display object as character d display as integer e,E float in scientific notation f display as float g,G display as f or e,E using least amount of space o display as octal value s display as string u display as unsigned x,X display as hex value " composedString nextPutAll: string next. composedString nextPutAll: (format next render: object). format atEnd ifTrue: [format reset. composedString nextPutAll: string next. string reset]. ^composedString contents! ! !FormatString methodsFor: 'printf' stamp: 'hjo 9/17/2011 23:59'! printf: arguments "inst var string holds all text contained in the formatstring. %f blabla %d" "inst var format is a stream of FormatDescriptors" self reset. arguments asArgumentArrayForFormatString do: [:object | "put any text from the formatstring into composedstring" composedString nextPutAll: string next. "get next FormatDescriptor from format and render object as specified" format atEnd ifFalse: [composedString nextPutAll: (format next render: object)]]. "any remainder is string, if so append to composedString" string atEnd ifFalse: [composedString nextPutAll: string next]. ^self stringWithReset.! ! !FormatString methodsFor: 'printf'! string ^composedString contents! ! !FormatString methodsFor: 'printf' stamp: 'hjo 9/17/2011 23:59'! stringWithReset | result | result := self string. self reset. ^result! ! !FormatString methodsFor: 'initialize-release' stamp: 'hjo 9/18/2011 00:05'! collectFormatDescriptorsAndStrings: formatStream | done | format := ReadWriteStream on: (Array new: 10). string := ReadWriteStream on: (Array new: 10). done := false. [ done ] whileFalse: [ "copy actual formatstrings to format" string nextPut: (self scanStringFrom: formatStream). (done := formatStream atEnd) ifFalse: [ "copy any nonformating text to string" format nextPut: (FormatDescriptor scanFrom: formatStream) ] ]. self reset! ! !FormatString methodsFor: 'initialize-release' stamp: 'hjo 9/18/2011 00:05'! setFormat: aString | formatStream | "copy actual formatstrings to format" "copy any nonformating text to string" composedString := (String new: 20) writeStream. formatStream := ((aString copyReplaceAll: '\n' with: (String with: Character cr)) copyReplaceAll: '\t' with: (String with: Character tab)) readStream. self collectFormatDescriptorsAndStrings: formatStream! ! !FormatString methodsFor: 'private'! reset format reset. string reset. composedString reset! ! !FormatString methodsFor: 'private' stamp: 'hjo 9/18/2011 00:00'! scanStringFrom: aStream | newString | newString := (String new: 40) writeStream. [aStream atEnd] whileFalse: [| next | next := aStream next. next == $% ifTrue: [^newString contents]. next == $\ ifTrue: [next := aStream next. next == $n ifTrue: [next := Character cr]. next == $t ifTrue: [next := Character tab]]. newString nextPut: next]. ^newString contents! ! "-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- "! FormatString class instanceVariableNames: ''! !FormatString class methodsFor: 'examples' stamp: 'mir 6/7/2000 00:12'! examples self inform: ('Here is a string "%s".' printf: 'hello world'). self inform: ('Here is a string "%s" and another shortened "%-14.7s".' printf: #('hello world' 'hello world')). self inform: ('Here is a number "%d".' printf: 42). self inform: ('Here is a string "%07.7d".' printf: 42). self inform: ('Here is a number "%e".' printf: 42.0). self inform: ('Here is a float "%e" and an integer "%d".' printf: #(42.0 42)). self inform: ('Here is a string "%013.5e".' printf: 42.1234567). self inform: ('Here is a %s string "%s" and the same shortened "%-14.7s" with left flush.\nThe new line has a number "%e" and a 0-padded limited precision one "%013.5e".' printf: ((Array with: 'long' with: 'hello world' with: 'hello world' with: 42.0) copyWith: 42.1234567)).! ! TestCase subclass: #FormatStringTest instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:41'! testManyArguments self assert: 'Here is a long string "hello world" and the same shortened "hello w " with left flush. The new line has a number "42.0" and a 0-padded limited precision one "0000042.12345".' equals: ('Here is a %s string "%s" and the same shortened "%-14.7s" with left flush.\nThe new line has a number "%e" and a 0-padded limited precision one "%013.5e".' printf: ((Array with: 'long' with: 'hello world' with: 'hello world' with: 42.0) copyWith: 42.1234567)).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:41'! testOneExponent self assert: 'Here is a number "42.0".' equals: ('Here is a number "%e".' printf: 42.0).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:41'! testOneExponentAndOneInteger self assert: 'Here is a float "42.0" and an integer "42".' equals: ('Here is a float "%e" and an integer "%d".' printf: #(42.0 42)).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:41'! testOneExponentWithLength self assert: 'Here is a string "0000042.12345".' equals: ('Here is a string "%013.5e".' printf: 42.1234567).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:40'! testOneInteger self assert: 'Here is a number "42".' equals: ('Here is a number "%d".' printf: 42).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:40'! testOneIntegerWithLength self assert: 'Here is a string "0000042".' equals: ('Here is a string "%07.7d".' printf: 42).! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:40'! testOneString self assert: 'Here is a string "hello world".' equals: ('Here is a string "%s".' printf: 'hello world')! ! !FormatStringTest methodsFor: 'as yet unclassified' stamp: 'hjo 9/17/2011 23:40'! testOneStringWithLength self assert: 'Here is a string "hello world" and another shortened "hello w ".' equals: ('Here is a string "%s" and another shortened "%-14.7s".' printf: #('hello world' 'hello world'))! ! FormatDescriptor subclass: #NumberFormatDescriptor instanceVariableNames: 'operator padding radix space' classVariableNames: 'Base Radix' poolDictionaries: '' category: 'Printf'! !NumberFormatDescriptor methodsFor: 'rendering' stamp: 'mir 6/6/2000 23:56'! applyOperator: object "Character and Number are the only valid classes" | number string | object isNil ifTrue: [^'-']. "object isInteger ifFalse: [self halt]. " number := object asInteger. string := number printStringBase: self base. radix ifTrue: [string := self radixString , string]. (space and: [operator == $d and: [number < 0]]) ifTrue: [string := ' ' , string]. ^ (width ~= 0 and: [string size > self stringLength]) ifTrue: [String new: width withAll: $*] ifFalse: [string]! ! !NumberFormatDescriptor methodsFor: 'private'! base ^ Base at: operator! ! !NumberFormatDescriptor methodsFor: 'private'! padding ^ padding! ! !NumberFormatDescriptor methodsFor: 'private'! radixString ^ Radix at: operator! ! !NumberFormatDescriptor methodsFor: 'private'! setOperator: char operator := char! ! !NumberFormatDescriptor methodsFor: 'private'! setPadding: paddingChar padding := paddingChar! ! !NumberFormatDescriptor methodsFor: 'private'! stringLength ^precision isNil ifTrue: [SmallInteger maxVal] ifFalse: [precision]! ! !NumberFormatDescriptor methodsFor: 'initialize-release'! initialize super initialize. padding := $ . radix := false. space := false! ! !NumberFormatDescriptor methodsFor: 'printing'! printOn: aStream super printOn: aStream. padding == $0 ifTrue: [aStream nextPut: $0]. radix ifTrue: [aStream nextPut: $#]. space ifTrue: [aStream nextPut: $ ]. self printWidthOn: aStream. aStream nextPut: operator! ! !NumberFormatDescriptor methodsFor: 'scanning'! radix radix := true! ! !NumberFormatDescriptor methodsFor: 'scanning'! space space := true! ! !NumberFormatDescriptor methodsFor: 'scanning'! zero padding := $0! ! "-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- "! NumberFormatDescriptor class instanceVariableNames: ''! !NumberFormatDescriptor class methodsFor: 'class initialization'! initialize "NumberFormatDescriptor initialize" Base := Dictionary new. Base at: $d put: 10. Base at: $o put: 8. Base at: $u put: 10. Base at: $x put: 16. Base at: $X put: 16. Radix := Dictionary new. Radix at: $d put: ''. Radix at: $o put: '0'. Radix at: $u put: ''. Radix at: $x put: '0x'. Radix at: $X put: '0X'.! ! !NumberFormatDescriptor class methodsFor: 'instance creation'! newFrom: desc desc class == self ifTrue: [^ desc]. ^ (super newFrom: desc) setPadding: desc padding! ! NumberFormatDescriptor subclass: #FloatFormatDescriptor instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !FloatFormatDescriptor methodsFor: 'rendering' stamp: 'hjo 9/18/2011 00:47'! applyOperator: object "Number is the only valid class" | string | string := self zeroPaddedStringOfBase10ForFloat: object asFloat. string := string copyFrom: 1 to: ((string indexOf: $.) + (precision == 0 ifTrue: [-1] ifFalse: [self precision]) min: string size). (space and: [object asFloat >= 0]) ifTrue: [string := ' ' , string]. ^(width ~= 0 and: [string size > width]) ifTrue: [String new: width withAll: $*] ifFalse: [string]! ! !FloatFormatDescriptor methodsFor: 'rendering' stamp: 'hjo 9/18/2011 00:45'! zeroPaddedStringOfBase10ForFloat: aFloat | stream | stream := String new writeStream. aFloat printOn: stream base: 10. stream next: self precision-1 put: $0. ^stream contents. ! ! !FloatFormatDescriptor methodsFor: 'private' stamp: 'mir 6/7/2000 00:01'! digits ^ width == 0 ifTrue: [7] ifFalse: [width]! ! !FloatFormatDescriptor methodsFor: 'private'! precision ^ precision isNil ifTrue: [1] ifFalse: [precision]! ! !FloatFormatDescriptor methodsFor: 'private'! stringLength ^ width! ! FormatDescriptor subclass: #StringFormatDescriptor instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !StringFormatDescriptor methodsFor: 'rendering'! applyOperator: object ^ object! ! !StringFormatDescriptor methodsFor: 'printing'! printOn: aStream super printOn: aStream. self printWidthOn: aStream. aStream nextPut: $s! ! StringFormatDescriptor subclass: #PrintStringFormatDescriptor instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Printf'! !PrintStringFormatDescriptor methodsFor: 'rendering'! applyOperator: object ^ object printLeanString! ! !PrintStringFormatDescriptor methodsFor: 'printing'! printOn: aStream aStream nextPut: $%. flush == #leftFlush ifTrue: [aStream nextPut: $-]. self printWidthOn: aStream. aStream nextPut: $p! ! FormatDescriptor initialize! NumberFormatDescriptor initialize! |
Re: Newbie Question: How does this work?
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On 12-10-08 6:13 PM, Joseph J Alotta wrote:
> '%6.2e' printf: 412.343434 I loaded in the code you added in Squeak 4.3, executed the above, and got "MessageNotUnderstood: ByteString>>printf:". I then loaded in Printf from squeaksource.com/Printf and it worked. Monticello added some extra methods to various classes in the image. Don't look at FormatString>>printf: Look at String>>printf:, which is a superclass of ByteString. The protocol list has printf with an * before it - *printf. The Monticello package added some extra methods to the String class. Chris |
Re: Newbie Question: How does this work?
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In reply to this post by Joseph Alotta
Hi Joe,
Thank you for asking interesting questions and staying involved. One way to find this out for yourself is to run this code to step through what is happening (highlighting the two lines and hitting the PrintIt key combo):
self halt. '123%s456' printf: ('s'). You'll find that the class ByteString also now has a #printf: method inherited from String class. So, the ByteString class knows how to convert itself to a FormatString if it sees a #printf: method.
printf: arguments ^ self asFormatString printf: arguments The ' * ' in *printf method category name is a visual clue that a load has added it to the default String class. - Darius _______________
On Mon, Oct 8, 2012 at 3:13 PM, Joseph J Alotta <[hidden email]> wrote: Greetings:
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Re: Newbie Question: How does this work?
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In reply to this post by Joseph Alotta
Thanks for you help.
I see that String has a #printf and the protocol is *printf, and when the printf: method executes it looks everywhere for the FormatString class which is added to the end by the Printf package. So the question is how did the *printf protocols get added to String? It is not some magic by Monticello, because I did not use Monticello, I just filein-ed the code. So where in the code does it install the *printf methods to String? Sincerely, Joe. On Oct 9, 2012, at 7:00 AM, [hidden email] wrote: > On 12-10-08 6:13 PM, Joseph J Alotta wrote: >> '%6.2e' printf: 412.343434 > I loaded in the code you added in Squeak 4.3, executed the above, and > got "MessageNotUnderstood: ByteString>>printf:". I then loaded in Printf > from squeaksource.com/Printf and it worked. > > Monticello added some extra methods to various classes in the image. > Don't look at FormatString>>printf: Look at String>>printf:, which is a > superclass of ByteString. The protocol list has printf with an * before > it - *printf. The Monticello package added some extra methods to the > String class. > > Chris > > > Thank you for asking interesting questions and staying involved. > > One way to find this out for yourself is to run this code to step through > what is happening (highlighting the two lines and hitting the PrintIt key > combo): > self halt. > '123%s456' printf: ('s'). > > You'll find that the class ByteString also now has a #printf:method > inherited from String class. So, the ByteString class knows how to > convert itself to a FormatString if it sees a #printf: method. > printf: arguments > ^ self asFormatString printf: arguments > > The ' * ' in *printf method category name is a visual clue that a load has > added it to the default String class. |
Re: Newbie Question: How does this work?
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On 9 October 2012 16:08, Joseph J Alotta <[hidden email]> wrote:
> Thanks for you help. > > I see that String has a #printf and the protocol is *printf, and when the printf: method executes it looks everywhere for the FormatString class which is added to the end by the Printf package. > > So the question is how did the *printf protocols get added to String? It is not some magic by Monticello, because I did not use > Monticello, I just filein-ed the code. > > So where in the code does it install the *printf methods to String? The original code (in what's called "chunk format") was incomplete. If it had been complete (like the Printf Chris Cunnington's mentioned) you'd have seen something like this: !String methodsFor: '*printf'! printf: arguments ^ self asFormatString printf: arguments! ! In Monticello these chunks are instead represented by MCDefinition subclasses. frank > Sincerely, > > Joe. > > > > > > On Oct 9, 2012, at 7:00 AM, [hidden email] wrote: > >> On 12-10-08 6:13 PM, Joseph J Alotta wrote: >>> '%6.2e' printf: 412.343434 >> I loaded in the code you added in Squeak 4.3, executed the above, and >> got "MessageNotUnderstood: ByteString>>printf:". I then loaded in Printf >> from squeaksource.com/Printf and it worked. >> >> Monticello added some extra methods to various classes in the image. >> Don't look at FormatString>>printf: Look at String>>printf:, which is a >> superclass of ByteString. The protocol list has printf with an * before >> it - *printf. The Monticello package added some extra methods to the >> String class. >> >> Chris >> >> >> Thank you for asking interesting questions and staying involved. >> >> One way to find this out for yourself is to run this code to step through >> what is happening (highlighting the two lines and hitting the PrintIt key >> combo): >> self halt. >> '123%s456' printf: ('s'). >> >> You'll find that the class ByteString also now has a #printf:method >> inherited from String class. So, the ByteString class knows how to >> convert itself to a FormatString if it sees a #printf: method. >> printf: arguments >> ^ self asFormatString printf: arguments >> >> The ' * ' in *printf method category name is a visual clue that a load has >> added it to the default String class. > > |
Re: Newbie Question: How does this work?
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In reply to this post by Joseph Alotta
I know I can make changes directly to String and add a method. But I was wondering if I can
add a method to String and still keep the code in my Package. (I've made my own package/category called JJA that contains all the object that pertain to my program.) So is there a way to create a method in my own category for a class in another category? > Message: 4 > Date: Tue, 9 Oct 2012 16:16:59 +0100 > From: Frank Shearar <[hidden email]> > Subject: Re: [squeak-dev] Re: Newbie Question: How does this work? > To: The general-purpose Squeak developers list > <[hidden email]> > Message-ID: > <CAJbhyRH3WgsMDdYWMvnkdBF770kV=nqOOyxz1ysYrk=[hidden email]> > Content-Type: text/plain; charset=ISO-8859-1 > > On 9 October 2012 16:08, Joseph J Alotta <[hidden email]> wrote: >> Thanks for you help. >> >> I see that String has a #printf and the protocol is *printf, and when the printf: method executes it looks everywhere for the FormatString class which is added to the end by the Printf package. >> >> So the question is how did the *printf protocols get added to String? It is not some magic by Monticello, because I did not use >> Monticello, I just filein-ed the code. >> >> So where in the code does it install the *printf methods to String? > > The original code (in what's called "chunk format") was incomplete. If > it had been complete (like the Printf Chris Cunnington's mentioned) > you'd have seen something like this: > > !String methodsFor: '*printf'! > printf: arguments > ^ self asFormatString printf: arguments! ! > > In Monticello these chunks are instead represented by MCDefinition subclasses. > > frank |
Re: Newbie Question: How does this work?
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On 12-10-10 12:07 PM, Joseph J Alotta wrote:
> I know I can make changes directly to String and add a method. But I was wondering if I can > add a method to String and still keep the code in my Package. (I've made my own package/category called JJA > that contains all the object that pertain to my program.) > > So is there a way to create a method in my own category for a class in another category? > > > > > >> Message: 4 >> Date: Tue, 9 Oct 2012 16:16:59 +0100 >> From: Frank Shearar <[hidden email]> >> Subject: Re: [squeak-dev] Re: Newbie Question: How does this work? >> To: The general-purpose Squeak developers list >> <[hidden email]> >> Message-ID: >> <CAJbhyRH3WgsMDdYWMvnkdBF770kV=nqOOyxz1ysYrk=[hidden email]> >> Content-Type: text/plain; charset=ISO-8859-1 >> >> On 9 October 2012 16:08, Joseph J Alotta <[hidden email]> wrote: >>> Thanks for you help. >>> >>> I see that String has a #printf and the protocol is *printf, and when the printf: method executes it looks everywhere for the FormatString class which is added to the end by the Printf package. >>> >>> So the question is how did the *printf protocols get added to String? It is not some magic by Monticello, because I did not use >>> Monticello, I just filein-ed the code. >>> >>> So where in the code does it install the *printf methods to String? >> The original code (in what's called "chunk format") was incomplete. If >> it had been complete (like the Printf Chris Cunnington's mentioned) >> you'd have seen something like this: >> >> !String methodsFor: '*printf'! >> printf: arguments >> ^ self asFormatString printf: arguments! ! >> >> In Monticello these chunks are instead represented by MCDefinition subclasses. >> >> frank > left) at "--all--". Select "add category". Select "new". Type "*jja" and accept. Drag your method into that protocol category. Chris |
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