"

 COPYRIGHT (c) 1991 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

"{ Package: 'stx:libbasic' }"

nil subclass:#Autoload

	instanceVariableNames:''

	classVariableNames:'LazyLoading AutoloadFailedSignal LoadedClasses'

	poolDictionaries:''

	category:'Kernel-Classes'

!

!Autoload class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1991 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    In memory limited systems (as my 8Mb 386 is) all seldom-used classes are made

    subclasses of this class. 

    Autoload catches all messages and files-In the corresponding code

    when first used. 

    Then the caught message is resent to the (now existing) class.

    Class files are searched along the searchPath (see Smalltalk),

    and any of binary-classFile, byteCode-classFile or sourceFile are

    loaded, whichever is found first. For binaries to be loaded,

    these must be found in the 'bin' directory. Sources must be found

    in the 'source' directory.

    (Usually, Autoload classes finds the source file and loads that one).

    When started, the patches startup script arranges for the abbreviation

    file 'include/abbrev.stc' to be read and installs autoload stubs for

    all classes listed in that file, which do not exists already.

    The abbreviation file is maintained by the production environment

    and updated by makefile rules - therefore, it should not be edited

    manually.

    Late addition: above comment is no longer true - I have made now almost

    all Demos & Goodies be autoloaded ... even for big systems.

    [class variables:]

	LazyLoading             <Boolean>       if true, the loaded classes 

						methods will NOT be compiled at 

						autoload time, but instead when 

						first called. This allows for a 

						faster load. However, expect short 

						pauses later when the methods are

						first executed.

	AutoloadFailedSignal    <Signal>        signal raised if an autoloaded 

						classes source is not available.

	LoadedClasses           <Collection>    set of classes that heve been

						autoloaded (for later unload)

    [see also:]

	Smalltalk

    [author:]

	Claus Gittinger

"

! !

!Autoload class methodsFor:'initialization'!

initialize

    "initialize the failure-signal"

    AutoloadFailedSignal isNil ifTrue:[

	LazyLoading := false.

	AutoloadFailedSignal := Object errorSignal newSignalMayProceed:true.

	AutoloadFailedSignal nameClass:self message:#autoloadFailedSignal.

	AutoloadFailedSignal notifierString:'autoload failed'.

	self class changeClassTo:AutoloadMetaclass.

	self setSuperclass:nil.

	ObjectMemory flushCaches.

    ].

    self ~~ Autoload ifTrue:[

	^ self doesNotUnderstand:(Message selector:#initialize)

    ].

    "Modified: / 20.5.1997 / 19:06:25 / cg"

    "Modified: / 3.8.1999 / 14:23:30 / stefan"

! !

!Autoload class methodsFor:'Signal constants'!

autoloadFailedSignal

    "return the signal raised when an autoload fails"

    ^ AutoloadFailedSignal

! !

!Autoload class methodsFor:'adding/removing autoloaded classes'!

addClass:aClassName

    "given a name, install a corresponding autoload class stub for it.

     Return the (autoload-) stubClass or nil, if no new class was created."

    ^ self addClass:aClassName inCategory:'autoloaded-Classes'

    "

     Autoload addClass:'Clock'

    "

    "Modified: 24.4.1996 / 19:54:16 / cg"

!

addClass:aClassName inCategory:aCategory

    "given a name, install a corresponding autoload class stub for it.

     Return the (autoload-) stubClass or nil, if no new class was created."

    |nameSymbol cls|

    nameSymbol := aClassName asSymbol.

    (Smalltalk at:nameSymbol) isNil ifTrue:[

	cls := Autoload 

		subclass:nameSymbol

		instanceVariableNames:''

		classVariableNames:''

		poolDictionaries:''

		category:aCategory.

    ].

    ^ cls

    "

     Autoload addClass:'Clock' inCategory:'autoloaded-Demos'

    "

    "Modified: 24.4.1996 / 19:54:20 / cg"

!

removeClass:aClass

    "remove a class from the list of loaded classes"

    LoadedClasses remove:aClass ifAbsent:[]

    "Modified: 24.4.1996 / 19:54:35 / cg"

! !

!Autoload class methodsFor:'fileout'!

basicFileOutDefinitionOn:aStream withNameSpace:forceNameSpace withPackage:withPackage

    "print an expression to define myself on aStream.

     Since autoloaded classes dont know their real definition, simply

     output some comment string making things clear in the browser."

    |myName fileName nm package|

    (self == Autoload) ifTrue:[

	^ super 

	    basicFileOutDefinitionOn:aStream 

	    withNameSpace:forceNameSpace

	    withPackage:withPackage

    ].

    myName := self name.

    aStream nextPutAll:'"' ; nextPutLine:'Notice from Autoload:'; cr;

	    spaces:4; nextPutLine:myName , ' is not yet loaded.'; cr.

    aStream nextPutAll:'to load, execute: '.

    aStream cr; cr; spaces:4; nextPutLine:myName  , ' autoload'.

    aStream cr; nextPutLine:'or use the browsers load-function (in the class menu)'.

    aStream nextPutLine:'(double-click on the class will also load it).'.

    "

     the following is simply informative ...

     actually, its a hack & kludge - there ought to be a method for this

     in Smalltalk 

     (knowing the details of loading here is no good coding style)

    "

    fileName := Smalltalk fileNameForClass:myName.

    (ObjectFileLoader notNil and:[Smalltalk loadBinaries]) ifTrue:[

	(nm := Smalltalk libraryFileNameOfClass:myName) notNil ifTrue:[

	    nm := nm , ' (a classLibrary, possibly including more classes)'

	] ifFalse:[

	    nm := Smalltalk getBinaryFileName:(fileName , '.so').

	    nm isNil ifTrue:[

		nm := Smalltalk getBinaryFileName:(fileName , '.o')

	    ].

	    nm notNil ifTrue:[

		nm := nm , ' (a classBinary)'

	    ]

	].

    ].

    nm isNil ifTrue:[

	package := self package.

	package notNil ifTrue:[

	    nm := Smalltalk getSourceFileName:((package copyReplaceAll:$: with:$/) , '/' , fileName , '.st').

	].

	nm isNil ifTrue:[

	    nm := Smalltalk getSourceFileName:(fileName , '.st').

	].

    ].

    nm notNil ifTrue:[

	aStream cr; nextPutLine:'When accessed, ' , myName , ' will automatically be loaded'.

	aStream nextPutLine:'from: '; spaces:4; nextPutAll:nm.

	nm asFilename isSymbolicLink ifTrue:[

	    aStream cr; cr.

	    aStream nextPutLine:'which is a link to: '; spaces:4; 

		    nextPutAll:(nm asFilename linkInfo path).

	]

    ] ifFalse:[

	package := self package.

	(Smalltalk at:#SourceCodeManager) notNil ifTrue:[

	    aStream nextPutAll:'

When accessed, I''ll ask the sourceCodeManager to load the code 

from ''' , fileName , '.st'' in the ''' , package , ''' package.'.

	] ifFalse:[

	    aStream nextPutAll:'

When accessed, I''ll search for a file named 

''' , fileName , '.st'' in the ''' , package , ''' package.

Packages are tried along the packagePath, which is:

' , ((Smalltalk packagePath asStringCollection collect:[:each| '   ' , each]) asStringWith:Character cr). 

	]

    ].

    aStream cr; nextPutAll:'"'.

    "Created: / 5.1.1997 / 14:31:33 / cg"

    "Modified: / 6.6.1999 / 15:17:30 / cg"

! !

!Autoload class methodsFor:'lazy compilation'!

compileLazy

    "return the lazy loading flag - if on, fileIn is much faster,

     but pauses are to be expected later, since methods are compiled

     when first executed."

    ^ LazyLoading

!

compileLazy:aBoolean

    "turn on/off lazy loading - if on, fileIn is much faster,

     but pauses are to be expected later, since methods are compiled

     when first executed.

     If you like it, add a line to your startup file."

    LazyLoading := aBoolean

! !

!Autoload class methodsFor:'loading'!

autoload

    "use this to force loading

     - it is defined a noop in all non-autoloading classes"

    |mySelf myName myNameSpace newClass oldMeta project prevMode 

     package|

    mySelf := self.

    myName := self name asSymbol.

    myNameSpace := self nameSpace.

    "/ recheck - in case my class somehow came into the system

    "/ (by loading a binary...)

    (newClass := Smalltalk at:myName) ~~ self ifTrue:[

    ].

    "load it"

    (Object infoPrinting and:[Smalltalk silentLoading ~~ true]) ifTrue:[

    ].

    [

"/

"/ no- do not do this; it may lead to trouble ...

"/        ClassCategoryReader sourceMode:#reference.

    ] valueOnUnwindDo:[

    ].

    "did it work ?"

    newClass := Smalltalk at:myName.

    Smalltalk at:myName put:mySelf.   "will be undone by become:"

    "no - report the error"

    newClass isNil ifTrue:[

    ].

    newClass setPackage:package.

    "/

    "/ autoloaded classes get their package from the revision (if present)

    "/ this only happens with autoloaded sourceFiles which have no package

    "/ info encoded. (binary classes have it)

    "/ If there is no such information, give it my package (if I have one)

    "/

"/    newClass setPackageFromRevision.

"/

"/    newPackage := newClass package.

"/    (newPackage isNil or:[newPackage = 'no package']) ifTrue:[

"/        (package notNil and:[package ~= 'no package']) ifTrue:[

"/            newClass setPackage:package.

"/        ].

"/    ].

    LoadedClasses isNil ifTrue:[

    ].

    LoadedClasses add:newClass.

    "wow - it worked. now the big trick ..."

"/    newClass class setSoleInstance:self.   "/ will be undone by become ...

    oldMeta := self class.

"/ self setName:(self name , ' (auto)').

    self becomeSameAs:newClass.

    oldMeta becomeSameAs:newClass class.

    ObjectMemory flushCaches.

    LoadedClasses rehash.

    newClass initializeWithAllPrivateClasses.

    newClass postAutoload.

    Smalltalk changed:#classDefinition with:newClass.

    ^ newClass

    "Modified: / 5.3.1999 / 12:59:13 / cg"

! !

!Autoload class methodsFor:'message catching'!

basicNew

    "catch basicNew - load the class and send it to the real one"

    ^ self doesNotUnderstand:(Message selector:#basicNew)

    "Modified: 24.4.1996 / 19:53:10 / cg"

!

basicNew:arg

    "catch basicNew: - load the class and send it to the real one"

    ^ self doesNotUnderstand:(Message selector:#basicNew: with:arg)

    "Modified: 24.4.1996 / 19:53:16 / cg"

!

comment

    "return the classes comment.

     Autoloaded classes have no comment; but I myself have one"

    (self == Autoload) ifTrue:[^ super comment].

    ^ 'not yet loaded'

!

doesNotUnderstand:aMessage

    "caught a message; load the class and retry the message"

    |newClass|

    self ~~ Autoload ifTrue:[

	newClass := self autoload.

	newClass notNil ifTrue:[

	    ^ aMessage sendTo:newClass

	]

    ].

    ^ super doesNotUnderstand:aMessage

    "Modified: 24.4.1996 / 19:53:27 / cg"

!

loadAndResendMessage

    "common helper to autoload a class and define a subclass of it by sending

     the sender-message again.

     This is invoked by all #subClass... definition messages."

    |sel args newClass|

    sel := thisContext sender selector.

    args := thisContext sender args.

    "take care: subclassing Autoload must still be possible"

    (self == Autoload) ifTrue:[

	^ self perform:sel inClass:Autoload class superclass withArguments:args

    ].