On Thu, Apr 29, 2010 at 4:53 AM, Henrik Johansen
<henrik.s.johansen@veloxit.no> wrote:
On Apr 29, 2010, at 1:44 29PM, Alain Plantec wrote:
> Henrik Johansen a �crit :
>> On Apr 29, 2010, at 11:30 06AM, St�phane Ducasse wrote:
>>
>> It's not a question of one vs. the other, really.
>> The cs doesn't change the Settings implementation, it simply adds support for also discovering settings defined in the pragma style used by Squeak.
>> The downside is you'd have two ways to define settings.
>> The upside is the
> the upside is ... :)
> well, I will have a look at the cs.
> I would prefer that this changes do not introduce any
> overwriting so that it can be loaded separately as a compatibility package.
> so, i will investigate the changes needed for the settingbrowser.
> is that ok like that ?
> Cheers
> Alain
It needs a way to register new valid preference pragmas, and setting generators for such pragmas.
May I suggest... using pragmas? ;P
This ids the way it works (and has worked for nearly 10 years) in VisualWorks. �On the class side one can declare the pragmas a class supports using pragmas. �One uses pragmas to avoid having one method that defines all pragmas for a class, which would create a potential conflict between packages of the kind that pragmas help avoid. �When the compiler encounters a pragma it searches the class side looking for the pragmas that are "in scope" at the moment. �The argument to the pragma: pragma is a symbol stating which side of the class the pragma is valid (why they don't support #both or #(class instance) I don't know). �Here are some examples:
AboutVisualWorksPage class methods for private
pagePragma
^#(pageOrder:)
systemPragma
^#(systemInformation:)
BlockClosure class methods for private
exceptionPragmas
^#(#exception:)
StandardSystemController class methods for resources
�menuMethodPragmas
^Menu pragmas
With this approach a package can add its own method annotations to a hierarchy without conflicting with any other package. �Here's the VW code that fetches the pragmas understood by a class:
Metaclass methods for compiling
recognizedMethodPragmas
^self soleInstance recognizedMethodPragmas: #class
Class methods for compiling
recognizedMethodPragmas
^self recognizedMethodPragmas: #instance
requiredRecognizedPragmas
^#(#pragmas: #primitive: #primitive:errorCode:)
recognizedMethodPragmas: type
"The 'type' argument may be either #class or #instance"
| list beh |
list := IdentitySet withAll: self requiredRecognizedPragmas.
beh := self class.
[beh isMeta] whileTrue:
[beh selectorsAndMethodsDo: [:sel :meth | | pragmas |
pragmas := meth attributeMessages.
pragmas == nil ifFalse:
[pragmas do: [:msg |
(msg selector = #pragmas:
and: [msg arguments first = type])
ifTrue: [list addAll: (beh soleInstance perform: sel)]]]].
beh := beh superclass].
^list
Simple, but fabulously meta. �Thank Steve Dahl for this idea.
Cheers,
Henry