[Seaside-dev] Seaside's use of class-side #initialize

[Tobias Pape]

Hi John

On 27.01.2015, at 22:06, John O'Keefe <wembley at instantiations.com> wrote:

> Tobias -
> 
> Thanks for the information.
> 
> A VA Smalltalk Application is equivalent to a Monticello Package. A VA Smalltalk ConfigurationMap is approximately equivalent to a Metacello Configuration. So loading a VA Smalltalk Application is the same as loading a Monticello Package.
> 

Ok, thanks for clarification.
To my knowledge, yes, a class initializer is only triggered upon change of it
or its first installment. What you can do, however, is to use a 
	preamble or postscript
for Monticello (based on PackageInfo scripts) which is executed when a package is loaded.
I would abstain from using this for application specific state.

Also the guard code you saw is the way I would probably guard that application
initialization is done only once…

Best
	-Tobias


> John
> 
> John O'Keefe [|], CTO/Principal Smalltalk Architect, Instantiations Inc.
> Skype: john_okeefe2     Mobile:  +1 919 417-3181 (Business hours USA Eastern Time zone (GMT -5))
> john_okeefe at instantiations.com
> http://www.instantiations.com
> VA Smalltalk...Onward and Upward!
> 
> On Tue, Jan 27, 2015 at 12:27 PM, Tobias Pape <Das.Linux at gmx.de> wrote:
> Hi,
> 
> On 27.01.2015, at 18:13, John O'Keefe <wembley at instantiations.com> wrote:
> 
> > I'm trying to work through an anomaly in our VA Smalltalk Seaside implementation and it seems to boil down to a difference between Pharo and VA Smalltalk in when the class-side #initialize methods are run.
> >  * On Pharo, they are only run if the source for the #initialize method that is being loaded does not match the source of the #initialize method that was previously loaded (which is, of course, nil if the method does not already exist in the image)
> 
> This seems correct to me.
> 
> >  * On VA Smalltalk, they are always run when an Application is loaded
> 
> What is the semantics of "an Application is loaded"?
> 
> Best
>         -Tobias
> 
> >
> > Pharo's approach seems designed for #initialize methods with simple setter methods (like classVarA := 7). However, since the 'source code matching' doesn't recursively match the source code of methods being called from #initialize, nor is there any guarantee that called methods will always return the same thing even if their source hasn't changed, this seems like a flawed optimization to me (at least when complex #initialize methods are involved). But since it is what Pharo provides, I guess it is what you use.
> >
> > I also see this sort of code in several methods called from #initialize:
> >
> >  configureApplicationDefaults
> >     (configuredApplicationDefaults ifNil: [ false ]) ifFalse: [
> >        WAAdmin applicationDefaults
> >           at: #responseGenerator put: WAHtmlResponseGenerator.
> >        configuredApplicationDefaults := true ]
> >
> > This seems to be a guard against the VA Smalltalk style of class initialization.
> >
> > Can someone with a deeper understanding of the workings of Pharo than I have confirm that this is what is happening?
> >
> > Thanks, John
> >
> > john_okeefe at instantiations.com
> > http://www.instantiations.com
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