[squeak-dev] The Trunk: Monticello-dtl.674.mcz

David T. Lewis lewis at mail.msen.com
Thu Dec 28 06:17:18 UTC 2017

Hi Eliot,

On Wed, Dec 27, 2017 at 09:41:49PM -0800, Eliot Miranda wrote:
> Hi David,
> > On Dec 27, 2017, at 9:37 PM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> > 
> > Hi David,
> > 
> >    compiledCodeClassNames  is a mistake.  There are no restrictions on the number of subclasses of CompiledCode.  What tells us if a class is that if code is its format which is expressed in the type information in its class definition, /not/ its name.
> > 
> > _,,,^..^,,,_ (phone)
> If your intent is to ease moving Code between Spur and prior versions then
> a) provide some special case for importing prior code, but do not impose that restriction on the current versions. 
> b) Both the prior version and Spur express the compiled codeness of a class in the class's format, with the name being merely incidental.  One can back port the work to express that through the class definition.

The failure occurs when reading an MCZ into a V3 image, when MCStReader>>classDefinitionFrom: 
creates a new MCClassDefinition from the information provided in a PseudoClass instance. The
PseudoClass does not contain the necessary information about compiled codeness.

This code path does not seem to be followed in a Spur image, I'm not entirely sure why.

> Restricting the code loader by recognizing specific class names puts toad blicks in the way of future code.  It is worse than isKindOf:

I agree but don't have a better solution to offer. It would be possible to
use to the actual class to which the PseudoClass refers, but I fear this
would not work in the case of a MCClassDefinition for a class that does not
yet exist in the image.


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