MVC is Dead?

Dan Ingalls Dan.Ingalls at disney.com
Wed Feb 2 18:16:43 UTC 2000


[A clarification -- when we at Squeak Central (SqC) refer to "MVC", we are usually referring to the "old ST-80 viewing structures" and their control regime (View/Ctlr, SSView/Ctlr, and ControlManager).  We consider the model/dependents architecture and change/update protocols to be of enduring value in Squeak as in MVC].

>At 09:34 PM 2/1/00 -0600, Les Tyrrell wrote:
>>If the support is there to power Morphic, I'd think that the
>>support will always be in place to resurrect MVC, should it
>>be dropped from the baseline.
>[snip]

"R. A. Harmon" <harmonra at webname.com> replied...
>I don't share your optimism on this point.  I think it would slowly become a
>dead path.  Less bugs would get fixed, less enhancements get added, less
>people use it, so less bugs would get fixed, less enhancements get added,
>less people use it, . . . .  It appears to me that additional "widget?" are
>added to morphic but not in a way that they can be used in MVC--I'm not
>familiar enough with morphic to tell for sure.

This is already the case -- MVC is currently maintained for backward compatibility (with documentation, etc) -- it is not the site of most enhancements and of Squeak's general forward motion (animation, 3D, music and sound support, etc).

>I think this is a route that will diminish Squeaks accessibility to folks
>new to Smalltalk as most books on Smalltalk and code freely available (other
>dialects) don't use morphic.  Trying to translate MVC to morphic adds a
>level of complexity to learning from the books and code.  This is enough to
>dissuade someone from getting over the OOP-think hump.

This is why we have kept MVC so far.  That familiarity and compatibility with other STs is a valuable component in the overall synergy.

Regarding the OOP-think hump, we at SqC consider NEITHER Morphic nor MVC to be adequate.  We still feel that an entirely new approach is needed here -- along the lines of Morphic viewers somehow integrated with a real inspector/browser/debugger, with maybe a few things borrowed from Fabrik and Morphic Wrappers.  Wish us luck (or beat us to it!).

>I think the newbies and tools are both useful in getting to the next plane.

Absolutely.

We do not plan to decommission (excise from the release) MVC until the time when nearly everyone who uses Squeak does so as an environment unto itself, not as a free alternative to other similar Smalltalks where MVC compatibility is important.  We feel that this could happen within the current year (but we had the same feeling a year ago ;-).  Whenever the time comes, we will produce a "Last Picture Show" image that is the cleanest and most complete MVC-based image possible, so that it can be used and maintained indefinitely by motivated MVC survivalists.

>>Isn't Morphic about due for the long-awaited refactoring?

Yes, indeed.  This is another nice thing about retaining MVC for a while.  It gives us a place to stand when making major changes to Morphic.

	- Dan







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