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<p>Hi all,</p>
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<p>recent discussions have shown just another time that in spite of its overall modular and object-oriented design, the Morphic System still incorporates a number of global state variables that impede modular processes in some situations. For instance, running
or even debugging any form of UI simulation code in a background process was likely to cause problems because, via the global state variables, two planned-to-be-independent projects undesirably shared their events, hands, and worlds. Concrete systems suffering
from this global state include various UI tests executed using AutoTDD [1], or the screenshot generation framework for Squeak by Example [2] which I had the joy to co-develop.</p>
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<p>The attached changeset tackles these issues for all packages in the Trunk by wrapping the following three globals into process-local accessors: ActiveEvent, ActiveHand, and ActiveWorld.</p>
<p>As the changeset contains patches of over 300 selectors in more than 100 classes every single line of which you probably will not feel like reading in detail, here is a summary of all changes I applied:</p>
<p></p>
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<li>Added #activeEvent[:], #activeHand[:], and #activeWorld[:] process-local accessors on Object as Morphic-Kernel extensions. The actual values are stored directly on the active process in the manner of a <span>ProcessSpecificVariable. For backward compatibility,
the global variables are still kept up to date here.</span></li><li><span>Added #activateHand:during: and #activateWorld:during: as dynamic scope setters on Object as Morphic-Kernel extensions.</span></li><li><span>Replaced all references to ActiveEvent, ActiveHand, and ActiveWorld by "self activeEvent", "self activeHand", and "self activeWorld" accordingly. I also spent some time reflecting in which cases you actually would like to receive a possible nil value
and ended up with changing the most senders that are not involved into the critical event processing logic into their "#current*" equivalents (#currentEvent, #currentHand, and #currentWorld) which already guarantee to return non-nil values. In the case of
#currentWorld, I also replaced many senders with "Project current world" that were not invoked in an event-related context.</span></li><li><span>While skimming over all the implementations, I also applied a number of really minor refactorings: improve multilingual support by adding some "#translated"s to user strings, remove nil checks that could never be reached, and reformat some of the
very hardest to read methods I came across.</span></li></ul>
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<p>Please review! I'm looking forward to eliminating these unnecessary artifacts of global state and making Squeak an even more purely object-oriented and modular system by merging these changes into the Trunk.</p>
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<p>Best,</p>
<p>Christoph</p>
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<p>[1] <a href="https://github.com/hpi-swa-teaching/AutoTDD" class="OWAAutoLink" id="LPlnk685907" previewremoved="true">https://github.com/hpi-swa-teaching/AutoTDD</a></p>
<p>[2] <a href="https://github.com/codeZeilen/SqueakByExample-english/" class="OWAAutoLink" id="LPlnk356955" previewremoved="true">https://github.com/codeZeilen/SqueakByExample-english/</a></p>
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