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<div class="" style="word-wrap:break-word">Sorry, I didn’t attach the example world. Here it is.
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<div class="">James<br class="">
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James Vanderhyde<br class="">
Assistant Professor, Computer Science<br class="">
Program Director, Master of Applied Computer Science<br class="">
Saint Xavier University<br class="">
3700 W. 103rd St.<br class="">
Chicago, IL 60655<br class="">
773-298-3454</div>
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<div class="">On Apr 6, 2017, at 4:17 PM, Vanderhyde, James <<a href="mailto:vanderhyde@sxu.edu" class="">vanderhyde@sxu.edu</a>> wrote:</div>
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<div class="" style="word-wrap:break-word">My students today hit an unexpected problem working with a list. They were doing Exercise 4 in Chapter 9 of Dann, Cooper, Pausch 3rd edition (p. 281): Casting a Beach Scene. The exercise instructs the students to create
an interactive animation where the user clicks on actors to add them to a list.
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<div class="">The problem came in when the students tested their programs. The program was written correctly, but sometimes not all the actors that were clicked got added to the list. It turned out the students were clicking too fast. I discovered that the
“insert object at end of list” instruction (and the “set item i to object in array” instruction) has a 1-second duration by default. This is inconsistent with the “variable set value” instruction and “increment variable by 1” instruction, which are both 0
seconds by default.</div>
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<div class="">I am attaching an Alice world that shows the problem. Clicking on the bunny adds it to a list and an array. If you look at the World properties when you play, then click rapidly on the bunny, you see the list update immediately but the array wait
1 second between updates. This is because I specified “duration = 0” in the list insert, but I left the array set item at the default duration.</div>
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<div class="">Thanks for looking at this. It would be nice to have consistent behavior.</div>
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<div class="">James<br class="">
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<div class="" style="letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; white-space:normal; word-spacing:0px; word-wrap:break-word">
—<br class="">
James Vanderhyde<br class="">
Assistant Professor, Computer Science<br class="">
Program Director, Master of Applied Computer Science<br class="">
Saint Xavier University<br class="">
3700 W. 103rd St.<br class="">
Chicago, IL 60655<br class="">
773-298-3454</div>
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