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Sp2001 Midterm Review: History of Objects

Show you know the history of objects here:

A. (7) How did an early drawing tool influence object-oriented thought?

–Sketchpad by Ivan Sutherland at MIT, was the first object-oriented graphics editor. It allowed its users to create objects that "INHERIT" from other objects. If the master object was edited, then all the subobjects also inherited this property. So sketchpad influenced object-oriented thought by introducing this concept of inheritance.

B. (8) What do simulations have to do with the creation of C++?

–Simulations are created inside simula which was a piece of software that worked on an object oriented level. Each simulation had its own class, and objects could not mess with each others insides. Bjarne Stroustrup wanted to create a more efficient version of simula and so because at the time he worked at Bell Labs were C was being used–he built this object oriented functionality into C and c++ was born.


Second one is slightly askew, e.g., Stroustrup wasn't trying to create efficient Simula. Top answer is similarly slightly askew, e.g., the object didn't have subobjects. Mark Guzdial

Ok, here is why I put that for the first answer...
quote from page 5 of our book

"...was the first object-oriented graphics editor, in the sense that we know it today. ... You created objects that could be manipulated as distinct from other objects. Even more significantly, Sketchpad allowed one to define a "master drawing" from which one could define a set of "instance drawings" Each of these instance drawings would be just like the master drawing, and if you changed the master, all the instances would change in the same way. The ideas in sketchpasd were the start of inheritance, where structure and behaviour are passed on from some objects to others..."

To me this says objects had subobjects in such a way that you can manipulate subobjects from their parent objects hence the idea of inheritence. I don't understand what kind of an answer is wanted here. Can you point me in the right direction?

As for the second part here is another quote from the book page 13 this time:

"Back in 1979 a separate thread of the object-oriented programming languages story was launched by Bjarne Stroustrup, who wanted to create a highly-efficient version of Simula."

This paired with the fact that he was using C at the time because he was working for bellabs was my basis for the answer... I guess I'm a little off, I would appreciate it if these discrepancies could be clarified. Thanks.
Arkady Shraybman

"instance objects" is not the same as "subobjects." Instances aren't subclasses. You caught me on the Stroustrup one, though. Mark Guzdial


If there is somebody who is so knowledgeable here, could that person please post the perfect answer? I think it's more productive to study the correct answers rather than to study why wrong answers are wrong.

chok
yeah, maybe you should read the Squeak book Mark. It has a lot of good info in it :)



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