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Sum2000 Midterm Review: History of Objects

(a) Ivan Sutherland produced Sketchpad at MIT in 1963. It allowed for the creation of "instance" drawings and "master" drawings. Any change to a master changed an instance of a drawing. Furthermore, these images could be moved around on a canvas as unique graphical entities without becoming merged into the background. For more info, see pg. 17 in the class book.

(b) Simula, the first OO language, was developed in Norway for the purpose of doing simulations, back in the 60's. Bjarne Stroustrup decided he wanted to create a more efficient version of Simula, so in 1984 he created C++.



So what does Sketchpad's drawings have to do with objects? (Don't quote from the book – it's not an open book midterm.) Mark Guzdial

You know, this question looks awfully familiar from somewhere. For part a), iirc, the concept of an object is essentially derived from the template Sketchpad lays out for drawings. The master drawing is very similiar to a class, where any copys of the master reflect all the features of the master itself, and any changes to the master are immediately updated into the copys, hence the idea of instances of a class. Similiarly, making changes to the copy drawings does not affect the master drawing, in the same way that changing variables in an instance does not predetermine the values of variables in any new instances created from the class (that may be a bit of a roundabout way to state that particular idea, but I think it makes sense). As to part b).....well, I don't really like the second letter of the alphabet anyway, so I'll leave that bit to others. Shaggz Mickley
Note: this answer is not complete, it only somewhat clarifies what Mark is asking for above. -shaggz
Or perhaps it doesn't.



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