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"Note that the object receiving the cascaded messages can itself be the result of a message send. In fact the receiver of all the cascaded messages is the receiver of the first message involved in a cascade. In the following example, the first cascaded message is setX:setY since it is followed by a cascade. The receiver of the cascaded message setX:setY: is the newly created point resulting from the evaluation of Point new, and not Point. The subsequent message isZero is sent to that same receiver.
Point new setX: 25 setY: 35; isZero−→false" Is not the first message in this cascade "new" and is it not "Point" that receives it? _______________________________________________ Sbe-discussion mailing list [hidden email] https://www.iam.unibe.ch/mailman/listinfo/sbe-discussion |
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Hi Blake, Read it again. You will see that the Point instance, not the class, receives the isZero message. Ergo, new is not the first msg of the cascade. Cheers, Oscar --- Prof. Dr. O. Nierstrasz -- [hidden email] Software Composition Group -- http://scg.unibe.ch/oscar University of Bern -- Tel/Fax +41 31 631.4618/3355 On 2013-09-19, at 1:50, blake <[hidden email]> wrote: > "Note that the object receiving the cascaded messages can itself be the result of a message send. In fact the receiver of all the cascaded messages is the receiver of the first message involved in a cascade. In the following example, the first cascaded message is setX:setY since it is followed by a cascade. The receiver of the cascaded message setX:setY: is the newly created point resulting from the evaluation of Point new, and not Point. The subsequent message isZero is sent to that same receiver. > > Point new setX: 25 setY: 35; isZero−→false" > > Is not the first message in this cascade "new" and is it not "Point" that receives it? > _______________________________________________ > Sbe-discussion mailing list > [hidden email] > https://www.iam.unibe.ch/mailman/listinfo/sbe-discussion _______________________________________________ Sbe-discussion mailing list [hidden email] https://www.iam.unibe.ch/mailman/listinfo/sbe-discussion |
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Right, I'm sorry--I wasn't being clear. I would probably format that code differently, at least for illustrative purposes. Or at least put in some clarifying text. If it were: Point new; setX: 25 setY: 35; isZero
You get an error because Point class doesn't have setX, etc. The difference is a mere semi-colon, easy to miss: Point new setX: 25 setY: 35; isZero So you might format it: Point new setX:25 setY: 25; isZero ===Blake=== On Wed, Sep 18, 2013 at 11:27 PM, Oscar Nierstrasz <[hidden email]> wrote:
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Right, good suggestion! (I almost wrote "good point".) Oscar
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