THANKS Hernan! With the example i've got to understand the correct usage of the pattern now. Which of course i will follow from now on, given the benefits from having complete objects! ( no messy ifNil checks for starters!, etc...)
On Oct 14, 2010, at 10:35 PM, Hernan Wilkinson wrote: > Hi Fernando, > I think that you are saying that having too many parameter could be a > problem for understanding the message, is that right? > I mean, having too many inst var as you say, it is a smell of bad design, > and having too many parameters also, so I guess we agree on that. > About reading the code, from the sender point of view, if you don't have an > instance creation message that creates a "complete" object, then you would do > something like this: > > performedExperiment := PerformedExperiment new > experimient: anExperiment; > start: aStartTime ; > stop: aStopTime ; > participant: aParticipant; > tasks: aCollectionOfTasks; > yourself. > > With an inst. creation message that returns a complete object, you would use > it like this: > > performedExperiment := PerformedExperiment > experimient: anExperiment > start: aStartTime > stop: aStopTime > participant: aParticipant > tasks: aCollectionOfTasks. > > So, it is basically the same but with less messages and less error prone (in > the former you can forget to send a message, ie. stop: and nobody will > complain immediately, but in the last one you wont make that mistake, or if > you doit you will get a dnu immediately). > > About the implementation of the inst. creation message, it is true that it > could bother a little the reading, but when there are so many parameters I > format the code this way: > > PerformedExperiment class>>experimient: anExperiment > start: aStartTime > stop: aStopTime > participant: aParticipant > tasks: aCollectionOfTasks > > ^self new initializeExperimient: anExperiment > start: aStartTime > stop: aStopTime > participant: aParticipant > tasks: aCollectionOfTasks > > that makes it more readable. > Also look that there is an initializeXxx message to distinguish it from the > inst. creation message. This helps when analyzing code automatically (ie. > initialize messages should only be sent from the class side) or generating > code automatically on the debugger with the create button (as the enhancement > 3099 that I sent the other day, the debugger could be smart enough to realize > it is an initialization message so it could provide a better template than > just a "self shouldBeImplemented"). > I the meantime, I would suggest another name for the message you are using as > example, something easier to read like: > > performedExperiment := PerformedExperiment > for: anExperiment > startedAt: aStartTime > stopedAt: aStopTime > madeBy: aParticipant "Not sure what participant is, so maybe madeBy is > not a good name" > with: aCollectionOfTasks. > > I think it reads better. With the former you have duplicated "names" like > "experimient: anExperiment", "start: anStartTime", etc., with the last one > you don't have that problem. > > Hope it helps, let me know what you think! > > Hernan. > > > On Thu, Oct 14, 2010 at 4:48 PM, Fernando olivero <[email protected]> > wrote: > Hi Hernan, just wanted to get your opinion on the following method, that > attempts to adhere to your "complete objects" pattern. ( ESUG 2010 TALK). > > PerformedExperiment>>experiment: anExperiment start: aTime stop: aStopTime > participant: aParticipant tasks: aCollectionOfTasks > | experiment | > experiment := self new. > experiment experiment: anExperiment start: aTime stop: aStopTime > participant: aParticipant tasks: aCollectionOfTasks. > ^ experiment > > > In your experience, how does the pattern cope with large keyword selectors. > > Maybe this case is not that evident, although we should try to avoid having > more than 4 instance variables anyway, i would like to get your opinion on > this problem (?). > > Thanks, > Fernando > _______________________________________________ > Pharo-project mailing list > [email protected] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > > > > -- > Hernán Wilkinson > Agile Software Development, Teaching & Coaching > Mobile: +54 - 911 - 4470 - 7207 > email: [email protected] > site: http://www.10Pines.com > > <ATT00001..txt>
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