Thanks again for all your help Kent and Dave. I think you won't here from me for a week or more as I digest your advise and work on my project.
Thanks Vincent Davis 720-301-3003 On Sun, Nov 1, 2009 at 6:34 PM, Dave Angel <da...@ieee.org> wrote: > Kent Johnson wrote: > >> On Sun, Nov 1, 2009 at 10:47 AM, Vincent Davis <vinc...@vincentdavis.net> >> wrote: >> >> >>> Kent Johsnon writes >>> "This class has a lot of responsibilities: >>> - create applicants >>> - create institutions >>> - run a single match >>> - run multiple matches >>> - calculate statistics on the result of multiple matches >>> A principle of object-oriented design is that a class should have a >>> single responsibility. I would break your class up a bit using >>> multiple classes, perhaps." >>> I am trying to do what you recomend, as much as makes sense to me, but >>> that >>> is why I ask the question so I should consider your answer. >>> This is what I hear you saying, (I don't mean to represent them as >>> sub-classes but more how they would operate on each other) Should I >>> consider >>> making Institutions) a subclass of (Make Institutions)? I can't think of >>> anything that would make sense to inherit. >>> class Simulation: >>> class Create Institutions: >>> class Institutions: >>> class create Applicants: >>> class Applicants: >>> class Match: >>> class Multi Match: >>> I add I am thinking >>> class Simulation: >>> def__init__:(self, results, stats.....repeat..) >>> def create_applicants(): >>> class Applicants >>> def creat_institutions(): >>> class Institutions >>> def one_simulation(): # one or more >>> create_applicants() >>> create_institutions() >>> class Match() >>> class Results >>> def repeat_simulation() >>> repeat one_simulations >>> class Results >>> After writing this out I now think you are right, more classes. >>> >>> >> >> Now you are getting too complicated. You don't need to use inheritance >> or nested classes, and you can use simple methods (not classes) to >> create applicants and institutions. You already have Applicant, >> Institution and Match classes that run a single match. Now make a >> RepeatMatch class that uses the Match class to run multiple >> simulations. >> >> Kent >> >> >> > I mostly agree with Kent, but I apparently disagree about which classes are > actually needed. Think what things will have actual instances that will > last long enough to be worth formally defining. So you need Applicant, and > Institution, and Simulation. Notice they're all singular. I'm assuming one > simulation is a single set of test data, with its results. Then you create > as many instances of Simulation as you need for comparison purposes, and > perhaps keep a list of them. It's not clear that list needs any further > structure than the built-in list type provides. > > You don't need a class for creating an Applicant, that's just a line or two > in a loop in the Simulation class. Similarly for Institution. > > And if I understand it correctly, you don't need very many different > methods in Simulation either. You need the __init__ to save enough > information to "tag" this particular simulation (call it a label, it's > probably just a string). If __init__ is too complex, you may want to break > it into several phases. But they'll always be called in direct succession, > so there may not be any point. Then you need something that triggers an > analysis, and something that queries for particular results. That last will > then be called from plotting or charting routines. > > But you probably don't need anything special for a collection of Simulation > objects. A list will probably be fine. > > And from what you said earlier, you WILL need function objects, probably as > parameters to the Simulation constructor. So each instance of Simulation > will be given several function objects to specify the distribution functions > for the parameters to be used when creating Applicants and Institutions. > > DaveA > > >
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