wait even in the above example i would have to run all the functions in __init__ that is plain stupid ... i was just brain storming....
On Mon, Jun 29, 2009 at 5:34 PM, Amit Sethi<amit.pureene...@gmail.com> wrote: > I think ideally i want a compile Error just like java .. but from the > discussion here ... i wrote this little example: > > class a(object): > def __init__(self): > self.query() > try: > if self.query_not_implemented==True: > raise NotImplementedError > except AttributeError: > pass > def query(self): > self.query_not_implemented=True > > At least by this when ever the derived class object is created without > implementing a particular function ,it raises a NotImplementedError > which i can later use. > > > @Dave Angel > > You have said > "you could arrange that when the plugin is first encountered, you > validate that it has all the required methods and data members. Not > by calling them, but by scanning the object for their existence." > > that would be ideal ... can you enlighten me on this how may one do that. > > > On Mon, Jun 29, 2009 at 5:01 PM, Dave Angel <da...@ieee.org> wrote: >> >> Amit Sethi wrote: >> >>> Well I want to implement plug-in like mechanism for an application . I want >>> to define some minimum functions that any body writing a plugin has to >>> implement. For that i thought an interface would be best because in a >>> scenario where the function is not implemented some kind of error would >>> occur. I would love to hear if you think their is a better way to achieve >>> this >> >> In Java, deriving a class from such an interface, but neglecting to >> implement those methods will cause a compile error (if I recall correctly, >> it's been several years). In Python, the error will happen at run time. >> But an existing runtime error will occur even without such an interface, so >> it wouldn't seem you gain much. In Python, the interface does two things: >> >> 1) it's a comment, a common place to look for certain behavior. >> 2) it's potentially a source for an IDE to provide tool-tips or code >> completion >> 3) it can generate a different error, which is perhaps more useful to the >> developer unsure of how the method is spelled or used. This way he/she >> knows whether to fix the caller or the implementation. >> >> #3 seems valid to me. >> >> >> >> However, for the particular use-case, you might want to stretch a bit >> further. Since you've got one "user" (your code), and many "providers" (the >> plug-in writers) perhaps you could arrange that when the plugin is first >> encountered, you validate that it has all the required methods and data >> members. Not by calling them, but by scanning the object for their >> existence. >> >> >> _______________________________________________ >> Tutor maillist - tu...@python.org >> http://mail.python.org/mailman/listinfo/tutor > > > > -- > A-M-I-T S|S > -- A-M-I-T S|S _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
