[TriPython] Let's talk about classes: invoking class methods with the class name

[Jeff Heard]

I would call it "message passing style" personally, but I'm not sure it has
a name.  similar though to the way Smalltalk or Common Lisp's methods
work.  I don't think it's "good python style" but you *could* technically
pass an object that is not of type LineSeg, not even related, and as along
as it "walks like a duck and quacks like a duck it would ... um, swim like
a duck.



On Thu, Nov 3, 2016 at 9:35 PM, Laura Tateosian <lgtateos at ncsu.edu> wrote:

>    Hello all,
>    I would like to hear your take on this. Say you have defined a class and
>    instantiated an instance as below.
>
>    class LineSeg:
>        def __init__(self, x1, y1, x2, y2):
>            self.x1 = x1
>            self.y1 = y1
>            self.x2 = x2
>            self.y2 = y2
>        def printSegment(self):
>            print 'Endpoint 1:( {0}, {1} )'.format(self.x1,self.y1)
>            print 'Endpoint 2:( {0}, {1} )'.format(self.x2,self.y2)
>    theSeg = LineSeg(1,2,3,4)
>    Then suppose you then invoke the printSegment method like below...
>    LineSeg.printSegment(theSeg)
>    This line is not what I would expect.   What is this approach called?
> Why
>    would you want to do this?  It works.  I can kind of see why it works,
> but
>    what are the pros/cons as compared to the standard approach like below?
>    theSeg.printSegment()
>
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>
-------------- next part --------------
   I would call it "message passing style" personally, but I'm not sure it
   has a name.  similar though to the way Smalltalk or Common Lisp's methods
   work.  I don't think it's "good python style" but you *could* technically
   pass an object that is not of type LineSeg, not even related, and as along
   as it "walks like a duck and quacks like a duck it would ... um, swim like
   a duck.
   On Thu, Nov 3, 2016 at 9:35 PM, Laura Tateosian <[1]lgtateos at ncsu.edu>
   wrote:

        Hello all,
        I would like to hear your take on this. Say you have defined a class
     and
        instantiated an instance as below.
          
        class LineSeg:
            def __init__(self, x1, y1, x2, y2):
                self.x1 = x1
                self.y1 = y1
                self.x2 = x2
                self.y2 = y2
            def printSegment(self):
                print 'Endpoint 1:( {0}, {1} )'.format(self.x1,self.y1)
                print 'Endpoint 2:( {0}, {1} )'.format(self.x2,self.y2)
        theSeg = LineSeg(1,2,3,4)
        Then suppose you then invoke the printSegment method like below...
        LineSeg.printSegment(theSeg)
        This line is not what I would expect.   What is this approach
     called?  Why
        would you want to do this?  It works.  I can kind of see why it
     works, but
        what are the pros/cons as compared to the standard approach like
     below?
        theSeg.printSegment()

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     [2]TriZPUG at python.org
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     [4]http://tripython.org is the Triangle Python Users Group

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