[Tutor] Simple Question On A Method (in subclass)

[Chris Kavanagh]

On 10/24/2011 12:06 AM, Marc Tompkins wrote:
> On Sun, Oct 23, 2011 at 8:08 PM, Chris Kavanagh <ckava1 at msn.com
> <mailto:ckava1 at msn.com>> wrote:
>
>     So we have {member.tell} as the last line of code. So trying to
>     understand this piece of code, {member} the variable is considered
>     an object? Therefore we can combine it with a function {tell()}
>     using dot notation?? Is this correct??? I haven't seen anything but
>     an object combined with a function using dot notation. When I say
>     "object", I mean an "object" created from a class. So I'm trying to
>     figure out how we can combine the variable {member} with the
>     function {tell}. Hope this question makes sense to you, LOL. Thanks
>     again.
>
>
> First of all: other languages distinguish between variables and objects,
> and between functions and objects, but in Python both variables and
> functions are objects.  EVERYTHING is an object.  This is an important
> thing to remember - even if you never create classes of your own (which
> would be a terrible waste, BTW) a lot of the language won't make sense
> unless you remember that everything's an object.
>
> Second, the line "members = [t, s]" creates a list "members" (which is
> also an object, by the way!) containing two objects - "t" is a Teacher,
> "s" is a Student - which are both subclassed from SchoolMember.
> The line "for member in members" means: step through the list "members"
> and work with each object we find in it; let's call that object "member"
> while we're working with it.  As soon as we finish with the first object
> and move on to the next, call the next one "member" - and so on.  The
> beauty of this approach is that it simply doesn't matter what the
> contents of the list are - one could be a Student, the next a
> WoollyMammoth - and as long as your code only references methods and
> attributes that work for all the items in the list, Python won't care.
>
> Third, dot notation:  objects have "methods" (which in non-OOP contexts
> would be called "functions") and "attributes" (variables, more or
> less.)  From outside of the class definition, you refer to the object's
> attributes like so:
>      variable = object.attribute # if you want to read the attribute's
> current value
> or
>      object.attribute = variable # if you want to set the attribute to a
> new value
>
> and to its methods like so:
>      variable = object.method(parameter1, parameter2, etc)
>
> Like all functions, methods can take a fixed number of parameters, an
> optional bunch of named parameters, or no parameters at all; they may
> return a value or they may not; you may want to use that value, or
> ignore it.
>
> Things to remember:
> -you can get a value from a method, but you can't assign to it:
>      variable = object.method()
> but NOT
>      object.method() = variable
>
> -the only visible difference between reading an attribute and calling a
> method with no parameters is the parentheses at the end.  Don't forget
> them, and don't be misled by the similarity.
>
> Hope that helps...
>

Thanks so much for the explanation Marc!

My problem was, I wasn't seeing {member} as referring to the class 
objects {t} and {s}. Since it was, we now can use member just like any 
class object, and combine it with class functions (and class variables), 
such as {member.tell}. I had never in my short programming experience, 
seen an example like this. So I was confused, obviously, LOL.

Makes perfect sense now. . .Thanks again Marc (and Alan, Dave)
BTW, do you guys luv Python the way I do!?? I just luv the way 
everything works together so explicitly. I LUV learning this stuff!!