On Jul 12, 8:05 am, Robert Lehmann <[EMAIL PROTECTED]> wrote: > On Fri, 11 Jul 2008 20:13:04 -0700, happy wrote: > > Can a variable be considered the simplest of the data structures. I am > > tutoring some kids about basics of programming using python. Not an > > expert in computer sciences, but am a python enthusiast. > > Why do you need this additional layer of indirection? Just explain the > real simple data structures à la "look, kids, a string is a chain of > characters which are bytes actually. <insert explanation about encodings > etc. here>". Although explaining encodings is an *important* thing (which > many programmers still get wrong), it might be second priority to kids > and you might just want to say "a string is text" and jump into higher- > order data structures. > > > I wanted to know if it is correct to say a variable is a data structure, > > it has a name and a value. > > Not at all. This sounds a lot like an explanation for variables in other > languages (such as C, where the value also has a type). In Python, we use > to speak of "names," not variables. They are more like name tags you can > put on objects -- or you don't. Depending on the age/interest of your > students, I'd insert an explanation about references, reference counting > and garbage collection here (they usually find that quite understandable > and it paves the way for The Real Stuff, even though you might argue that > the refcounting gc is a CPython detail and might become obsolete with > PyPy's rise <wink>). > > The important thing is really that Python's approach of references is > nearly orthogonal to the common approach of variables. In other > languages, variables are (as you described above) containers (a bucket, > really!) in your memory where you can put stuff into. Assignment is > usually a copy or pointer operation. > Python does not care at all about your memory. You have abstract objects > (incidentally saved in your memory, okay) with names being one mechanism > to reference them. Here, assignment is always a "put the left-hand side > name tag onto the right-hand side object". > > > Put a stack of variables in a special data > > structure called a dictionary where the each name associates to a value. > > If in a data structure, one uses numbers starting from 0 to describe the > > name, it becomes a list and so forth.... > > First off, you really put objects in your data structures. Names are a > one-way mapping -- the object does not know which name tags are assigned > to it. > > Your explanation of dictionaries and lists sounds a little bit upside- > down (not the mapping name->value or number->value makes it a dict or > list -- the data structure makes it a mapping with this and that > behaviour). > > HTH, > > -- > Robert "Stargaming" Lehmann
Thanks for the reply. I think its better to leave the "teach kiddies" tutoring opportunity for the python experts out there. Would "python experts" have an appetite for newbies and "kiddies"? Only time will tell... I must really focus on learning the language better. "Look kids, you will learn it when you grow up... Now get out of here..." -- http://mail.python.org/mailman/listinfo/python-list
