Python Newbie

Michael Torrie torriem at gmail.com
Mon Feb 25 02:42:05 CET 2013


On 02/24/2013 06:04 PM, Steven D'Aprano wrote:
> Variables do not have types in Python.
> 
> Reset your thinking. Python is a dynamic language with name bindings and 
> strongly-typed objects, not a static language with strongly-typed 
> variables. If you don't understand the difference, ask. But so long as 
> you make the wrong assumptions about the language, you will have a bad 
> time.

Yes, but according to my computer language theory class, strictly
speaking, python has no variables, only names and objects, which for the
most part aren't mutable.  A variable by definition is a box in memory
that you can write to.  The closest thing python has to that are
instances of mutable types like a list.

"a=5" certainly doesn't allocate a box in memory somewhere and stick 5
in it.  And then later "a += 1" or "a=6" doesn't mutate the value stored
in the box represented by a.  Instead it allocates a new object and
makes a refer to that new object.

I know all this is what you meant, but with the original poster's
frustrations with python, it's important that he just throw out the
notion of variations entirely because sooner or later that will get him
in trouble here, like if he tries to make an empty list be a default
value for a function parameter.



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