[Tutor] Regarding Python api script

[Steven D'Aprano]

On Thu, Dec 06, 2018 at 09:13:01PM -0500, Avi Gross wrote:

> But so much code I see in python does not only reuse the same variable names
> but in a confusing way.
> 
> file =  "some name"
> file = open(file, "r")
> file = some_wrapper(file)

I agree this is confusing: you have the same name, "file", used to mean 
a file name, an open file object, and whatever some_wrapper returns. 
This is not the clearest code I've ever seen.


> mylist = [ ... ]
> mylist = sorted(mylist)

There's nothing wrong with that, except that it ought to be written:

mylist = [ ... ]
mylist.sort()

to sort in place instead of making a sorted copy.



> for index in range(...):
>   stuff
> 
> for index in open(...)
>   more stuff


Using "index" to iterate over the lines in a file is just a crappy 
choice of name.



[...]
> I have often seen something like this done with methods, such as to emulate
> decorator functionality where a method is created in an object with a name
> and the very next method created has the same name with the same function
> name as an argument to replace it.

I don't understand this. Can you show an example? Even if made up?


> So is there a guide on when reuse is good and when it just obfuscates? What
> is good practice?

If you pick *meaningful* names, it will be pretty obvious when to reuse 
the same name: is the name still meaningful? Then you MAY reuse. If the 
name is not meaningful, then you MUST NOT reuse it, unless you are 
deliberately writing obfuscated code.

If you have a name "column" which you use for a columns, then you 
shouldn't reuse it for rows, or lines of text read from a file, or the 
length of a list, or the date. But you can reuse it for another column, 
provided there's no confusion over which column is which.

The same applies to any other language.



-- 
Steve