On 22/03/2016 07:24, Marko Rauhamaa wrote:
Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info>:
I applaud you writing different versions of code to try different
tactics, but you should start from "write the most natural Python code
you can" *before* you trying guessing what's fast and what's slow.
I'm hard-pressed to imagine a situation where I would write *unnatural*
Python code for performance gains. Choosing a good algorithm applies to
Python programming as well, but convoluted optimization tricks, hardly.
On Tuesday 22 March 2016 11:49, BartC wrote:
No, it passes only a reference to the entire string.
In Python terms, that *is* "the entire string".
The point is, under the hood of the interpreter, *everything* passes
along references. We rarely draw attention to this fact. Given:
function(1.5, [])
we say "pass the float 1.5 and an empty list to function", not "pass a
reference to the float 1.5 and a reference to an empty list to a
reference to the function", because that would get rather annoying
quickly.
Hm. Annoying to repeat, sure, but I don't know how you could extricate
pointers from Python's abstract data model (or Java's, or Lisp's).
Prolog or a purely functional programming language could get away
without pointers but not Python.
I don't recall seeing any reference to "pointers" above. In fact, I
don't ever recall seeing references to pointers in the Python docs.
There's certainly nothing here
https://docs.python.org/3/reference/datamodel.html
But that's the critical point: it is *behind the scenes*, an
implementation detail.
I don't think there is any way to implement, think about or define
Python without pointers.
I never think about pointers, I think about objects. Heck, I wouldn't
have a clue as to how you go about implementing Jython or IronPython in
terms of pointers. I don't even know what anybody could mean by that.
In Python code, you don't pass "a reference to" 1.5, you pass 1.5.
Likewise for all other objects. The abstraction is that you pass
objects around, not references to objects.
The devil is in the mutables...
Whereby these mysterious "pointers" suddenly leap into action I take it?
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
--
https://mail.python.org/mailman/listinfo/python-list
