On 10.09.2016 15:00, Chris Angelico wrote:
Some things are absolute hard facts. There is no way in which 1 will
ever be greater than 2, ergo "1 is less than 2" is strictly true, and
not a matter of opinion. If you hear someone trying to claim
otherwise, would you let him have his opinion, or would you treat it
as incorrect?
I don't know exactly if it's clear that one would need to make a
distinction between real/physical-world facts and pure-logic facts.
"1 < 2" is by definition "true" (construction of natural numbers) not by
real-world evidence. IIRC, the quote is about real-world matters.
There is some merit in this. For instance, Python 2 had a lower-level
consistency in the division operator than Python 3 has. According to
Py2, integers and floats are fundamentally different beasts, and when
you divide an int by an int, you get an int, not a float. Py3 says
"well, you probably REALLY meant to divide a number by a number", so
it gives you a float back, unless you explicitly ask for floor
division.
Py2 is more consistent on a lower level of abstraction. Py3 is more
consistent on a higher level of abstraction (modulo the oddities at
extremely large numbers). Both have merit, but in a high level
language, the Py3 way is usually [1] better.
But the consistency of call-by-object-reference is at the same high
level as the consistency of call-by-value or call-by-name. I can
explain Python's assignment model to someone fairly easily, using
pencil and paper, without any reference to "low level" or "high level"
concepts. And Python is extremely internally consistent; *every*
assignment behaves the exact same way. How does "import x" compare
with "from x import y"? Easy: the former is "x = some_module_object",
and the latter is "y = some_module_object.y", and either way, it's
regular assignment. How does parameter passing work? You take the
value of the argument as evaluated in the caller, and assign it to the
parameter in the function. What about default arguments? They're
evaluated when the function's defined, and assigned to the parameter
when it's called. Function definition itself is the same thing - it's
assigning a function object to a name. Python handles every one of
them the same way.
I don't care one iota about how voltages inside a CPU operate. I don't
generally even care about machine code - let other people worry about
that, people more expert than I am. Discussions about how the core dev
and the novice see Python's consistencies are nothing to do with those
levels. To go back to your original point, that a newbie is better at
recognizing inconsistencies... maybe, in a sense, but they also get a
lot of false positives. Ultimately, "consistent" means that there's a
single pattern that explains everything; if you're unaware of that
pattern, you won't know that it's consistent.
ChrisA
[1] Even in Python, there are places where low-level consistency is
better, because Python is a glue language. But in general, it's better
for Python to be consistent with humans than with C APIs.
The last sentence is the part why I love Python. :)
I could not agree more with what you said above, so I hope this will put
the discussion in better perspective, especially when people here trying
to be overly absolute in their views (which was the quote about).
Cheers,
Sven
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