On 15/01/24 10:23, Chris Angelico via Python-list wrote:
On Mon, 15 Jan 2024 at 08:15, Left Right <olegsivo...@gmail.com> wrote:
Python grammar rules prevent function definition from
appearing in left-hand side of the head of the for loop. However, a
variable declaration, which is also a statement, is allowed there.
What is a "variable declaration" in Python? Please elaborate.
We may be in danger of disappearing down an unintended 'rabbit hole'
with this side-discussion (he says, with graceful under-statement).
The basic challenge came from my earlier (and blasé) repetition of the
Python refrain "everything in Python is an object". Which led to:
<<<
For example, you may say "functions in Python are
objects", but you cannot put a function definition in the head of the
for loop clause.
>>>
Which is logical - to some degree, and in-isolation.
for def a_function( etc )... in iterable/iterator:
does not make sense. The 'head' (a more generic name, where Python says
"target_list", that refines down to 'something which can identify the
generated-value'.
So, no, there's an "everything" which (might be) an object but which
cannot be used in that scenario.
Two "howevers":
However, instead of looking at the narrow clause, (third comment about
wording not being taken as an whole!!!)* the full quotation was:
<<<
In Python, everything is an object. As long as the LHS is a legal-object
which makes sense for the situation, it can be used.
>>>
Context!
However, from the docs: "A function definition defines a user-defined
function object (see section The standard type hierarchy)". Accordingly,
is a function-definition an object? No! It defines an object.
That said, does anyone think that something like:
for a_function( etc ) in iterable/iterator:
is acceptable?
- see both Python definition and (full-)quotation.
I've not come-across a language which does allow such - YMMV/mea culpa;
and am struggling to see how it could possibly be useful.
In-turn, how this discussion could become profitable...
* Looking at the correspondent's email-address (cf 'handle') - and as an
unfair stereotype, raises the question of issues related to (English)
language-skills - which, arrogantly implies/assumes that native
English-speakers are all highly-capable. (?) A negative-interpretation
is to note his apparent intelligence, but wonder if failing to represent
others' comments fairly is deliberate, or carelessness. Is there an
irony in behaving/failing in such, whilst attempting to hold Python's
structure to some golden-ideal?
Web.Refs:
https://docs.python.org/3/reference/compound_stmts.html#the-for-statement
https://docs.python.org/3/reference/simple_stmts.html#grammar-token-python-grammar-target_list
https://docs.python.org/3/reference/compound_stmts.html#function-definitions
--
Regards,
=dn
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