"Define before use" is a broad principle that I try to follow, even
when the code itself doesn't mandate this.
IMO it makes the code easier to navigate even when it's not strictly
necessary. As others have said, Python mandates that the functions be
defined before they're CALLED, but I find that it's worth being
stricter. As a general rule, any global name in my code (that includes
constants, module-level functions, etc, etc) will have its definition
as the textually-first instance of that name. Or, at worst, the first
instance will be a comment immediately above the definition.
('Anonymised' because this is not 'aimed' at any particular individual)
I was somewhat amused at being 'corrected' in the "defined" cf "called"
discussion. The 'corrections' are more precise. However such
distinctions are machine-related, ie how does the Python interpreter behave?
The central topic of this (ideally, thought-provoking) discussion, is on
the person (not the machine). Yes, the author. Although, if you
subscribe to the philosophy that program(me)s should be written with
human-readers in-mind, then the likes of "beauty is in the eye of the
beholder" and "readability counts", apply!
Various 'gurus', probably even before the Agile/Gang-of-Four/OOP, have
talked of code craftsmanship having a number of characteristics. One of
which is that *my* code should appear pretty-much as *you* expect the
solution. When we were asked to discuss this, over-the-teacups (on
Friday, hence the "FF" moniker) the young fellow's question was phrased
"what do you guys expect [from me]".
(yes, he was quoting/abstracting from 'Uncle Bob' and "Clean Code"
[Prentice-Hall, 2009]).
We have a number of 'what do you expect'-s in Python. For example, there
is no "law" saying that we must use "self" within classes. Other
languages use similar but alternate terminology, eg "this". I could
decide to use "dn_was_here" and the interpreter will be perfectly happy
- but because you don't expect it and would be made to (unnecessarily)
comprehend, I doubt it would promote our friendship/mutual-respect!
So, do you hold any 'expectation' relating to the organisation of class
methods?
--
Regards =dn
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