On Thu, Jan 21, 2016 at 5:49 AM, Steven D'Aprano <st...@pearwood.info> wrote:
> On Wed, Jan 20, 2016 at 09:42:29PM -0600, boB Stepp wrote:
>
>> So I really only have one question: Why not make Python's
>> *traditional* name, "self", mandatory? Why give the programmer this
>> kind of choice? [OK, that was two questions.]
>
> Why bother making it mandatory? That just makes more work for the
> compiler -- it has to decide that a function is inside a class, and
> therefore apply a restriction to the first argument. Most of the time,
> giving the programmer more freedom is less work.
>
> And what happens if you do this?
>
> class X:
> pass
>
> def func(this):
> print("instance %r called method" % this)
>
> X.method = func
Am I understanding this correctly? It appears to me that you have
successfully added a method to class X from outside of class X! If
this is the case, then this clarifies some things I was wondering
about in my other thread.
> And what are we supposed to do with classmethods and staticmethods? They
> shouldn't take a "self" argument at all, but they start off life as a
> regular function, just like ordinary instance methods.
>
> And of course, there are Metaclasses. You might need a metaclass method
> that needs to deal with all three levels of the hierarchy: the
> metaclass, the class it creates, and the instance of that class.
>
> class Meta(type):
> def metamethod(meta, cls, self):
> ...
I scanned the article that Danny gave a link to. I am not ready to go
in depth into these concepts at this time, but I cannot help but
wonder about the possibilities these concepts open up? At work I find
myself writing Python to generate correct scripting language commands
for the proprietary software I use at work. What if I could write a
Python program which thoroughly captured the entire proprietary
scripting language into a much easier to use interface? Their
scripting language has an underlying OO structure that is not exposed
to my prying eyes. But *if* I could create a class structure that was
sufficiently similar to theirs that it seamlessly generated the
correct messages that their OOP style uses, then things might be much
easier for my projects. Hmm...
I guess I am trying to wrap my mind around this incredible power and
flexibility that Python provides. I thought I had asked a relatively
harmless question. But it generated some strong responses! It seemed
like "self" had a similar utility of use as "print" to me. After all,
we can't redefine "print", can we? But now I realize that I can do
exactly that if I so choose. That is both fascinating and scary!
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