object.enable() anti-pattern

[Fábio Santos]

On 13 May 2013 08:40, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Mon, May 13, 2013 at 4:32 PM, Fábio Santos <fabiosantosart at gmail.com>
wrote:
> >
> > On 13 May 2013 00:22, "Greg Ewing" <greg.ewing at canterbury.ac.nz> wrote:
> >> The same argument can be applied to:
> >>
> >>    foo = Foo()
> >>    foo.do_something()
> >>    foo.enable() # should have done this first
> >>
> >> You're passing an invalid input to Foo.do_something,
> >> namely a Foo that hasn't been enabled yet.
> >
> > I don't think you can really count that as invalid input in OOP terms.
After
> > all in most languages `self` / `this` / whatever is not an argument to
every
> > method.
>
> Yes, it is; it's just often implicit. C++ lets you poke around with
> the internals, and it's pretty clear that 'this' is an argument. (See
> for instance what happens with the gcc 'format' attribute - I can't
> find a convenient docs page, but it's been mentioned on SO [1] and can
> be easily verified.) EMCAScript lets you call any function with any
> 'this' by using the .call() or .apply() methods - which, in my
> extremely not-humble opinionated opinion, is bad design (closures work
> implicitly, but the 'this' pointer doesn't??). Python turns an
> attribute lookup on an instance into an attribute lookup on the class
> plus a currying. One way or another, the bit-before-the-dot is an
> argument to the function.
>
> [1]
http://stackoverflow.com/questions/11621043/how-should-i-properly-use-attribute-format-printf-x-y-inside-a-class
>
> ChrisA
> --
> http://mail.python.org/mailman/listinfo/python-list

I know ECMAScript does that. It would be nice to be able to pass an
instance method as a callback argument without using `.bind(theInstance)`.

At any rate, exposed or not, that is all still internals. Exposing the
ability to set the ` this ` as an argument is, I think, a functional
feature (map(str.strip, file) is a good example)

That said, I didn't know c++ did that, but it makes sense with what I read
somewhere about c++ starting out as a transcompiler-to-c-based language.
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