From: Tony Arcieri <tony@...>
Date: 2009-09-01T07:45:33+09:00
Subject: Re: Private methods’ viability (was: What is the ruby conventions to name private method?)

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I also use private methods to separate out internal implementation details
that I expect to change (e.g. if we decide to switch to a different
algorithm).  I also decompose into small functions a lot, perhaps a side
effect of Erlang on the brain.

However, the instant I feel the urge to use __send__ to call a private
method I make that method public.

On Mon, Aug 31, 2009 at 4:29 PM, Josh Cheek <josh.cheek@gmail.com> wrote:

> On Mon, Aug 31, 2009 at 4:49 PM, Shot (Piotr Szotkowski) <shot@hot.pl
> >wrote:
>
> > Ryan Davis:
> >
> > > 4) Don't have private methods if you don't need them.
> > > 5) You don't need them. No, really.
> >
> > I=92ll bite. Note: I consider myself a beginner Rubyist and I=92d love =
to
> > hear your (and others=92!) reasons for the above and/or against the bel=
ow.
> :)
> >
> > I use private methods when I factor them out of my public methods (once
> > the public methods have decent spec coverage). This makes me think
> > harder on the (hopefully =96 minimal) public API of my objects and
> > prevents me from calling such methods =91in just that single place
> > where it would be useful=92; a method=92s either useful to the outside
> > world (and should be promoted to public API with individual, descriptiv=
e
> > spec coverage) or not, period. Using private methods helps me keep
> > checks on this.
> >
> > I also use protected attr_readers so that my objects can tell whether
> > they =3D=3D others of the same kind without exposing their instance
> > variables to the outside world; an attr_reader on an Array/Hash/Set
> > does not guarantee that the given Array/Hash/Set is not modifiable from
> > the outside world=B9, hence I=92d rather not expose such instance varia=
bles
> > more than necessary.
> >
> > =B9 It=92s one of the few places where Ruby diverges from the principle
> > of least surprise; I can see certain lovely symmetry and simplicity
> > in attr_reader working the same for all variables, but I found the name
> > a bit misleading when I started to learn Ruby =96 my thoughts were that
> > it should either not be called a reader or should return a dup of the
> > variable in question=85 (I did get used to this since then, though, and
> > realised that other languages=92 generic getters usually do the same.)
> >
> > =97 Shot
> > --
> > Born to be mild. [elpanda]
> >
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.4.9 (GNU/Linux)
> >
> > iEYEARECAAYFAkqcRXAACgkQi/mCfdEo8UpIWwCeNYQ+NZNW895936Gbnwj3btMA
> > ylYAnRbvAkMrzP0Ep6SW1y6kl07id7aV
> > =3D0fIP
> > -----END PGP SIGNATURE-----
> >
> >
> I do the same thing, I use private methods to encapsulate internal logic.
> Sure something _could_ be used elsewhere, or for reasons that I haven't
> considered, but it pollutes the public namespace, and obfuscates the API.
> The outside world doesn't need (or probably want) to be subjected to the
> internal logic of my code. Even I, using my own code later, prefer this
> approach, because it simplifies use.
>
> Take the Array class as an example, it has 96 private methods, and 85
> public
> methods. The public ones are the ones I almost certainly am looking for,
> how
> burdensome would it be if they made them all public and I had to look at
> 181
> methods, more than half of which are irrelevant, every time I was trying =
to
> find something.
>
> This is the main reason I use private methods. I also use Rails, in which
> private vs public is relevant because it affects behaviour. For example, =
a
> public method in a controller will try to render a template after it has
> been called.
>
> I have, however, experienced situations where things are irritating as a
> result of private methods, for example, in the API for define_method
> http://www.ruby-doc.org/core/classes/Module.html#M001654 it says "This
> block
> is evaluated using instance_eval, a point that is tricky to demonstrate
> because define_method<
> http://www.ruby-doc.org/core/classes/Module.html#M001654>is
> private <http://www.ruby-doc.org/core/classes/Module.html#M001641>. (This
> is
> why we resort to the send hack in this example.)" So it can make things
> difficult, as well.
>



--=20
Tony Arcieri
Medioh/Nagravision

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