From: Fabian Streitel <karottenreibe@...>
Date: 2009-09-01T17:02:04+09:00
Subject: Re: Private methods’ viability (was: What is the ruby conventions to name private method?)

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same as you said :-)

I'm excited to hear Ryan Davis's approach since he claims to never use
private
methods at all.

2009/9/1 Tony Arcieri <tony@medioh.com>

> I also use private methods to separate out internal implementation detail=
s
> 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 lov=
e to
> > > hear your (and others=92!) reasons for the above and/or against the
> below.
> > :)
> > >
> > > I use private methods when I factor them out of my public methods (on=
ce
> > > 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 outsid=
e
> > > world (and should be promoted to public API with individual,
> descriptive
> > > 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 fr=
om
> > > the outside world=B9, hence I=92d rather not expose such instance var=
iables
> > > more than necessary.
> > >
> > > =B9 It=92s one of the few places where Ruby diverges from the princip=
le
> > > of least surprise; I can see certain lovely symmetry and simplicity
> > > in attr_reader working the same for all variables, but I found the na=
me
> > > a bit misleading when I started to learn Ruby =96 my thoughts were th=
at
> > > 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, a=
nd
> > > 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 logi=
c.
> > Sure something _could_ be used elsewhere, or for reasons that I haven't
> > considered, but it pollutes the public namespace, and obfuscates the AP=
I.
> > The outside world doesn't need (or probably want) to be subjected to th=
e
> > 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 a=
t
> > 181
> > methods, more than half of which are irrelevant, every time I was tryin=
g
> to
> > find something.
> >
> > This is the main reason I use private methods. I also use Rails, in whi=
ch
> > 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 ha=
s
> > 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.
> >
>
>
>
> --
> Tony Arcieri
> Medioh/Nagravision
>

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