Re: Fluent programming in Ruby

Hi --

On Mon, 29 Oct 2007, [e-mail] wrote:

> [UTF-8] Wolfgang N=C3=A1dasi-Donner writes:=20
>> Please, please, please...-...don't change the syntax that
>> "Ruby" and "irb" don't accept the same things, or have different
>> syntactical elements for the same thing!=20
>> Wolfgang N=E1dasi-Donner
>
> First, as the person who started this thread, I'd like to point out that =
Matz=20
> has not actually asked any of us what we think about this new feature.=20
> The only objection I've heard to it that was mostly a matter of subjectiv=
e=20
> dislike for fluent APIs is this issue about irb.=20
> I think it is solvable. (Though I don't think it needs to be solved in 1.=
9.1.=20
> We can wait for 1.9.2...)=20
> Modify IRB so that when it sees an expression that begins with a ., it tr=
eats=20
> it as method invocation on the value returned by the last line.   A sessi=
on=20
> might look something like this:=20
>> "hello"
> =3D> "hello"
>> .upcase
> =3D> "HELLO"
>> .reverse
> =3D> "OLLEH"=20
> The only tricky part that I see (there may be others) occurs when there i=
s an=20
> assignment expression involved:=20
>> a =3D "hello"
> =3D> "hello"
>> .upcase
> =3D> "HELLO"   # What is the value of a?=20
> To solve this, I think that IRB would have to defer the evaluation of=20
> assignment expressions until it knows that the next line will not be a=20
> continuation.  If the next line does not begin with a dot then the assign=
ment=20
> will be done before that line is evaluated.  So if the next line uses the=
=20
> lvalue, that lvalue will have its proper value.  Seems like this would be=
=20
> transparent.=20
> If the lvalue is an attribute accessor with side effects visible outside =
of=20
> IRB (setting the attribute is supposed to cause a file to be created, for=
=20
> example) then there may be problems and using a semicolon would be necess=
ary,=20
> I suppose.

This seems like an awful lot of hoops to jump through, just so that
one rather specialized stylistic thing can have full sway.

I think that's what bothers me about this whole dot thing: it's a
concession on the part of the language to one use case. It strikes me
as a solution in search of a problem.


David

--=20
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