require!

[Ross Bamford]

It (finally) clicked now, 'require' is just a method...

Boy do I feel stupid. :|

On another note, though, I also found out that calling amethod(*args)
works with anything with 'each' (any Enumerable?), which made me smile. It
was the post about ranges that made me get that

Thanks!

 

[Trans]

Hi Ross, actually as Florian recently taught me, *obj works for any
object with #to_ary defined --if that is what you mean.

T.

 

[gwtmp01]

Hi Ross, actually as Florian recently taught me, *obj works for any
object with #to_ary defined --if that is what you mean.

Actually, I think the * operator looks for #to_a not #to_ary.

Gary Wright

 

[Ross Bamford]

Hi Ross, actually as Florian recently taught me, *obj works for any
object with #to_ary defined --if that is what you mean.

T.

I see... I was pretty happy when I realised it did it at all, and of
course it makes complete sense with hindsight. Thanks for pointing the way.

 

[Ross Bamford]

Actually, I think the * operator looks for #to_a not #to_ary.

Gary Wright

Some quick experiments just now suggest it looks first for to_ary, then
to_a. As I say, I was pretty pleased to find it did it at all so I didn't
carry on playing with it ...

Cheers,

 

[Lionel Thiry]

Trans a écrit :

Hi Ross, actually as Florian recently taught me, *obj works for any
object with #to_ary defined --if that is what you mean.

T.

AFAIK may change in ruby2.

 

[David A. Black]

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This message is in MIME format. The first part should be readable text,
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Hi --

Trans a =E9crit :

AFAIK may change in ruby2.

As Gary says it's actually to_a, not to_ary -- and I think it will
probably still work in 2.x, because Enumerable#to_a is explicitly
defined (not the soon-to-disappear default to_a for all objects).


David

--=20
David A. Black
(e-mail address removed)
--8323328-248990591-1133437847=:698--
--8323328-248990591-1133437847=:698--

 

[Lionel Thiry]

David A. Black a écrit :

Hi --




As Gary says it's actually to_a, not to_ary -- and I think it will
probably still work in 2.x, because Enumerable#to_a is explicitly
defined (not the soon-to-disappear default to_a for all objects).


David

Mmm, I remember Matz wonders about possible changes in the way the array
expansion operator * could work. He wonders if he should differentiate
array [a,b,c] and list a,b,c or not. Until decided, I keep in mind that
the way *args works may change in ruby2.

 

[James Edward Gray II]

On another note, though, I also found out that calling amethod
(*args) works with anything with 'each' (any Enumerable?), which
made me smile. It was the post about ranges that made me get that

Actually * looks for a to_a.

James Edward Gray II

 

[Brian Buckley]

Actually * looks for a to_a.

Does calling amethod(*x) have the same meaning as calling
amethod(x.to_a)? If is it what is the benefit of using the (less
clear) first way?

Brian Buckley

 

[Ross Bamford]

Actually * looks for a to_a.

James Edward Gray II

I was pretty surprised it worked for non-arrays to be honest, so I
didn't dare imagine it might be even _more_ flexible. Ruby just keeps on
getting better the more I get to know it - I've not been so pleasantly
surprised, so often, for a very long time...

Cheers,

 

[David A. Black]

Hi --

Does calling amethod(*x) have the same meaning as calling
amethod(x.to_a)? If is it what is the benefit of using the (less
clear) first way?

They're not the same. * is actually a unary unnary operator:

def x(*args)
p args
end

a = [1,2,3]
x(a) # [[1,2,3,]]
x(*a) # [1,2,3]


David

 

[Ross Bamford]

Does calling amethod(*x) have the same meaning as calling
amethod(x.to_a)? If is it what is the benefit of using the (less
clear) first way?

Brian Buckley

It 'unwraps' a supplied [anything] to multiple declared arguments. Imagine:

def amethod(one,two,three)
puts one, two, three
end

If you call that with:

amethod((1..3).to_a)

you'll get an error, because you only supplied one argument - the array.
If you specify the '*', however:

amethod(*(1..3))

The range first gets converted to an array with to_a, and then that is
expanded into the method's argument list.

You can double-check by specifying either 1..2 or 1..4, which gives an
ArgumentError.

 

[Brian Buckley]

a =3D [1,2,3]

x(a) # [[1,2,3,]]
x(*a) # [1,2,3]

x(*a) # [1,2,3]
x(a.to_a) # also [1,2,3]

But when might the 1st way (using the unary operator) be preferred to
the more explicit 2nd way?

Brian Buckley

 

[Brian Buckley]

But when might the 1st way (using the unary operator) be preferred to

the more explicit 2nd way?

Oops. Scratch that last question.

 

[David A. Black]

Hi --

a = [1,2,3]
x(a) # [[1,2,3,]]
x(*a) # [1,2,3]

x(*a) # [1,2,3]
x(a.to_a) # also [1,2,3]

But when might the 1st way (using the unary operator) be preferred to
the more explicit 2nd way?

I did leave off the to_a, though array.to_a is a no-op so it shouldn't
matter.

More to the point: what version of Ruby are you using? Here's the
output with 1.8.3:

$ cat args2.rb
def x(*args)
p args
end

a = [1,2,3]
x(a.to_a)
x(*a)

$ ruby -v args2.rb
ruby 1.8.3 (2005-09-21) [powerpc-darwin8.3.0]
[[1, 2, 3]]
[1, 2, 3]


David

 

[Brian Buckley]

More to the point: what version of Ruby are you using? Here's the

output with 1.8.3:

I am an older version (1.8.2) but I am getting the same result as you.
I didn't realize you'd intentionally omitted to noop to_a. That and
with Ross's explanation, now I get it.

 

[Daniel Schierbeck]

As Gary says it's actually to_a, not to_ary

#to_ary is called first; if it doesn't exist #to_a will be called.

 

[David A. Black]

Hi --

#to_ary is called first; if it doesn't exist #to_a will be called.

Whoops -- I got a false negative on a (flawed) little test I ran.


David

 

[Hal Fulton]

Actually * looks for a to_a.

I always thought it looked for to_ary... now someone says it looks
first for to_ary, then to_a.

And I had no idea that it would work with just #each defined.

"Curiouser and curiouser," said Alice.


Hal