From: "Matthias Wächter" <matthias@...>
Date: 2008-02-22T19:46:11+09:00
Subject: Re: What does *args do?

Mark,

thanks for your perfect explanation of the problem, you clearly make my point. :)

Mark Bush wrote:
> The problem is: what is the value of a after:
> 
> a, b, c = d
> 
> ?
> The answer is: it depends.  If d is an array, then a becomes d[0], 
> otherwise a becomes d.  Since you can write:
> 
> a, b, c = "hi", "hello", "wassa"
> 
> setting each value, and:
> 
> a, b, c = "hi"

To make inconsistencies even more stupid, we could specify that

a,b,c,d,e = "aeiou"

results in a=="a", b=="e", c=="i", d=="o", e=="u".

or

a,b,c,d = 5

could be interpreted as a bit-wise split assignment such that a==0, b==1, c==0, d==1. I see no point in allowing an array to be treated specially, even more so as there is the one-character splat operator available.

> Further, consider this example:
> 
> a = [[1, 2, 3]]
> b, c, d = *a
> 
> What is the value of b?  Since the multiple assignment is "equivalent" 
> to:
> 
> b, c, d = [1, 2, 3]
> 
> it would seem that the way arrays automagically expand would result in b 
> becoming 1, but actually b becomes the array [1, 2, 3] meaning that 
> automagic expansion is not happening.  So even the inconsistency is 
> inconsistent!

Yeah, thanks for this perfect example of the matter!

> The semantics of assignment should not change just because the class of 
> something on the rhs changes.

My words.

Was this discussed already so that we know what Matz thinks about it, or should we bring this topic up on ruby-core?

- Matthias