Does Struct#to_a guarantee the order of the values

ruby-talk
1

The Pickaxe implies this, but I thought it would be wise to make
sure…

Suppose I use Struct to generate a class and then create an instance
of the class like this:

F = Struct.new(‘F’, :x, :y, :z)
f1 = F.new(1,2,3)

Can I be sure that f1.to_a returns [1,2,3] and never [3,2,1] or
[2,3,1]? That is, does F#to_a guarantee that the values in the array
are in the same order that the instance variables were specified to
Struct.new?

Same for F#members. Will the strings in the array be in the same order
that the symbols were specified to Struct.new?

2

Hi,

···

In message “Does Struct#to_a guarantee the order of the values” on 03/02/22, Tim Hunter Tim.Hunter@sas.com writes:

Suppose I use Struct to generate a class and then create an instance
of the class like this:

F = Struct.new(‘F’, :x, :y, :z)
f1 = F.new(1,2,3)

Can I be sure that f1.to_a returns [1,2,3] and never [3,2,1] or
[2,3,1]? That is, does F#to_a guarantee that the values in the array
are in the same order that the instance variables were specified to
Struct.new?

Same for F#members. Will the strings in the array be in the same order
that the symbols were specified to Struct.new?

Yes. Struct is array (not hash) with symbolic index.

						matz.
3

Thanks, matz!

···

On Sat, 22 Feb 2003 13:58:24 +0900, Yukihiro Matsumoto wrote:

Hi,

In message “Does Struct#to_a guarantee the order of the values” > on 03/02/22, Tim Hunter Tim.Hunter@sas.com writes:

Suppose I use Struct to generate a class and then create an instance of
the class like this:

F = Struct.new(‘F’, :x, :y, :z)
f1 = F.new(1,2,3)

Can I be sure that f1.to_a returns [1,2,3] and never [3,2,1] or [2,3,1]?
That is, does F#to_a guarantee that the values in the array are in the
same order that the instance variables were specified to Struct.new?

Same for F#members. Will the strings in the array be in the same order
that the symbols were specified to Struct.new?

Yes. Struct is array (not hash) with symbolic index.

  					matz.