ruby - Change values of variables in array -

i have array made variables, , want perform same operation on each, , store result in original variable:

(one, two, three) = [1, 2, 3]  [one, two, three].map!{|e| e += 1} # => [2, 3, 4]   # but: [one, two, three] # => [1, 2, 3]  # have to:  (one, two, three) = [one, two, three].map{|e| e += 1} # => [2, 3, 4]   [one, two, three] # => [2, 3, 4] 

this doesn't seem "right way" it, i'm not managing find "right way". have vague ideas what's going on, i'm not sure, explanation appreciated.

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my actual use case i've got named parameters , i'm e = file.new(e) if e.is_a? string

numbers (such fixnum) in ruby immutable. cannot change underlying value.

once assign one = 1, not possible change value of one without new assignment. when one += 1. assigning new value 2 variable one; it's whole new object.

you can see more looking @ object_id (a.k.a. __id__):

one = 1 1.object_id     # => 2 one.object_id   # => 2 1 += 1 one.object_id   # => 5 2.object_id     # => 5 

now in array#map! statement, you're not changing one object. reference object stored in array; not actual variable. when enumerate map!, object returned block stored in internal reference location @ same position. think of first pass on map! similar following:

one = 1 one.object_id     # => 2  arr = [one]  arr[0].object_id  # => 2  arr[0] += 1   # re-setting object @ index 0               # not changing original `one`'s value  arr[0]            # => 2 arr[0].object_id  # => 5  1               # => 1 one.object_id     # => 2 

since these fixnum objects immutable, there no way change value. why have de-reference result of map original values:

(one, two, three) = [1, 2, 3] one.object_id      # => 3 two.object_id      # => 5 three.object_id    # => 7  (one, two, three) = [one, two, three].map{|e| e += 1} one.object_id      # => 5 two.object_id      # => 7 three.object_id    # => 9