Re: *WHY* does this not work?

On Tue, Aug 9, 2011 at 1:52 PM, serialhex <[e-mail]> wrote:

> ok, so code:
>
> str = 'foo'
> => "foo"
> str.each_char do |c|
>  c = 'x'
> end
> => "foo"
>
> WHY does str == 'foo' still?? i would expect it to be 'xxx'!  this makes no
> sense, and is *QUITE* annoying...  i end up having to do things like this:
>
>
There are two reasons.
1) `c` is a variable. When you say `c = 'x'`, you are updating the object
that the variable c is pointing to, not invoking some sort of setter on the
string you are iterating over (which _is_ what you are doing in the array
example when you invoke the #[]= method).

2) Even if you were able to actually change the string, ie using `c.replace
'x'` rather than `c = x`, it wouldn't matter, because the char that `c` is
pointing to is a completely different string than `str`.



I don't know what you're trying to do, so I can't suggest a better solution,
but there is a way to do what you are asking using `String#gsub!`
str = "abc"
str.gsub!(/./) { |char| 'x' }
str # => "xxx"



> ... i CAN'T do things like that for a string because it dsn't seem to do
> that, but for an array i'd have to:
>
> ary = ['f', 'o', 'o']
> => ["f", "o", "o"]
> ary.each_index do |i|
>  ary[i] = 'x'
> end
> => ["x", "x", "x"]
>
> GAH!!! least surprise??  least surprise my FOOT!!!  even if there was a
> *.each! method to do that i would be fine, *that* would be ok, none of this
> 'get the index and then do what you need to do and *THEN* set the stupid
> block variable.... GRRRRRR!!!!
>
>
Try `Array#map!`

ary = ['f', 'o', 'o']
ary.map! { |char| 'x' }
ary # => ["x", "x", "x"]