From: Emmanuel Touzery <emmanuel.touzery@...>
Date: 2003-06-03T16:35:11+09:00
Subject: Re: case of sub! not working



> Hi,
>
> In message "Re: case of sub! not working"
>     on 03/06/03, Ian Macdonald <ian@caliban.org> writes:
>
> |> ENV is not exactly a Hash, but a singleton that behaves kinda like one.
> |> Apparently, one difference is that ENV[key] returns a copy of the
value.
> |> (In hash.c, you can verify this by seeing that rb_f_getenv() calls
> |> rb_str_new2 or rb_tainted_str_new2 to generate the return value.)
> |
> |Thanks for the explanation. This definitely violates the principle of
> |least surprise, however, and I consider it a bug. At the very least, it
> |should go into the documentation, including the FAQ.
>
> Never say that.  You had two assumptions
>
>   * sub! to modify the receiver in-place
>
>   * when you modify the string from ENV in-place, the value of the
>     environment variable changes automagically.
>
> The former assumption is valid, the latter is not.  And it costs very
> much to satisfy your expectation.
>
> But I agree with putting it in the FAQ, for people fall into the same
> trap.

how about making the interpreter running a $ENV.freeze at the beginning of
the program?
if the variable can't be modified (somehow), it'd be more intuitive if it's
read-only, or do i miss something?

emmanuel