From: Stefan Lang <perfectly.normal.hacker@...>
Date: 2009-01-22T06:09:39+09:00
Subject: Re: String doesnt auto dup on modification

2009/1/21 RK Sentinel <sentinel.2001@gmx.com>:
> I'm writing my first largeish app. One issue that gets me frequently is
> this:
>
> I define a string in one class. Some other class references it, and
> modifies it. I (somehow) expected that when another referer modifies the
> reference, ruby would automatically dup() the string.
>
> Anyway, through trial and error, I start dup()'ing strings myself. I am
> aware of freeze().
>
> But would like to know how others handle this generally in large apps.
>
> - Do you keep freezing Strings you make in your classes to avoid
> accidental change
>
> - Do you habitually dup() your string ?
>
> Is there some clean way of handling this that I am missing.

This is a well known "problem" with all languages that
have mutable strings. The solution is simple:

* Use destructive string methods only after profiling has shown
  that string manipulation is the bottleneck.

* Don't mutate a string after passing it across encapsulation
  boundaries.

Freezing certain strings can be beneficial in the same way
assertions are, habitually duping strings is a bad practice, IMO.

Stefan