[ruby-core:28476] Re: [Feature #905] Add String.new(fixnum) to preallocate large buffer

Hi,

2010/3/5 Kornelius Kalnbach <[e-mail]>:
> Doesn't Ruby allocate already using a "double memory if you run out"
> rule? That makes string concatenation (amortized) linear, even if the
> string must be moved in the memory.

Yes, it does.  This is why I think experiment is needed.

Because the suggested feature can be used to omit first some
expansions, it will actually reduce time.  But I guess if the
reduced time is not so much.


> Even with this API extension, we wouldn't have control over the
> generation of the string buffer in many use cases, as in Array#join,
> String#% or in literals using #{}. Its use would be limited to String#<<.

Absolutely.  The feature is hard to use.
Even if we pre-allocated a string, calling some method on the
string may shrink it.

I think we should call the feature just "optimization hint"
rather than API.  It is better to think the hint may be even
ignored.

-- 
Yusuke ENDOH <[e-mail]>