Pop quiz [memory usage]

davidl davidl at nospam.org
Sat Jun 6 22:20:49 PDT 2009


在 Sun, 07 Jun 2009 12:59:39 +0800,Sean Kelly <sean at invisibleduck.org>  
写道:

> Steve Schveighoffer wrote:
>> On Sat, 06 Jun 2009 12:03:03 -0700, Sean Kelly wrote:
>>
>>> bearophile wrote:
>>>> Sean Kelly:
>>>>> Particularly in D2 where append
>>>>> operations on arrays are probably less common as a result of string
>>>>> being invariant.
>>>> They aren't much common maybe because they are currently dead-slow.
>>>> Appending to an immutable string is a common operation. But I guess
>>>> Array appenders will get more common...
>>> Yes but appending to an immutable string is never performed in place,
>>> which is the only time the extra space reserved by newCapacity matters.
>>>   I suspect the memory wasted by newCapacity is more of an issue than
>>> any time savings it provides.
>>  What gave you that idea?
>>  void main()
>> {
>>   auto str1 = "hello".idup;
>>   auto str2 = str1;
>>   str1 ~= "world";
>>   assert(str1.ptr == str2.ptr);
>> }
>
> auto str1 = "hello".idup;
> auto str2 = str3 = str1;
> str2 ~= " world";
> str3 ~= " garbage";
>
> Doesn't seem terribly safe to me.

Oh, file a bug report! you find the bug!

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