Array append performance

[superdan]

Benji Smith Wrote:

> Robert Jacques wrote:
> > On Sun, 24 Aug 2008 22:14:36 -0400, bearophile 
> > <bearophileHUGS at lycos.com> wrote:
> >> And, why the stride? I presume it's useful if you want a 2D matrix.
> > 
> > Yes, stride is a key enabler for integrating 2D/3D/nD matrices with 
> > built-in arrays.
> > Other pros:
> > - Fast O(1) reversing of an array. Looping through an array in reverse 
> > was a common enough operation to create an additional keyword and 
> > language feature (foreach_reverse) specifically for it.
> > - Slicing out a struct element. i.e. slice the red channel out of an 
> > image or the first name from an Employee array.
> > - Accessing every Nth element. This is a common MATLAB operation and 
> > often used in visualization (i.e. a quick and simple resolution 
> > adjustment for a line plot). Also, some parallel algorithms benefit from 
> > interleaving data. This is a fairly standard multi-threading technique, 
> > particularly when processing data[x] may take longer than processing 
> > data[y] (though it's not the first thing I'd try).
> 
> That's very convincing. Seems like stride ought to be in there.
> 
> But it also got me thinking about what other 4-byte value could be 
> stuffed into that extra space (satisfying the 16-bit alignment 
> requirement), and I can't help but yearn for hashcode memoization.
> 
> Strings are, arguably, the most common types of arrays in most programs. 
>   And strings are, arguably the most common key-type in associative 
> arrays. And every time you perform an associative array lookup, you have 
> to re-compute the hashcode (which is silly for immutable strings, since 
> the hashcode can't ever change).
> 
> In languages where Strings are objects (please!!! please, Walter!!!)

ok, i'll bite. what exactly are you so desperately asking for?