GC question

[rikki cattermole via Digitalmars-d-learn]

On 05/02/2017 5:02 PM, thedeemon wrote:

snip

> It may look so from a distance. But in my experience it's not that bad.
> In most software I did in D it did not matter really (it's either 64-bit
> or short lived programs) and the control D gives to choose how to deal
> with everything makes it all quite manageable, I can decide what to take
> from both worlds and hence pick the best, not the worst.

The best of both worlds can be done quite simply.

Instead of a chain of input ranges like:

int[] data = input.filter!"a != 7".map!"a * 2".array;

Use:

int[] data;
data.length = input.length;

size_t i;
foreach(v; input.filter!"a != 7".map!"a * 2") {
	data[i] = v;
	i++;
}

data.length = i;

Of course this is dirt simple example, but instead look at it for e.g. a 
csv parser with some complex data structure creation + manipulation.

I have some real world code here[0] that uses it. Not only is there less 
allocations and uses the GC but also it ends up being significantly faster!

[0] 
https://gist.github.com/rikkimax/42c3dfa6500155c5e441cbb1437142ea#file-reports-d-L124