how to be faster than perl?

[Frits van Bommel]

Boris Bukowski wrote:
> currently I am testing D for log processing.
> My perl script is more than ten times faster than my D Prog.
> How can I get Lines faster from a File?

I don't think the file handling is your problem.

> ---snip---
> private import std.stream;
> private import std.stdio;
> private import std.string;
> 
> void main (char[][] args) {
>         int c;
>         Stream file = new BufferedFile(args[1]);
>         foreach(ulong n, char[] line; file) {
>                 if(std.regexp.find(line, "horizontal") > -1){
>                         c++;
>                 }
>         }
> 
>         writefln("%d", c);
> 
> }

std.regexp.find instantiates a RegExp object, compiles the regex and 
uses it once, then deletes it. This is fine for one-time searches, but 
if you're using it for each line of a file, you're allocating and 
deleting an object for each line and performing unnecessary work to 
recompile the same regex over and over.

Try something like this instead:
-----
// (untested code)
auto re = new RegExp("horizontal");
foreach (ulong n, char[] line; file) {
     if (re.find(line) > -1) {
// ...
-----
as the start of your foreach loop.
That should be faster.

I don't know how fast it'll be compared to Perl; I don't know anything 
about the relative performance of D vs. Perl regexes. (In fact, I hardly 
ever use regexes, and have never used Perl)