Difference between is and ==

[Suliman]

> My interpretation of tdpl p57:
>
> 'is' compares for alias equality for arrays and classes.
> Otherwise they are the same.

So should next code have same behavior if I will use is instead 
of ==

import std.stdio;
import std.string;

void main()
{
	getchar();
}

void getchar()
{
	string x;
	if ((x = stdin.readln().chomp) == "q")
		writeln("it's is q");
	else
		writeln("Not q");
}

In case I am using is, I have never get first if expression is 
true.