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[dsimcha]

== Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s article

> If anyone wants to try it, I'm pasting the draft version of Appender
> from std.array below.
> Andrei

One comment:  Part of the reason why ~= is slow is that for anything other than a
tiny array, the array doesn't expand geometrically.  It expands a memory page at a
time.  You can see this by printing the capacity of an array as it is expanded,
using this trivial program:

import std.stdio, std.gc;

void main () {
    uint[] foo;
    size_t oldCapacity;
    foreach(i; 0..100_000) {
        foo ~= 1;
        if(capacity(foo.ptr) != oldCapacity) {
            writeln(capacity(foo.ptr));
            oldCapacity = capacity(foo.ptr);
        }
    }
}

This means that, even with cached capacity, appends are worse than amortized O(1).
 On the other hand, sometimes space is more important than speed.  Maybe how this
memory allocation is done could be a ctor parameter, with the default being geometric.