On Sunday, 8 April 2012 at 05:56:36 UTC, Andrei Alexandrescu
wrote:
Walter and I discussed today about using the small string
optimization in string and other arrays of immutable small
objects.
On 64 bit machines, string occupies 16 bytes. We could use the
first byte as discriminator, which means that all strings under
16 chars need no memory allocation at all.
Don't use the first byte. Use the last byte.
The last byte is the highest-order byte of the length. Limiting
arrays to 18.37 exabytes, as opposed to 18.45 exabytes, is a much
nicer limitation than making assumptions about the memory layout.
