Phobos addition formal review: std.experimental.allocator

[Andrei Alexandrescu via Digitalmars-d]

On 6/12/15 4:08 AM, Dicebot wrote:
> Small tip for reviewers: there are quite many modules in proposed
> package but majority is actual allocator implementation. I'd suggest to
> start investigating sources/documentation starting from
> http://erdani.com/d/phobos-prerelease/std_experimental_allocator.html
> and
> http://erdani.com/d/phobos-prerelease/std_experimental_allocator_building_blocks.html
> while using
> http://erdani.com/d/phobos-prerelease/std_experimental_allocator_showcase.html
> as reference for "highlight" examples.

A few more words on that:

Think of std.experimental.allocator as a three-layered cake:

* An untyped layer, dealing exclusively in void[], and where all action 
is happening. That's where work is getting done, and also where assembly 
of various custom allocators happens. Best entry point for that is 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator_building_blocks.html, 
which describes this layer's design and links to all untyped components.

* A statically-typed layer, which takes types from the user and gives 
back typed memory. There are two good entry points here: 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator.html 
contains generic routines for creating and destroying typed objects 
using any untyped allocator: make, dispose, etc. There is also assembly 
at this level, i.e. deciding to use different heaps for shared vs. 
unshared data: 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator_typed.html 
(this is particularly beautiful or awful, depending).

* A dynamicaly-typed layer that allows the user to swap allocators at 
runtime. This is embodied in IAllocator, CAllocatorImpl, theAllocator, 
and processAllocator.


Thanks in advance for reviewing this!

Andrei