Wrapped design

[henryiii]

This changes the design to hold an internal object, and users only interact with the Python classes. Closes #180. Proposed by @HDembinski some time ago.

File layout changes

The C++ core is now named _core, and non-public Python parts are in _internal. The cpp module is new (see below). AxesTuple is in now in _internal/axestuple.py, _utils is now _internal/kwargs.py (the old meta utils are gone, no longer needed). uhi.py is now tag.py.

Histogram design:

• BaseHistogram: Shared interface
  • BoostHistogram: Mimics the C++ interface as closely as possible. Even has __call__!
  • Histogram: The default interface, with Pythonizations. Caches the axes tuple.

You can convert between the two, or add a new class. If you do:

import boost_histogram.cpp as bh

You will now be working with BoostHistograms instead of Histograms. (closes #155)

Axes design:

There is a base class Axis, along with Regular, etc. for the 4 types. The axis object is stored in _ax. The function forms are now class methods, regular.sqrt for example (they are still available as regular_sqrt for the moment, as well). A helper function internally knows how to convert an axis object into the correct Axis class, and is used when pulling an axis from a histogram.

General changes

The underscores on some C++ parts have been removed. An underscore in the C++ bindings indicates that something is different than the C++ code. The C++ _core objects have been stripped down a little, and exactly mimic C++ where possible (.rank() is a function, etc). The Pythonisation now happens in Histogram. Axes tuples have functions now too (closes #176), and are finally tested.

Also, more docs present, closes #174.

[henryiii]

Let's go ahead and merge this into develop, and review/changes can be PRs. I need this in so I work on the next set of changes as new branches on the flight to Australia. Anything here can be reverted/modified in develop if needed.

[henryiii]

(Actually, @HDembinski, to make it easier to review, I'll leave this open, but build branches off of it on the plane, but will need to merge before proceeding).

[henryiii]

Please raise issues if there are parts of the design that could be better! I've already been working off this, and it seems to be working pretty well.

[HDembinski]

No regular.sqrt. The transform should be a passed as a keyword to the regular class.

[HDembinski]

This is a change that slipped by me. I think we should not have these class methods, since people should use the transform keyword.