Class families (#200)

* Warning for uninitialized storage

* Drop free functions, add __module__ and __all__

* Fix a few more missing __module__s

* Clean up __all__

* Remove .reduce and .project from cpp class

* Move Axis repr to Python and add transforms

* Lookup for transforms works

* Using repr from Python for Histogram

* Use Boost.Histogram << as repr for cpp.histogram

* Helpful error when C++ code not built

* Use register for Axes

* Use simpler storage scheme

* Remove final _to_ function

* CPP histogram returns CPP axis now

* Revamp decorator system, now could be useful in other packages

* Adding subclassing test

* Adding Storage/Transforms to the register system

* Simplify: no longer require @register for direct subclasses

* Unicode strings in repr on Python 2 (fix test)

* Simplify use of _compute_common_index

* Drop a few extra __module__ sets that were superfluous

* Fix __module__ on accumulators and slicing

Author: henryiii

boost_histogram/__init__.py

@@ -1,16 +1,43 @@
 from __future__ import absolute_import, division, print_function
 
+# Sadly, some tools (IPython) do not respect __all__
+# as a list of public items in a module. So we need
+# to delete / hide any extra items manually.
 del absolute_import, division, print_function
 
+__all__ = (
+    "Histogram",
+    "axis",
+    "storage",
+    "accumulators",
+    "algorithm",
+    "utils",
+    "numpy",
+    "loc",
+    "rebin",
+    "sum",
+    "underflow",
+    "overflow",
+    "__version__",
+)
+
+
+try:
+    from . import _core
+except ImportError as err:
+    err.msg += (
+        "\nDid you forget to compile? Use CMake or Setuptools to build, see the readme"
+    )
+    raise err
+
+
 from ._internal.hist import Histogram
-from . import axis, storage, accumulators, algorithm, numpy
+from . import axis, storage, accumulators, algorithm, utils, numpy
 from .tag import loc, rebin, sum, underflow, overflow
+
 from .version import __version__
 
 # Workarounds for smooth transitions from 0.5 series. Will be removed after 0.6.
-histogram = Histogram
-
-from .version import __version__
 
 from .tag import project