PythonInterface casting for workspaces can't work with multiple inheritance, e.g IMaskWorkspace

[Martyn Gigg]

It was found while trying to implement #8943 that the automatic downcast of DataItem pointers when returning to Python doesn't work for objects that multiple inherit from several interfaces.

The current mechanism tries to determine the required Python class automagically but fails in these types of circumstance and due to how boost python works it can't be made to work.

This ticket will be about implementing a simpler solution than the auto casting. It will simply have a C++ map of string IDs to the C++ types that they should be exposed as when returned to Python. This will also allow us more flexibility in choosing what is returned.

[Martyn Gigg]

Remove old DowncastReturnedValue policy

It is replaced by ToWeakPtrWithDowncast & ToSharedPtrWithDowncast policies. The DowncastRegistry now maps DataItem::id strings to the interfaces classes that the DataItem obejects should be cast to when returning to Python Refs #8996

Changeset: 7313892660ddffe54352312b34948f8762377c9e

[Martyn Gigg]

Add a class to do all required registration for a DataItem subclass

It encapsulates everything required for pointer & downcast registration. Refs #8996

Changeset: 284788c3eb7910c752e8b4c43700226b05668f4e

[Martyn Gigg]

Remove the SharedPtrToPython macro.

It's unnecessary now as a direct boost::python call is clearer. Refs #8996

Changeset: 9469062edce0f4e3ffdd8e540e370cdb4e6ef198

[Martyn Gigg]

Remove DowncastReturnedValue from CMakeLists.txt

Refs #8996

Changeset: 0b4e5a52ef0c69c243dabb11a5344bcb59defb16

[Martyn Gigg]

Remove SharedPtrToPythonMacro from CmakeLists

Refs #8996

Changeset: f0a5a15b980500af912c6be9bd6d283a3eff1f64

[Martyn Gigg]

Refactor TypeRegistry to use a static class like the DowncastRegistry.

Refs #8996

Changeset: 0049beee16e6bb80862ef751b35495b0f834ee05

[Martyn Gigg]

Use new RegisterDataItemInterface class in place of macro

This now does the required additional registration for workspace types. Refs #8996

Changeset: ab9b044da683d3cfd0edb08020516af2190dedda

[Martyn Gigg]

Put back ADS raising KeyError rather than RuntimeError.

Refs #8996

Changeset: 392baa6fa3d8086141f1d67d792b7ce485e921bf

[Martyn Gigg]

Remove redundant code.

The SingleValueTypeHandler is now replaced everywhere by the TypedPropertyValueHandler. Refs #8996

Changeset: 5890b30da2ed9894fc06a8b5ee965b7a585e7a0a

[Martyn Gigg]

Tidy up PropertyWithValueFactory.

Remove macro usage and store shared_ptrs in map. Refs #8996

Changeset: d6c7c574674a2a7d95c2a93a1661eb7748db671a

[Martyn Gigg]

Dynamic cast when setting property from weak_ptr in python

This accounts for multiple-inheritance scenarios where a static_cast cannot detect that a cast is actually possible. Refs #8996

Changeset: 824298bc8a4b921cad3ff8b96fc157b0853c0cbc

[Martyn Gigg]

Add missing include for exception type.

Refs #8996

Changeset: 56be19ec69a53961cf7c34dce1fceb9fa27a5e7f

[Martyn Gigg]

Fix type for map insertion in TypeRegistry

Refs #8996

Changeset: c1b0b91fa3f5ac6f971b4f2f0b87eecc328708e4

[Martyn Gigg]

Fix Python function tests.

They were calling getProperty().value on a non-child algorithm where the internal workspace pointer is null. Refs #8996

Changeset: 2adda60aceb1c8b21a58d4594c875e3fe34af5d6

[Martyn Gigg]

Check for null pointer in DowncastingPolicies.

The return is now just the PyNone object. Refs #8996

Changeset: 550d68c35e0d91e4801116927787f5860d4bb0ec

[Martyn Gigg]

Fix passing weak_ptrs back to C++ from Python layer.

Refs #8996

Changeset: 096a518959b38f1b0fff7ba2a0c368e66acd4666

[Martyn Gigg]

Rename RegisterDataItemInterface to DataItemInterface.

Refs #8996

Changeset: 52351aeac24d6586e154405581ef0192c3d76878

[Martyn Gigg]

Remove a macro in favour of direct WorkspacePropertyExporter usage.

Refs #8996

Changeset: 77a48d6e6bbd61073ba6e8b3d880b65c7e619913

[Martyn Gigg]

Remove another macro in favour of a templated static class

Refs #8996

Changeset: ad5b4f43978a0f21160230f38138c92c2089f023

[Martyn Gigg]

Remove another macro in a header in favour of template class

Refs #8996

Changeset: eabcca5f7d7d218cbd27a114b866f0f128a8591c

[Martyn Gigg]

Remove a pointless namespace declaration.

Refs #8996

Changeset: 58c9ccede9184b3f855c8180e1d35a7fd0fe8fd1

[Martyn Gigg]

An ugly cast for interfaces that don't inherit from DataItem.

Refs #8996

Changeset: 2da84ba1fbf8ef799272c6a7f573f6352410fa1d

[Martyn Gigg]

Change header reference in CMakeLists file.

Refs #8996

Changeset: 70e30d30ae332e1e7fce24b69d94116c6ba64b21

[Martyn Gigg]

Kill a compiler warning about unused exception variable.

Refs #8996

Changeset: 5a99e082157b0d7c4fb4c421397659d324aa8de6

[Martyn Gigg]

Branch: feature/8996_python_dataitem_casting

Tester: These changes are required to be able to correctly cast to IMaskWorkspace when it is exported in #8943. There should be no visible changes in usage from Python and the only 3 tests that were changed were altered to remove redundant lines. Obviously the unit & system tests should be passing in all places without any other changes.

Several places in the code were tidied up along the way to reduce the number of macros in headers and to make the TypeRegistry & DowncastRegistry more consistently designed.

[Peter Peterson]

I'm having a hard time verifying this one as I merged this into master, then the masking one, and still no masking properties on a MaskWorkspace.

[Martyn Gigg]

So I've completely restructed the casting stuff so the masking one shouldn't even merge cleanly when this goes in.

Getting IMaskWorkspace will now require a few extra lines in the IMaskWorkspace.cpp export file

using Mantid::PythonInterface
DataItemInterface<IMaskWorkspace>()
  // map IDs to this interface
  .castFromID("MaskWorkspace")
;

along with removing the id "MaskWorkspace" from the list in the PythonInterface/mantid/api/src/Exports/MatrixWorkspace.cpp at the bottom, remembering to update the NUM_IDS counter.

[Anders Markvardsen]

I am going to struggle fitting this one in today. If this here by Monday will look at it agains

[Alex Buts]

Its nice ticket which I would be interested to learn but it needs some time to spend on and unfortunately more urgent issue come, which I have to deal with.

[Owen Arnold]

Everything looks to be in order. Simple solution. Lot of additional changes required to make it happen.

[Owen Arnold]

Merge remote-tracking branch 'origin/feature/8996_python_dataitem_casting'

Full changeset: ​05fd06fca4923e9aca9d68fefb91bab29948bd32

[Stuart Campbell]

This ticket has been transferred to github issue ​9839