feat: psp gala compat (#266)

Signed-off-by: nstarman <[email protected]>

src/galax/coordinates/__init__.py

@@ -7,11 +7,15 @@
 from lazy_loader import attach_stub
 
 from galax.setup_package import RUNTIME_TYPECHECKER
+from galax.utils._optional_deps import HAS_GALA
 
 __getattr__, __dir__, __all__ = attach_stub(__name__, __file__)
 
 # runtime type checking
 install_import_hook("galax.coordinates", RUNTIME_TYPECHECKER)
 
+if HAS_GALA:
+    from . import _compat  # noqa: F401
+
 # Clean up the namespace
-del install_import_hook, attach_stub, RUNTIME_TYPECHECKER
+del install_import_hook, attach_stub, RUNTIME_TYPECHECKER, HAS_GALA

src/galax/coordinates/_compat.py

@@ -0,0 +1,25 @@
+"""Compatibility.
+
+TODO: make all the `gala` compat be in a linked package.
+
+"""
+
+__all__: list[str] = []
+
+try:  # TODO: less hacky way of supporting optional dependencies
+    import pytest
+except ImportError:
+    pass
+else:
+    _ = pytest.importorskip("gala")
+
+import gala.dynamics as gd
+from plum import conversion_method
+
+import galax.coordinates as gcx
+
+
+@conversion_method(type_from=gd.PhaseSpacePosition, type_to=gcx.PhaseSpacePosition)  # type: ignore[misc]
+def gala_psp_to_galax_psp(obj: gd.PhaseSpacePosition, /) -> gcx.PhaseSpacePosition:
+    """`gala.dynamics.PhaseSpacePosition` -> `galax.coordinates.PhaseSpacePosition`."""
+    return gcx.PhaseSpacePosition(q=obj.pos, p=obj.vel, t=None)

src/galax/dynamics/__init__.py

@@ -4,10 +4,14 @@
 from lazy_loader import attach_stub
 
 from galax.setup_package import RUNTIME_TYPECHECKER
+from galax.utils._optional_deps import HAS_GALA
 
 with install_import_hook("galax.dynamics", RUNTIME_TYPECHECKER):
     __getattr__, __dir__, __all__ = attach_stub(__name__, __file__)
 
+if HAS_GALA:
+    from . import _compat  # noqa: F401
+
 
 # Cleanup
-del install_import_hook, RUNTIME_TYPECHECKER
+del install_import_hook, RUNTIME_TYPECHECKER, HAS_GALA

src/galax/dynamics/_compat.py

@@ -0,0 +1,31 @@
+"""Compatibility.
+
+TODO: make all the `gala` compat be in a linked package.
+
+"""
+
+__all__: list[str] = []
+
+try:  # TODO: less hacky way of supporting optional dependencies
+    import pytest
+except ImportError:
+    pass
+else:
+    _ = pytest.importorskip("gala")
+
+import gala.dynamics as gd
+from plum import conversion_method
+
+import galax.dynamics as gdx
+
+
+@conversion_method(type_from=gd.Orbit, type_to=gdx.Orbit)  # type: ignore[misc]
+def gala_orbit_to_galax_orbit(obj: gd.Orbit, /) -> gdx.Orbit:
+    """`gala.dynamics.Orbit` -> `galax.dynamics.Orbit`."""
+    return gdx.Orbit(q=obj.pos, p=obj.vel, t=obj.t)
+
+
+@conversion_method(type_from=gd.MockStream, type_to=gdx.MockStream)  # type: ignore[misc]
+def gala_mockstream_to_galax_mockstream(obj: gd.MockStream, /) -> gdx.MockStream:
+    """`gala.dynamics.MockStream` -> `galax.dynamics.MockStream`."""
+    return gdx.MockStream(q=obj.pos, p=obj.vel, release_time=obj.release_time)