refactor: extend usage of the new on-demand-import mechanism to secon…

…d class optional deps

yt/data_objects/data_containers.py

@@ -22,6 +22,7 @@
     YTSpatialFieldUnitError,
 )
 from yt.utilities.object_registries import data_object_registry
+from yt.utilities.on_demand_imports import firefly_api
 from yt.utilities.parameter_file_storage import ParameterFileStore
 
 
@@ -782,18 +783,8 @@ def create_firefly_object(
             >>> reader.particleGroups[0].decimation_factor=100
             >>> reader.dumpToJSON()
         """
-
-        ## attempt to import firefly_api
-        try:
-            from firefly_api.particlegroup import ParticleGroup
-            from firefly_api.reader import Reader
-        except ImportError as e:
-            raise ImportError(
-                "Can't find firefly_api, ensure it "
-                "is in your python path or install it with "
-                "'$ pip install firefly_api'. It is also available "
-                "on github at github.com/agurvich/firefly_api"
-            ) from e
+        Reader = firefly_api.reader.Reader
+        ParticleGroup = firefly_api.particlegroup.ParticleGroup
 
         ## handle default arguments
         fields_to_include = [] if fields_to_include is None else fields_to_include

yt/startup_tasks.py

@@ -14,21 +14,24 @@
     signal_print_traceback,
 )
 from yt.utilities import rpdb
+from yt.utilities.on_demand_imports import mpi4py
 
 exe_name = os.path.basename(sys.executable)
 # At import time, we determined whether or not we're being run in parallel.
 def turn_on_parallelism():
+    """
+    Activate parallel capabilities.
+
+    Raises
+    ------
+    ImportError if mpi4py isn't installed.
+    """
     parallel_capable = False
-    try:
-        # we import this to check if mpi4py is installed
-        from mpi4py import MPI  # NOQA
-    except ImportError as e:
-        mylog.error(
-            "Warning: Attempting to turn on parallelism, "
-            "but mpi4py import failed. Try pip install mpi4py."
-        )
-        raise e
-        # Now we have to turn on the parallelism from the perspective of the
+
+    # check that mpi4py is correctly installed
+    mpi4py.MPI
+
+    # Now we have to turn on the parallelism from the perspective of the
     # parallel_analysis_interface
     from yt.utilities.parallel_tools.parallel_analysis_interface import (
         enable_parallelism,

yt/utilities/command_line.py

@@ -35,6 +35,7 @@
     YTUnidentifiedDataType,
 )
 from yt.utilities.metadata import get_metadata
+from yt.utilities.on_demand_imports import bottle
 from yt.visualization.plot_window import ProjectionPlot, SlicePlot
 
 # isort: off
@@ -1055,14 +1056,7 @@ def __call__(self, args):
         p.set_cmap("all", args.cmap)
 
         PannableMapServer(p.data_source, args.field, args.takelog, args.cmap)
-        try:
-            import bottle
-        except ImportError as e:
-            raise ImportError(
-                "The mapserver functionality requires the bottle "
-                "package to be installed. Please install using `pip "
-                "install bottle`."
-            ) from e
+
         bottle.debug(True)
         if args.host is not None:
             colonpl = args.host.find(":")

yt/utilities/on_demand_imports.py

@@ -60,18 +60,6 @@ def __getattr__(self, key):
             return self._submodules[key]
 
 
-# TEMP: these require special treatments
-__special_cases = [
-    # the following are currently not using the on-demand-imports mechanism
-    # and replace it with unnecessary special treatments
-    "bottle",
-    "firefly_api",
-    "mpi4py",
-    "resource",
-    "yt_astro_analysis",
-]
-
-
 if any(s in sys.version for s in ("Anaconda", "Continuum")):
     # conda distributions of cartopy don't have issues with the GEOS library
     # so we can keep the error message short
@@ -87,7 +75,9 @@ def __getattr__(self, key):
 
 targets = [
     "astropy",
+    "bottle",
     ("cartopy", _cartopy_instructions),
+    "firefly_api",
     "f90nml",
     # Breaking alphabetical ordering on purpose here.
     # Importing h5py before netCDF4 can lead to file lock errors
@@ -100,6 +90,7 @@ def __getattr__(self, key):
         "miniball",
         "This package can be installed from Pypi with\n`python -m pip install MiniballCpp`",
     ),
+    "mpi4py",
     "nose",
     "pandas",
     "pooch",

yt/utilities/parallel_tools/parallel_analysis_interface.py

@@ -18,6 +18,7 @@
 from yt.utilities.exceptions import YTNoDataInObjectError
 from yt.utilities.lib.quad_tree import QuadTree, merge_quadtrees
 from yt.utilities.logger import ytLogger as mylog
+from yt.utilities.on_demand_imports import mpi4py
 
 # We default to *no* parallelism unless it gets turned on, in which case this
 # will be changed.
@@ -86,12 +87,11 @@ def enable_parallelism(suppress_logging=False, communicator=None):
     """
     global parallel_capable, MPI
     try:
-        from mpi4py import MPI as _MPI
+        MPI = mpi4py.MPI
     except ImportError:
         mylog.info("mpi4py was not found. Disabling parallel computation")
         parallel_capable = False
         return
-    MPI = _MPI
     exe_name = os.path.basename(sys.executable)
 
     # if no communicator specified, set to COMM_WORLD

yt/utilities/rpdb.py

@@ -8,6 +8,7 @@
 from xmlrpc.server import SimpleXMLRPCServer
 
 from yt.config import ytcfg
+from yt.utilities.on_demand_imports import mpi4py
 
 
 class PdbXMLRPCServer(SimpleXMLRPCServer):
@@ -48,13 +49,11 @@ def rpdb_excepthook(exc_type, exc, tb):
     server.serve_forever()
     server.server_close()
     if size > 1:
-        from mpi4py import MPI
-
         # This COMM_WORLD is okay.  We want to barrierize here, while waiting
         # for shutdown from the rest of the parallel group.  If you are running
         # with --rpdb it is assumed you know what you are doing and you won't
         # let this get out of hand.
-        MPI.COMM_WORLD.Barrier()
+        mpi4py.MPI.COMM_WORLD.Barrier()
 
 
 class pdb_handler:

yt/visualization/mapserver/pannable_map.py

@@ -1,10 +1,10 @@
 import os
 from functools import wraps
 
-import bottle
 import numpy as np
 
 from yt.utilities.lib.misc_utilities import get_color_bounds
+from yt.utilities.on_demand_imports import bottle
 from yt.utilities.png_writer import write_png_to_string
 from yt.visualization.fixed_resolution import FixedResolutionBuffer
 from yt.visualization.image_writer import apply_colormap