remove force imports

.conda/meta.yaml

@@ -19,14 +19,8 @@ build:
 
 
 requirements:
-  build:
-    - "python>=3.8"
-    - setuptools
-    - "ase>=3.22"
-    - pip
   host:
     - "python>=3.8"
-    - "ase>=3.22"
     - pip
   run:
     - "python>=3.8"

sparc/__init__.py

@@ -1,5 +1,35 @@
-from .io import read_sparc, write_sparc
-from .io import register_ase_io_sparc
-from .calculator import SPARC
+"""Initialization of sparc-x-api
 
-register_ase_io_sparc()
+For submodules like download_data and api, ase / numpy may be ignored,
+and run using standard python libaries. This may be useful for cases like
+conda build and CI where not all dependencies are present
+"""
+
+def _missing_deps_func(*args, **kwargs):
+    raise ImportError("Importing fails for ase / numpy!")
+
+class SPARCMissingDeps:
+    def __init__(self, *args, **kwargs):
+        raise ImportError("Cannot initialize sparc.SPARC because the required dependencies (ase and numpy) are not available.")
+
+    def __getattr__(self, name):
+        raise ImportError(f"Cannot access '{name}' on sparc.SPARC because the required dependencies (ase and numpy) are not available.")
+try:
+    import ase
+    import numpy
+    _import_complete = True
+except ImportError:
+    _import_complete = False
+
+if _import_complete:
+    from .io import read_sparc, write_sparc
+    from .io import register_ase_io_sparc
+    from .calculator import SPARC
+    register_ase_io_sparc()
+else:
+    # If importing is not complete, any code trying to directly import
+    # the following attributes will raise ImportError
+    read_sparc = _missing_deps_func
+    write_sparc = _missing_deps_func
+    SPARC = SPARCMissingDeps
+