jmol: access files through features, for simpler configuration

Author: tornaria

src/sage/env.py

@@ -211,7 +211,7 @@ def var(key: str, *fallbacks: Optional[str], force: bool = False) -> Optional[st
 POLYTOPE_DATA_DIR = var("POLYTOPE_DATA_DIR")
 
 # installation directories for various packages
-JMOL_DIR = var("JMOL_DIR", join(SAGE_SHARE, "jmol"))
+JMOL_DIR = var("JMOL_DIR")
 MATHJAX_DIR = var("MATHJAX_DIR", join(SAGE_SHARE, "mathjax"))
 MTXLIB = var("MTXLIB", join(SAGE_SHARE, "meataxe"))
 THREEJS_DIR = var("THREEJS_DIR", join(SAGE_SHARE, "threejs-sage"))

src/sage/features/jmol.py

@@ -0,0 +1,43 @@
+import os
+
+from . import StaticFile
+
+
+class JmolDataJar(StaticFile):
+    r"""
+    A :class:`~sage.features.Feature` which describes the presence of
+    JmolData.jar in a few standard locations.
+
+    EXAMPLES::
+
+        sage: from sage.features.jmol import JmolDataJar
+        sage: bool(JmolDataJar().is_present())  # needs jmol
+        True
+    """
+
+    def __init__(self):
+        r"""
+        TESTS::
+
+            sage: from sage.features.jmol import JmolDataJar
+            sage: isinstance(JmolDataJar(), JmolDataJar)
+            True
+        """
+        from sage.env import SAGE_SHARE, JMOL_DIR
+
+        jmol_search_path = JMOL_DIR or (
+                os.path.join(SAGE_SHARE, "sagemath", "jmol"),
+                os.path.join(SAGE_SHARE, "jmol")
+                )
+
+        StaticFile.__init__(
+            self, name="jmol",
+            filename="JmolData.jar",
+            search_path=jmol_search_path,
+            spkg="jmol",
+            type="standard",
+            description="Java viewer for chemical structures in 3D")
+
+
+def all_features():
+    return [JmolDataJar()]

src/sage/interfaces/jmoldata.py

@@ -21,7 +21,7 @@
 
 from sage.structure.sage_object import SageObject
 
-from sage.env import JMOL_DIR
+from sage.features.jmol import JmolDataJar
 from sage.misc.temporary_file import tmp_filename
 from sage.cpython.string import bytes_to_str
 
@@ -79,11 +79,11 @@ def jmolpath(self):
 
             sage: from sage.interfaces.jmoldata import JmolData
             sage: JData = JmolData()
-            sage: JData.jmolpath()
+            sage: JData.jmolpath()  # needs jmol
             '.../JmolData.jar'
 
         """
-        jmolpath = os.path.join(JMOL_DIR, "JmolData.jar")
+        jmolpath = JmolDataJar().absolute_filename()
 
         return jmolpath
 
@@ -100,7 +100,7 @@ def is_jmol_available(self):
             sage: type(JData.is_jmol_available())
             <... 'bool'>
         """
-        if not os.path.isfile(self.jmolpath()):
+        if not JmolDataJar().is_present():
             return False
 
         if not self.is_jvm_available():