MAINT: Require select for NEP 50 support

seberg · seberg · commit 61245d0a75d9 · 2023-07-12T12:26:18.000+02:00
This isn't quite ideally, it would be nice to grow specific code
for it (and actually, we currently allow some subclasses in other
paths, but I am planning to undo that).
diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
@@ -817,22 +817,19 @@ def select(condlist, choicelist, default=0):
     if len(condlist) == 0:
         raise ValueError("select with an empty condition list is not possible")
 
-    choicelist = [np.asarray(choice) for choice in choicelist]
+    # TODO: This preserves the Python int, float, complex manually to get the
+    #       right `result_type` with NEP 50.  Most likely we will grow a better
+    #       way to spell this (and this can be replaced).
+    choicelist = [
+        choice if type(choice) in (int, float, complex) else np.asarray(choice)
+        for choice in choicelist]
+    choicelist.append(default if type(default) in (int, float, complex)
+                      else np.asarray(default))
 
     try:
-        intermediate_dtype = np.result_type(*choicelist)
+        dtype = np.result_type(*choicelist)
     except TypeError as e:
-        msg = f'Choicelist elements do not have a common dtype: {e}'
-        raise TypeError(msg) from None
-    default_array = np.asarray(default)
-    choicelist.append(default_array)
-
-    # need to get the result type before broadcasting for correct scalar
-    # behaviour
-    try:
-        dtype = np.result_type(intermediate_dtype, default_array)
-    except TypeError as e:
-        msg = f'Choicelists and default value do not have a common dtype: {e}'
+        msg = f'Choicelist and default value do not have a common dtype: {e}'
         raise TypeError(msg) from None
 
     # Convert conditions to arrays and broadcast conditions and choices
