trac 16522: introduce debugging routine to access LazyImport attribut…

…es and a routine to clean namespaces of misconfigured LazyImport objects

src/sage/misc/lazy_import.pyx

@@ -1163,6 +1163,65 @@ def get_star_imports(module_name):
         star_imports[module_name] = all
         return all
 
+def attributes(a):
+    """
+    Returns the private attributes of a LazyImport object in a dictionary (for debugging purposes).
+
+    EXAMPLES::
+
+        sage: from sage.misc.lazy_import import attributes
+        sage: lazy_import("sage.all","foo")
+        sage: attributes(foo)['_namespace'] is globals()
+        True
+        sage: D=attributes(foo)
+        sage: del D['_namespace']
+        sage: D
+        {'_as_name': 'foo',
+         '_at_startup': False,
+         '_deprecation': None,
+         '_module': 'sage.all',
+         '_name': 'foo',
+         '_object': None}
+    """
+    cdef LazyImport b
+    b = a
+    return {"_object": b._object,
+            "_module": b._module,
+            "_name": b._name,
+            "_as_name": b._as_name,
+            "_namespace": b._namespace,
+            "_at_startup": b._at_startup,
+            "_deprecation": b._deprecation}
+
+def clean_namespace(namespace):
+    """
+    Adjusts LazyImport bindings in given namespace to refer to this actual namespace.
+
+    When LazyImport objects are imported into other namespaces via normal import
+    instructions, then the data stored on a LazyImport object that helps it to adjust the
+    binding in the namespace to the actual imported object upon access, is not adjusted.
+    This routine fixes that.
+
+    EXAMPLES::
+
+        sage: from sage.misc.lazy_import import attributes, clean_namespace
+        sage: from sage.calculus.calculus import maxima as C
+        sage: attributes(C)['_as_name']
+        'maxima'
+        sage: attributes(C)['_namespace'] is sage.calculus.calculus.__dict__
+        True
+        sage: clean_namespace(globals())
+        sage: attributes(C)['_as_name']
+        'C'
+        sage: attributes(C)['_namespace'] is globals()
+        True
+    """
+    cdef LazyImport w
+    for k,v in namespace.items():
+        if type(v) is LazyImport:
+            w = v
+            if w._namespace is not None and (w._namespace is not namespace or w._as_name != k):
+                namespace[k]=LazyImport(w._module, w._name, as_name=k, at_startup=w._at_startup, namespace=namespace, deprecation=w._deprecation)
 
 # Add support for _instancedoc_
 from sage.misc.instancedoc import instancedoc