Changes suggested in PR review

mathics/builtin/assignments/assignment.py

@@ -4,8 +4,27 @@
 """
 
 
-from mathics.builtin.assignments.internals import _SetOperator
 from mathics.builtin.base import BinaryOperator, Builtin
+from mathics.core.assignment import (
+    AssignmentException,
+    assign_store_rules_by_tag,
+    normalize_lhs,
+    process_assign_attributes,
+    process_assign_context,
+    process_assign_context_path,
+    process_assign_default,
+    process_assign_definition_values,
+    process_assign_format,
+    process_assign_list,
+    process_assign_makeboxes,
+    process_assign_messagename,
+    process_assign_n,
+    process_assign_numericq,
+    process_assign_options,
+    process_assign_random_state,
+    process_assign_part,
+)
+
 from mathics.core.attributes import (
     A_HOLD_ALL,
     A_HOLD_FIRST,
@@ -18,6 +37,62 @@
 from mathics.core.systemsymbols import SymbolFailed
 
 
+class _SetOperator:
+    """
+    This is the base class for assignment Builtin operators.
+
+    Special cases are determined by the head of the expression. Then
+    they are processed by specific routines, which are poke from
+    the `special_cases` dict.
+    """
+
+    # FIXME:
+    # Assigment is determined by the LHS.
+    # Is there a larger patterns or natural grouping that we are missing?
+    # For example it might be that
+    # there are some attributes or other properties of of the
+    # LHS of a builtin that we should be targetting.
+    # Below, we key on a string, but Symbol is more correct.
+    #
+
+    special_cases = {
+        "System`$Context": process_assign_context,
+        "System`$ContextPath": process_assign_context_path,
+        "System`$RandomState": process_assign_random_state,
+        "System`Attributes": process_assign_attributes,
+        "System`Default": process_assign_default,
+        "System`DefaultValues": process_assign_definition_values,
+        "System`DownValues": process_assign_definition_values,
+        "System`Format": process_assign_format,
+        "System`List": process_assign_list,
+        "System`MakeBoxes": process_assign_makeboxes,
+        "System`MessageName": process_assign_messagename,
+        "System`Messages": process_assign_definition_values,
+        "System`N": process_assign_n,
+        "System`NValues": process_assign_definition_values,
+        "System`NumericQ": process_assign_numericq,
+        "System`Options": process_assign_options,
+        "System`OwnValues": process_assign_definition_values,
+        "System`Part": process_assign_part,
+        "System`SubValues": process_assign_definition_values,
+        "System`UpValues": process_assign_definition_values,
+    }
+
+    def assign(self, lhs, rhs, evaluation, tags=None, upset=False):
+        lhs, lookup_name = normalize_lhs(lhs, evaluation)
+        try:
+            # Deal with direct assignation to properties of
+            # the definition object
+            func = self.special_cases.get(lookup_name, None)
+            if func:
+                return func(self, lhs, rhs, evaluation, tags, upset)
+
+            return assign_store_rules_by_tag(self, lhs, rhs, evaluation, tags, upset)
+        except AssignmentException:
+
+            return False
+
+
 class Set(BinaryOperator, _SetOperator):
     """
     <dl>

mathics/builtin/assignments/clear.py

@@ -38,10 +38,9 @@
     SymbolUpValues,
 )
 
+from mathics.core.assignment import is_protected
 from mathics.core.atoms import String
 
-from mathics.builtin.assignments.internals import is_protected
-
 
 class Clear(Builtin):
     """

mathics/builtin/assignments/types.py

@@ -8,8 +8,7 @@
 
 from mathics.builtin.base import Builtin
 
-from mathics.builtin.assignments.internals import get_symbol_values
-
+from mathics.core.assignment import get_symbol_values
 from mathics.core.attributes import A_HOLD_ALL, A_PROTECTED
 
 

mathics/builtin/assignments/upvalues.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 
 
-from mathics.builtin.assignments.internals import _SetOperator
+from mathics.builtin.assignments.assignment import _SetOperator
 from mathics.builtin.base import BinaryOperator
 from mathics.core.attributes import (
     A_HOLD_ALL,

mathics/builtin/atomic/symbols.py

@@ -7,7 +7,6 @@
 
 import re
 
-from mathics.builtin.assignments.internals import get_symbol_values
 from mathics.builtin.base import (
     Builtin,
     PrefixOperator,
@@ -16,6 +15,7 @@
 
 from mathics.builtin.atomic.strings import to_regex
 
+from mathics.core.assignment import get_symbol_values
 from mathics.core.atoms import String
 
 from mathics.core.attributes import (

mathics/builtin/attributes.py

@@ -15,7 +15,7 @@
 
 
 from mathics.builtin.base import Predefined, Builtin
-from mathics.builtin.assignments.internals import get_symbol_list
+from mathics.core.assignment import get_symbol_list
 from mathics.core.atoms import String
 from mathics.core.attributes import (
     attributes_bitset_to_list,

mathics/builtin/scoping.py

@@ -4,13 +4,13 @@
 """
 
 
-from mathics.builtin.assignments.internals import get_symbol_list
 from mathics.core.attributes import (
     A_HOLD_ALL,
     A_PROTECTED,
     attribute_string_to_number,
 )
 from mathics.builtin.base import Builtin, Predefined
+from mathics.core.assignment import get_symbol_list
 from mathics.core.atoms import (
     String,
     Integer,