feat: trigger rebind on set attribute

bolt/codegen.py

@@ -155,9 +155,10 @@ def children(self, nodes: Iterable[str]) -> str:
         """Emit children helper."""
         return self.helper("children", f"[{', '.join(nodes)}]")
 
-    def get_attribute(self, obj: str, name: str) -> str:
-        """Emit get_attribute helper."""
-        return self.helper("get_attribute", obj, repr(name))
+    def get_attribute_handler(self, obj: str, name: str) -> str:
+        """Emit get_attribute_handler helper."""
+        attribute_handler = self.helper("get_attribute_handler", obj)
+        return f'{attribute_handler}["{name}"]'
 
     def import_module(self, name: str) -> str:
         """Emit import_module helper."""
@@ -1025,7 +1026,7 @@ def from_import_statement(
             stmt = f"_bolt_from_import = {acc.import_module(module.path)}"
             acc.statement(stmt, lineno=node)
             for name in names:
-                rhs = acc.get_attribute("_bolt_from_import", name)
+                rhs = acc.get_attribute_handler("_bolt_from_import", name)
                 acc.statement(f"{name} = {rhs}", lineno=node)
 
         return []
@@ -1303,7 +1304,7 @@ def attribute(
         acc: Accumulator,
     ) -> Generator[AstNode, Optional[List[str]], Optional[List[str]]]:
         value = yield from visit_single(node.value, required=True)
-        rhs = acc.get_attribute(value, node.name)
+        rhs = acc.get_attribute_handler(value, node.name)
         acc.statement(f"{value} = {rhs}", lineno=node)
         return [value]
 
@@ -1389,7 +1390,8 @@ def target_attribute(
         acc: Accumulator,
     ) -> Generator[AstNode, Optional[List[str]], Optional[List[str]]]:
         value = yield from visit_single(node.value, required=True)
-        return [f"{value}.{node.name}"]
+        target = acc.get_attribute_handler(value, node.name)
+        return [target]
 
     @rule(AstTargetItem)
     def target_item(

bolt/contrib/sandbox.py

@@ -3,7 +3,7 @@
 
 __all__ = [
     "Sandbox",
-    "SandboxedGetAttribute",
+    "SandboxedAttributeHandler",
     "SandboxedImportModule",
     "SecurityError",
     "public_attrs",
@@ -184,11 +184,16 @@ def activate(self):
         if self.active:
             return
         self.active = True
+
         self.runtime.builtins &= self.allowed_builtins
+
+        get_attribute_handler = self.runtime.helpers["get_attribute_handler"]
+
         self.runtime.helpers.update(
-            get_attribute=SandboxedGetAttribute(
+            get_attribute_handler=lambda obj: SandboxedAttributeHandler(  # type: ignore
+                obj=obj,
+                handler=get_attribute_handler(obj),
                 sandbox=self,
-                get_attribute=self.runtime.helpers["get_attribute"],
             ),
             import_module=SandboxedImportModule(
                 sandbox=self,
@@ -198,30 +203,31 @@ def activate(self):
 
 
 @dataclass
-class SandboxedGetAttribute:
-    """Sandboxed get_attribute helper."""
+class SandboxedAttributeHandler:
+    """Sandboxed attribute handler helper."""
 
+    obj: Any
+    handler: Any
     sandbox: Sandbox
-    get_attribute: Callable[[Any, str], Any]
 
     @internal
-    def __call__(self, obj: Any, attr: str) -> Any:
-        if not hasattr(obj, attr):
-            return self.get_attribute(obj, attr)
+    def __getitem__(self, attr: str) -> Any:
+        if not hasattr(self.obj, attr):
+            return self.handler[attr]
 
         try:
-            if allowed := self.sandbox.allowed_obj_attrs.get(obj):
+            if allowed := self.sandbox.allowed_obj_attrs.get(self.obj):
                 if attr in allowed:
-                    return self.get_attribute(obj, attr)
+                    return self.handler[attr]
         except TypeError:
             pass
 
-        for cls in type.mro(type(obj)):
+        for cls in type.mro(type(self.obj)):
             if allowed := self.sandbox.allowed_type_attrs.get(cls):
                 if attr in allowed:
-                    return self.get_attribute(obj, attr)
+                    return self.handler[attr]
 
-        raise SecurityError(f"Access forbidden attribute {attr!r} of {type(obj)}.")
+        raise SecurityError(f"Access forbidden attribute {attr!r} of {type(self.obj)}.")
 
 
 @dataclass

bolt/helpers.py

@@ -62,7 +62,7 @@ def get_bolt_helpers() -> Dict[str, Any]:
         "branch": BranchDriver,
         "get_dup": get_dup,
         "get_rebind": get_rebind,
-        "get_attribute": get_attribute,
+        "get_attribute_handler": AttributeHandler,
         "import_module": python_import_module,
         "macro_call": macro_call,
         "resolve_formatted_location": resolve_formatted_location,
@@ -166,15 +166,47 @@ def get_rebind(obj: Any):
     return None
 
 
-@internal
-def get_attribute(obj: Any, attr: str):
-    try:
-        return getattr(obj, attr)
-    except AttributeError as exc:
+@dataclass
+class AttributeHandler:
+    obj: Any
+    item: bool = False
+
+    @internal
+    def __getitem__(self, attr: str) -> Any:
+        try:
+            return getattr(self.obj, attr)
+        except AttributeError as exc:
+            try:
+                result = self.obj[attr]
+                self.item = True
+                return result
+            except (TypeError, LookupError):
+                raise exc from None
+
+    @internal
+    def __setitem__(self, attr: str, value: Any):
+        try:
+            current = self.__getitem__(attr)
+        except AttributeError:
+            pass
+        else:
+            if func := getattr(type(current), "__rebind__", None):
+                value = func(current, value)
+        if self.item:
+            self.obj[attr] = value
+        else:
+            setattr(self.obj, attr, value)
+
+    @internal
+    def __delitem__(self, attr: str):
         try:
-            return obj[attr]
-        except (TypeError, LookupError):
-            raise exc from None
+            self.__getitem__(attr)
+        except AttributeError:
+            pass
+        if self.item:
+            del self.obj[attr]
+        else:
+            delattr(self.obj, attr)
 
 
 @internal

examples/bolt_basic/src/data/demo/functions/attribute_rebind.mcfunction

@@ -0,0 +1,83 @@
+from dataclasses import dataclass
+
+@dataclass
+class Var:
+    name: str
+
+    def __add__(self, value):
+        result = Var(f"{self}_plus_{value}")
+        say f"{result} = {self} + {value}"
+        return result
+
+    def __rebind__(self, value):
+        say f"{self.name} = {value}"
+        return self
+
+    def __str__(self):
+        return self.name
+
+foo = Var("foo")
+bar = Var("bar")
+say f"{foo} {bar}"
+
+foo = 123
+foo += 456
+foo = bar + 789
+foo += bar + 999
+
+del foo
+del bar
+
+foo = 123
+bar = 456
+say f"{foo} {bar}"
+
+@dataclass
+class A:
+    foo: Var
+    bar: Var
+
+a = A(Var("foo"), Var("bar"))
+say a
+
+a.foo = 123
+a.foo += 456
+a.foo = a.bar + 789
+a.foo += a.bar + 999
+
+del a.foo
+del a.bar
+
+a.foo = 123
+a.bar = 456
+say a
+
+b = {ayy: Var("ayy"), yoo: Var("yoo")}
+say b
+
+b.ayy = 123
+b.ayy += 456
+b.ayy = b.yoo + 789
+b.ayy += b.yoo + 999
+
+del b.ayy
+del b.yoo
+
+b["ayy"] = 123
+b["yoo"] = 456
+say b
+
+c = {ayy: Var("ayy"), yoo: Var("yoo")}
+say c
+
+c["ayy"] = 123
+c["ayy"] += 456
+c["ayy"] = c["yoo"] + 789
+c["ayy"] += c["yoo"] + 999
+
+del c.ayy
+del c.yoo
+
+c["ayy"] = 123
+c["yoo"] = 456
+say c

tests/snapshots/bolt__parse_126__1.txt

@@ -1,12 +1,12 @@
 _bolt_lineno = [1, 8], [1, 2]
 _bolt_helper_import_module = _bolt_runtime.helpers['import_module']
-_bolt_helper_get_attribute = _bolt_runtime.helpers['get_attribute']
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_replace = _bolt_runtime.helpers['replace']
 with _bolt_runtime.scope() as _bolt_var2:
     math = _bolt_helper_import_module('math')
     _bolt_var0 = math
-    _bolt_var0 = _bolt_helper_get_attribute(_bolt_var0, 'sin')
+    _bolt_var0 = _bolt_helper_get_attribute_handler(_bolt_var0)["sin"]
     _bolt_var1 = 1
     _bolt_var0 = _bolt_var0(_bolt_var1)
 _bolt_var3 = _bolt_helper_replace(_bolt_refs[0], commands=_bolt_helper_children(_bolt_var2))

tests/snapshots/bolt__parse_127__1.txt

@@ -1,12 +1,12 @@
 _bolt_lineno = [1, 8], [1, 2]
 _bolt_helper_import_module = _bolt_runtime.helpers['import_module']
-_bolt_helper_get_attribute = _bolt_runtime.helpers['get_attribute']
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_replace = _bolt_runtime.helpers['replace']
 with _bolt_runtime.scope() as _bolt_var2:
     m = _bolt_helper_import_module('math')
     _bolt_var0 = m
-    _bolt_var0 = _bolt_helper_get_attribute(_bolt_var0, 'sin')
+    _bolt_var0 = _bolt_helper_get_attribute_handler(_bolt_var0)["sin"]
     _bolt_var1 = 1
     _bolt_var0 = _bolt_var0(_bolt_var1)
 _bolt_var3 = _bolt_helper_replace(_bolt_refs[0], commands=_bolt_helper_children(_bolt_var2))

tests/snapshots/bolt__parse_139__1.txt

@@ -1,5 +1,5 @@
 _bolt_lineno = [1, 15, 20, 28, 40], [1, 2, 3, 4, 6]
-_bolt_helper_get_attribute = _bolt_runtime.helpers['get_attribute']
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_interpolate_resource_location = _bolt_runtime.helpers['interpolate_resource_location']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_operator_not = _bolt_runtime.helpers['operator_not']
@@ -13,37 +13,37 @@ with _bolt_runtime.scope() as _bolt_var10:
     _bolt_var0 = _bolt_var0(_bolt_var1)
     for node in _bolt_var0:
         _bolt_var2 = node
-        _bolt_var2 = _bolt_helper_get_attribute(_bolt_var2, 'parent')
+        _bolt_var2 = _bolt_helper_get_attribute_handler(_bolt_var2)["parent"]
         _bolt_var2 = _bolt_helper_interpolate_resource_location(_bolt_var2, _bolt_refs[0])
         with _bolt_runtime.push_nesting('append:function:name:commands', *_bolt_helper_children([_bolt_var2])):
             with _bolt_runtime.scope() as _bolt_var9:
                 _bolt_var3 = node
-                _bolt_var3 = _bolt_helper_get_attribute(_bolt_var3, 'partition')
+                _bolt_var3 = _bolt_helper_get_attribute_handler(_bolt_var3)["partition"]
                 _bolt_var4 = 5
                 _bolt_var3 = _bolt_var3(_bolt_var4)
                 _bolt_var3_inverse = _bolt_helper_operator_not(_bolt_var3)
                 with _bolt_helper_branch(_bolt_var3) as _bolt_condition:
                     if _bolt_condition:
                         with _bolt_runtime.push_nesting('execute:subcommand'):
                             _bolt_var5 = node
-                            _bolt_var5 = _bolt_helper_get_attribute(_bolt_var5, 'range')
+                            _bolt_var5 = _bolt_helper_get_attribute_handler(_bolt_var5)["range"]
                             _bolt_var5 = _bolt_helper_interpolate_range(_bolt_var5, _bolt_refs[1])
                             with _bolt_runtime.push_nesting('execute:if:score:target:targetObjective:matches:range:subcommand', *_bolt_helper_children([_bolt_refs[2], _bolt_refs[3], _bolt_var5])):
                                 with _bolt_runtime.push_nesting('execute:run:subcommand'):
                                     _bolt_var6 = node
-                                    _bolt_var6 = _bolt_helper_get_attribute(_bolt_var6, 'children')
+                                    _bolt_var6 = _bolt_helper_get_attribute_handler(_bolt_var6)["children"]
                                     _bolt_var6 = _bolt_helper_interpolate_resource_location(_bolt_var6, _bolt_refs[4])
                         _bolt_runtime.commands.append(_bolt_helper_replace(_bolt_refs[8], arguments=_bolt_helper_children([_bolt_helper_replace(_bolt_refs[7], arguments=_bolt_helper_children([*_bolt_helper_children([_bolt_refs[2], _bolt_refs[3], _bolt_var5]), _bolt_helper_replace(_bolt_refs[6], arguments=_bolt_helper_children([_bolt_helper_replace(_bolt_refs[5], arguments=_bolt_helper_children([_bolt_var6]))]))]))])))
                 with _bolt_helper_branch(_bolt_var3_inverse) as _bolt_condition:
                     if _bolt_condition:
                         with _bolt_runtime.push_nesting('execute:subcommand'):
                             _bolt_var7 = node
-                            _bolt_var7 = _bolt_helper_get_attribute(_bolt_var7, 'range')
+                            _bolt_var7 = _bolt_helper_get_attribute_handler(_bolt_var7)["range"]
                             _bolt_var7 = _bolt_helper_interpolate_range(_bolt_var7, _bolt_refs[9])
                             with _bolt_runtime.push_nesting('execute:if:score:target:targetObjective:matches:range:subcommand', *_bolt_helper_children([_bolt_refs[10], _bolt_refs[11], _bolt_var7])):
                                 with _bolt_runtime.push_nesting('execute:run:subcommand'):
                                     _bolt_var8 = node
-                                    _bolt_var8 = _bolt_helper_get_attribute(_bolt_var8, 'value')
+                                    _bolt_var8 = _bolt_helper_get_attribute_handler(_bolt_var8)["value"]
                                     _bolt_var8 = _bolt_helper_interpolate_message(_bolt_var8, _bolt_refs[12])
                         _bolt_runtime.commands.append(_bolt_helper_replace(_bolt_refs[16], arguments=_bolt_helper_children([_bolt_helper_replace(_bolt_refs[15], arguments=_bolt_helper_children([*_bolt_helper_children([_bolt_refs[10], _bolt_refs[11], _bolt_var7]), _bolt_helper_replace(_bolt_refs[14], arguments=_bolt_helper_children([_bolt_helper_replace(_bolt_refs[13], arguments=_bolt_helper_children([_bolt_var8]))]))]))])))
         _bolt_runtime.commands.append(_bolt_helper_replace(_bolt_refs[18], arguments=_bolt_helper_children([*_bolt_helper_children([_bolt_var2]), _bolt_helper_replace(_bolt_refs[17], commands=_bolt_helper_children(_bolt_var9))])))

tests/snapshots/bolt__parse_140__1.txt

@@ -1,11 +1,11 @@
 _bolt_lineno = [1], [1]
-_bolt_helper_get_attribute = _bolt_runtime.helpers['get_attribute']
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_replace = _bolt_runtime.helpers['replace']
 with _bolt_runtime.scope() as _bolt_var3:
     _bolt_var0 = print
     _bolt_var1 = ctx
-    _bolt_var1 = _bolt_helper_get_attribute(_bolt_var1, 'directory')
+    _bolt_var1 = _bolt_helper_get_attribute_handler(_bolt_var1)["directory"]
     _bolt_var2 = __name__
     _bolt_var0 = _bolt_var0(_bolt_var1, _bolt_var2)
 _bolt_var4 = _bolt_helper_replace(_bolt_refs[0], commands=_bolt_helper_children(_bolt_var3))

tests/snapshots/bolt__parse_160__1.txt

@@ -1,11 +1,12 @@
-_bolt_lineno = [1, 6], [1, 2]
+_bolt_lineno = [1, 7], [1, 2]
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_replace = _bolt_runtime.helpers['replace']
 with _bolt_runtime.scope() as _bolt_var0:
     def f():
         _bolt_var0 = {}
         _bolt_var1 = f
-        _bolt_var1.data = _bolt_var0
+        _bolt_helper_get_attribute_handler(_bolt_var1)["data"] = _bolt_var0
 _bolt_var1 = _bolt_helper_replace(_bolt_refs[0], commands=_bolt_helper_children(_bolt_var0))
 ---
 output = _bolt_var1

tests/snapshots/bolt__parse_162__1.txt

@@ -1,4 +1,5 @@
-_bolt_lineno = [1, 10], [1, 2]
+_bolt_lineno = [1, 11], [1, 2]
+_bolt_helper_get_attribute_handler = _bolt_runtime.helpers['get_attribute_handler']
 _bolt_helper_children = _bolt_runtime.helpers['children']
 _bolt_helper_replace = _bolt_runtime.helpers['replace']
 with _bolt_runtime.scope() as _bolt_var5:
@@ -8,7 +9,7 @@ with _bolt_runtime.scope() as _bolt_var5:
     d = _bolt_var2
     _bolt_var3 = 1
     _bolt_var4 = d
-    _bolt_var4.foo += _bolt_var3
+    _bolt_helper_get_attribute_handler(_bolt_var4)["foo"] += _bolt_var3
 _bolt_var6 = _bolt_helper_replace(_bolt_refs[0], commands=_bolt_helper_children(_bolt_var5))
 ---
 output = _bolt_var6