Class fields and access to class member methods

README.md

@@ -326,6 +326,22 @@ o.printFoo()
 
 _**Note:** As `self` is implicit, it can not be renamed; other argument names listed in a method signature will refer to additional arguments._
 
+Classes can also define fields, which can be accessed from the class or through an instance.
+
+```py
+class Foo():
+    bar = "baz"
+    def printBar(self):
+        print(self.bar)
+let o = Foo()
+o.printBar()
+# → baz
+print(Foo.bar)
+# → baz
+```
+
+_**Note:** Instances receive a copy of their class's fields upon creation. If a class field is mutable, the instance's copy will refer to the same underlying object. Assignments to the instance's copy of a field will refer to a new object. If a new field is added to a class after instances have been created, the existing instances will not be able to reference the new field._
+
 When a class is instantiated, if it has an `__init__` method it will be called automatically. `__init__` may take arguments as well.
 
 ```py

compiler.c

@@ -862,6 +862,16 @@ static void method(size_t blockWidth) {
 	 * as a redundant thing, just to make more Python stuff work with changes. */
 	if (check(TOKEN_AT)) {
 		decorator(0, TYPE_METHOD);
+	} else if (match(TOKEN_IDENTIFIER)) {
+		emitBytes(OP_DUP, 0); /* SET_PROPERTY will pop class */
+		size_t ind = identifierConstant(&parser.previous);
+		consume(TOKEN_EQUAL, "Class field must have value.");
+		expression();
+		EMIT_CONSTANT_OP(OP_SET_PROPERTY, ind);
+		emitByte(OP_POP); /* Value of expression replaces dup of class*/
+		if (!match(TOKEN_EOL) && !match(TOKEN_EOF)) {
+			errorAtCurrent("Expected end of line after class attribut declaration");
+		}
 	} else {
 		consume(TOKEN_DEF, "expected a definition, got nothing");
 		consume(TOKEN_IDENTIFIER, "expected method name");

object.c

@@ -114,6 +114,7 @@ KrkClass * krk_newClass(KrkString * name) {
 	_class->docstring = NULL;
 	_class->base = NULL;
 	krk_initTable(&_class->methods);
+	krk_initTable(&_class->fields);
 
 	_class->_getter = NULL;
 	_class->_setter = NULL;
@@ -131,6 +132,7 @@ KrkInstance * krk_newInstance(KrkClass * _class) {
 	KrkInstance * instance = ALLOCATE_OBJECT(KrkInstance, OBJ_INSTANCE);
 	instance->_class = _class;
 	krk_initTable(&instance->fields);
+	krk_tableAddAll(&_class->fields, &instance->fields);
 	instance->_internal = NULL; /* To be used by C-defined types to track internal objects. */
 	return instance;
 }

object.h

@@ -100,6 +100,7 @@ typedef struct KrkClass {
 	KrkString * docstring;
 	struct KrkClass * base;
 	KrkTable methods;
+	KrkTable fields;
 
 	/* Quick access for common stuff */
 	KrkObj * _getter;

src/fileio.c

@@ -288,6 +288,7 @@ KrkValue krk_module_onload_fileio(void) {
 	krk_attachNamedObject(&module->fields,chr_File,(KrkObj*)FileClass);
 	/* Inherit from object */
 	krk_tableAddAll(&vm.objectClass->methods, &FileClass->methods);
+	krk_tableAddAll(&vm.objectClass->fields, &FileClass->fields);
 	krk_pop();
 	krk_pop();
 

src/os.c

@@ -56,6 +56,7 @@ static void _loadEnviron(KrkInstance * module) {
 	KrkValue dictClass;
 	krk_tableGet(&vm.builtins->fields,OBJECT_VAL(S("dict")), &dictClass);
 	krk_tableAddAll(&AS_CLASS(dictClass)->methods, &environClass->methods);
+	krk_tableAddAll(&AS_CLASS(dictClass)->fields, &environClass->fields);
 	environClass->base = AS_CLASS(dictClass);
 
 	/* Add our set method that should also call dict's set method */

test/testClassFields.krk

@@ -0,0 +1,27 @@
+class Foo():
+    a = None
+    b = 42
+    c = "string"
+    l = []
+    def test(self):
+        return (self.a,self.b,self.c,self.l)
+
+class Bar(Foo):
+    c = 96
+
+let f = Foo()
+let b = Foo()
+def testAll():
+    print(Foo.test(Foo), f.test(), b.test(), Bar.test(Bar))
+
+testAll()
+f.a = 42
+testAll()
+f.l.append("hi")
+testAll()
+f.l = []
+testAll()
+f.l.append("bacon")
+testAll()
+b.b = "derp"
+testAll()

test/testClassFields.krk.expect

@@ -0,0 +1,6 @@
+(None, 42, 'string', []) (None, 42, 'string', []) (None, 42, 'string', []) (None, 42, 96, [])
+(None, 42, 'string', []) (42, 42, 'string', []) (None, 42, 'string', []) (None, 42, 96, [])
+(None, 42, 'string', ['hi']) (42, 42, 'string', ['hi']) (None, 42, 'string', ['hi']) (None, 42, 96, ['hi'])
+(None, 42, 'string', ['hi']) (42, 42, 'string', []) (None, 42, 'string', ['hi']) (None, 42, 96, ['hi'])
+(None, 42, 'string', ['hi']) (42, 42, 'string', ['bacon']) (None, 42, 'string', ['hi']) (None, 42, 96, ['hi'])
+(None, 42, 'string', ['hi']) (42, 42, 'string', ['bacon']) (None, 'derp', 'string', ['hi']) (None, 42, 96, ['hi'])

test/testClassMethod.krk

@@ -0,0 +1,23 @@
+def staticmethod(func):
+    def _wrapper(*args,**kwargs):
+        return func(None,*args,**kwargs)
+    return _wrapper
+
+class Foo():
+    def amethod():
+        print("If this were Python, I'd be impossible to call.")
+    @staticmethod
+    def astatic():
+        print("Since `None` is always implicit, it's been set by @staticmethod here to None:", self)
+
+# This doesn't work because amethod is unbound and needs an instance.
+try:
+    Foo.amethod()
+except:
+    print(exception.arg)
+# This works
+Foo.amethod(Foo())
+# This should too?
+Foo.astatic()
+
+

test/testClassMethod.krk.expect

@@ -0,0 +1,3 @@
+amethod() takes exactly 1 argument (0 given)
+If this were Python, I'd be impossible to call.
+Since `None` is always implicit, it's been set by @staticmethod here to None: None

vm.c

@@ -733,6 +733,21 @@ KrkValue krk_dirObject(int argc, KrkValue argv[]) {
 			}
 		}
 	} else {
+		if (IS_CLASS(argv[0])) {
+			KrkClass * _class = AS_CLASS(argv[0]);
+			for (size_t i = 0; i < _class->methods.capacity; ++i) {
+				if (_class->methods.entries[i].key.type != VAL_KWARGS) {
+					krk_writeValueArray(AS_LIST(_list_internal),
+						_class->methods.entries[i].key);
+				}
+			}
+			for (size_t i = 0; i < _class->fields.capacity; ++i) {
+				if (_class->fields.entries[i].key.type != VAL_KWARGS) {
+					krk_writeValueArray(AS_LIST(_list_internal),
+						_class->fields.entries[i].key);
+				}
+			}
+		}
 		KrkClass * type = AS_CLASS(krk_typeOf(1, (KrkValue[]){argv[0]}));
 
 		for (size_t i = 0; i < type->methods.capacity; ++i) {
@@ -1368,6 +1383,7 @@ static KrkValue _string_init(int argc, KrkValue argv[]) {
 	krk_attachNamedObject(&vm.builtins->fields, name, (KrkObj*)obj); \
 	obj->base = baseClass; \
 	krk_tableAddAll(&baseClass->methods, &obj->methods); \
+	krk_tableAddAll(&baseClass->fields, &obj->fields); \
 } while (0)
 
 #define ADD_EXCEPTION_CLASS(obj, name, baseClass) do { \
@@ -1375,6 +1391,7 @@ static KrkValue _string_init(int argc, KrkValue argv[]) {
 	krk_attachNamedObject(&vm.builtins->fields, name, (KrkObj*)obj); \
 	obj->base = baseClass; \
 	krk_tableAddAll(&baseClass->methods, &obj->methods); \
+	krk_tableAddAll(&baseClass->fields, &obj->fields); \
 } while (0)
 
 #define BUILTIN_FUNCTION(name, func) do { \
@@ -2680,6 +2697,7 @@ void krk_initVM(int flags) {
 	vm.moduleClass = krk_newClass(S("module"));
 	vm.moduleClass->base = vm.objectClass;
 	krk_tableAddAll(&vm.objectClass->methods, &vm.moduleClass->methods);
+	krk_tableAddAll(&vm.objectClass->fields, &vm.moduleClass->fields);
 
 	/* Attach new repr/str */
 	krk_defineNative(&vm.moduleClass->methods, ".__repr__", _module_repr);
@@ -3240,15 +3258,24 @@ int krk_loadModule(KrkString * name, KrkValue * moduleOut) {
  */
 static int valueGetProperty(KrkString * name) {
 	KrkClass * objectClass;
+	KrkValue value;
 	if (IS_INSTANCE(krk_peek(0))) {
 		KrkInstance * instance = AS_INSTANCE(krk_peek(0));
-		KrkValue value;
 		if (krk_tableGet(&instance->fields, OBJECT_VAL(name), &value)) {
 			krk_pop();
 			krk_push(value);
 			return 1;
 		}
 		objectClass = instance->_class;
+	} else if (IS_CLASS(krk_peek(0))) {
+		KrkClass * _class = AS_CLASS(krk_peek(0));
+		if (krk_tableGet(&_class->fields, OBJECT_VAL(name), &value) ||
+			krk_tableGet(&_class->methods, OBJECT_VAL(name), &value)) {
+			krk_pop();
+			krk_push(value);
+			return 1;
+		}
+		objectClass = AS_CLASS(krk_typeOf(1, (KrkValue[]){krk_peek(0)}));
 	} else {
 		objectClass = AS_CLASS(krk_typeOf(1, (KrkValue[]){krk_peek(0)}));
 	}
@@ -3570,6 +3597,7 @@ static KrkValue run() {
 				_class->filename = frame->closure->function->chunk.filename;
 				_class->base = vm.objectClass;
 				krk_tableAddAll(&vm.objectClass->methods, &_class->methods);
+				krk_tableAddAll(&vm.objectClass->fields, &_class->fields);
 				break;
 			}
 			case OP_GET_PROPERTY_LONG:
@@ -3615,15 +3643,18 @@ static KrkValue run() {
 			case OP_SET_PROPERTY_LONG:
 			case OP_SET_PROPERTY: {
 				KrkString * name = READ_STRING(operandWidth);
-				if (!IS_INSTANCE(krk_peek(1))) {
+				if (IS_INSTANCE(krk_peek(1))) {
+					KrkInstance * instance = AS_INSTANCE(krk_peek(1));
+					krk_tableSet(&instance->fields, OBJECT_VAL(name), krk_peek(0));
+				} else if (IS_CLASS(krk_peek(1))) {
+					KrkClass * _class = AS_CLASS(krk_peek(1));
+					krk_tableSet(&_class->fields, OBJECT_VAL(name), krk_peek(0));
+				} else {
 					krk_runtimeError(vm.exceptions.attributeError, "'%s' object has no attribute '%s'", krk_typeName(krk_peek(0)), name->chars);
 					goto _finishException;
 				}
-				KrkInstance * instance = AS_INSTANCE(krk_peek(1));
-				krk_tableSet(&instance->fields, OBJECT_VAL(name), krk_peek(0));
-				KrkValue value = krk_pop();
-				krk_pop(); /* instance */
-				krk_push(value); /* Moves value in */
+				krk_swap(1);
+				krk_pop();
 				break;
 			}
 			case OP_METHOD_LONG:
@@ -3651,6 +3682,7 @@ static KrkValue run() {
 				KrkClass * subclass = AS_CLASS(krk_peek(0));
 				subclass->base = AS_CLASS(superclass);
 				krk_tableAddAll(&AS_CLASS(superclass)->methods, &subclass->methods);
+				krk_tableAddAll(&AS_CLASS(superclass)->fields, &subclass->fields);
 				krk_pop();
 				break;
 			}