Implements defclass

This fixes issue #156

Signed-off-by: Julien Danjou <julien@danjou.info>

hy/compiler.py

@@ -1301,9 +1301,13 @@ class HyASTCompiler(object):
     @builds("setv")
     @checkargs(2)
     def compile_def_expression(self, expression):
-        expression.pop(0)
-        name = expression.pop(0)
-        result = self.compile(expression.pop(0))
+        return self._compile_assign(expression[1], expression[2],
+                                    expression.start_line,
+                                    expression.start_column)
+
+    def _compile_assign(self, name, result,
+                        start_line, start_column):
+        result = self.compile(result)
 
         if result.temp_variables and isinstance(name, HyString):
             result.rename(name)
@@ -1313,8 +1317,8 @@ class HyASTCompiler(object):
         st_name = self._storeize(ld_name)
 
         result += ast.Assign(
-            lineno=expression.start_line,
-            col_offset=expression.start_column,
+            lineno=start_line,
+            col_offset=start_column,
             targets=[st_name], value=result.force_expr)
 
         result += ld_name
@@ -1440,6 +1444,56 @@ class HyASTCompiler(object):
 
         return ret
 
+    @builds("defclass")
+    @checkargs(min=1)
+    def compile_class_expression(self, expression):
+        expression.pop(0)  # class
+
+        class_name = expression.pop(0)
+
+        if expression:
+            base_list = expression.pop(0)
+            if not isinstance(base_list, HyList):
+                raise HyTypeError(expression,
+                                  "Bases class must be a list")
+            bases_expr, bases = self._compile_collect(base_list)
+        else:
+            bases_expr = []
+            bases = Result()
+
+        body = Result()
+
+        if expression:
+            try:
+                body_expression = iter(expression.pop(0))
+            except TypeError:
+                raise HyTypeError(
+                    expression,
+                    "Wrong argument type for defclass slots definition.")
+            for b in body_expression:
+                if len(b) != 2:
+                    raise HyTypeError(
+                        expression,
+                        "Wrong number of argument in defclass slot.")
+                body += self._compile_assign(b[0], b[1],
+                                             b.start_line, b.start_column)
+                body += body.expr_as_stmt()
+
+        if not body.stmts:
+            body += ast.Pass(lineno=expression.start_line,
+                             col_offset=expression.start_column)
+
+        return bases + ast.ClassDef(
+            lineno=expression.start_line,
+            col_offset=expression.start_column,
+            decorator_list=[],
+            name=ast_str(class_name),
+            keywords=[],
+            starargs=None,
+            kwargs=None,
+            bases=bases_expr,
+            body=body.stmts)
+
     @builds(HyInteger)
     def compile_integer(self, number):
         return ast.Num(n=int(number),

tests/__init__.py

@@ -2,6 +2,7 @@
 
 
 import hy  # noqa
+from .native_tests.defclass import *  # noqa
 from .native_tests.math import *  # noqa
 from .native_tests.language import *  # noqa
 from .native_tests.unless import *  # noqa

tests/compilers/test_ast.py

@@ -197,6 +197,19 @@ def test_ast_bad_global():
     cant_compile("(global foo bar)")
 
 
+def test_ast_good_defclass():
+    "Make sure AST can compile valid defclass"
+    hy_compile(tokenize("(defclass a)"))
+    hy_compile(tokenize("(defclass a [])"))
+
+
+def test_ast_bad_defclass():
+    "Make sure AST can't compile invalid defclass"
+    cant_compile("(defclass)")
+    cant_compile("(defclass a null)")
+    cant_compile("(defclass a null null)")
+
+
 def test_ast_good_lambda():
     "Make sure AST can compile valid lambda"
     hy_compile(tokenize("(lambda [])"))

tests/native_tests/defclass.hy

@@ -0,0 +1,62 @@
+(defn test-defclass []
+  "NATIVE: test defclass simple mechanism"
+  (defclass A)
+  (assert (isinstance (A) A)))
+
+
+(defn test-defclass-inheritance []
+  "NATIVE: test defclass inheritance"
+  (defclass A [])
+  (assert (isinstance (A) object))
+  (defclass A [object])
+  (assert (isinstance (A) object))
+  (defclass B [A])
+  (assert (isinstance (B) A))
+  (defclass C [object])
+  (defclass D [B C])
+  (assert (isinstance (D) A))
+  (assert (isinstance (D) B))
+  (assert (isinstance (D) C))
+  (assert (not (isinstance (A) D))))
+
+
+(defn test-defclass-slots []
+  "NATIVE: test defclass slots"
+  (defclass A []
+    [[x 42]])
+  (assert (= A.x 42))
+  (assert (= (getattr (A) "x")  42)))
+
+
+(defn test-defclass-slots-fn []
+  "NATIVE: test defclass slots with fn"
+  (defclass B []
+    [[x 42]
+     [y (fn [self value]
+          (+ self.x value))]])
+  (assert (= B.x 42))
+  (assert (= (.y (B) 5) 47))
+  (let [[b (B)]]
+    (setv B.x 0)
+    (assert (= (.y b 1) 1))))
+
+
+(defn test-defclass-dynamic-inheritance []
+  "NATIVE: test defclass with dynamic inheritance"
+  (defclass A [((fn [] (if true list dict)))]
+    [[x 42]])
+  (assert (isinstance (A) list))
+  (defclass A [((fn [] (if false list dict)))]
+    [[x 42]])
+  (assert (isinstance (A) dict)))
+
+
+(defn test-defclass-no-fn-leak []
+  "NATIVE: test defclass slots with fn"
+  (defclass A []
+    [[x (fn [] 1)]])
+  (try
+   (do
+    (x)
+    (assert false))
+   (except [NameError])))