Implement len() and py.Len

Author: ncw

builtin/builtin.go

@@ -42,7 +42,7 @@ func init(){
 // py.NewMethod("isinstance", builtin_isinstance, 0, isinstance_doc),
 // py.NewMethod("issubclass", builtin_issubclass, 0, issubclass_doc),
 // py.NewMethod("iter", builtin_iter, 0, iter_doc),
-// py.NewMethod("len", builtin_len, 0, len_doc),
+py.NewMethod("len", builtin_len, 0, len_doc),
 // py.NewMethod("locals", builtin_locals, py.METH_NOARGS, locals_doc),
 // py.NewMethod("max", builtin_max, 0, max_doc),
 // py.NewMethod("min", builtin_min, 0, min_doc),
@@ -549,3 +549,11 @@ func builtin_compile(self py.Object, args py.Tuple, kwargs py.StringDict) py.Obj
 
 returnresult
 }
+
+constlen_doc=`len(object) -> integer
+
+Return the number of items of a sequence or mapping.`
+
+funcbuiltin_len(self, v py.Object) py.Object{
+returnpy.Len(v)
+}

notes.txt

@@ -31,6 +31,19 @@ When converting C code, run it through astyle first as a first pass
 
 astyle --style=java --add-brackets < x.c > x.go
 
+Roadmap
+=======
+ * FIXME catching an exception is stopping the error return / traceback working
+ * FIXME (int("a", base=16): gives int() got multiple values for argument 'base'
+ * make pystone.py work
+ * make enough of internals work so can run python tests
+ * import python tests and write go test runner to run them
+ * make lots of them pass
+
+Missing parts
+=============
+ * repr/str
+ * subclassing built in types
 
 Polymorphism
 ============

py/internal.go

@@ -75,6 +75,16 @@ func IndexIntCheck(a Object, max int) int{
 returni
 }
 
+// Returns the number of items of a sequence or mapping
+funcLen(selfObject) Object{
+ifI, ok:=self.(I__len__); ok{
+returnI.M__len__()
+ } elseifres, ok:=TypeCall0(self, "__len__"); ok{
+returnres
+ }
+panic(ExceptionNewf(TypeError, "object of type '%s' has no len()", self.Type().Name))
+}
+
 // Return the result of not a
 funcNot(aObject) Object{
 switchMakeBool(a){