Add method to list and tuple class.

Author: windelbouwman

README.md

@@ -42,8 +42,11 @@ Documentation HTML files can then be found in the `target/doc` directory.
 
 # Code organization
 
-- `parser`: python lexing, parsing and ast
-- `vm`: python virtual machine
+- `parser/src`: python lexing, parsing and ast
+- `vm/src`: python virtual machine
+    - `builtins.rs`: Builtin functions
+    - `compile.rs`: the python compiler from ast to bytecode
+    - `obj`: python builtin types
 - `src`: using the other subcrates to bring rustpython to life.
 - `docs`: documentation (work in progress)
 - `py_code_object`: CPython bytecode to rustpython bytecode convertor (work in progress)
@@ -53,12 +56,15 @@ Documentation HTML files can then be found in the `target/doc` directory.
 # Contributing
 
 To start contributing, there are a lot of things that need to be done.
+
 Most tasks are listed in the [issue tracker](https://github.com/RustPython/RustPython/issues).
+Check issues labeled with `good first issue` if you wish to start coding.
+
 Another approach is to checkout the sourcecode: builtin functions and object methods are often the simplest
 and easiest way to contribute. 
 
 You can also simply run
-`cargo run tests/snippets/todo.py` to assist in finding any
+`cargo run tests/snippets/whats_left_to_implement.py` to assist in finding any
 unimplemented method.
 
 # Testing

vm/src/obj/objlist.rs

@@ -125,6 +125,23 @@ fn list_clear(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.get_none())
 }
 
+fn list_count(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(
+        vm,
+        args,
+        required = [(zelf, Some(vm.ctx.list_type())), (value, None)]
+    );
+    let elements = get_elements(zelf);
+    let mut count: usize = 0;
+    for element in elements.iter() {
+        let is_eq = vm._eq(element, value.clone())?;
+        if objbool::boolval(vm, is_eq)? {
+            count = count + 1;
+        }
+    }
+    Ok(vm.context().new_int(count.to_bigint().unwrap()))
+}
+
 pub fn list_extend(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
         vm,
@@ -152,6 +169,14 @@ fn list_reverse(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.get_none())
 }
 
+fn list_sort(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(list, Some(vm.ctx.list_type()))]);
+    let mut _elements = get_mut_elements(list);
+    unimplemented!("TODO: figure out how to invoke `sort_by` on a Vec");
+    // elements.sort_by();
+    // Ok(vm.get_none())
+}
+
 fn list_contains(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     trace!("list.contains called with: {:?}", args);
     arg_check!(
@@ -221,6 +246,8 @@ pub fn init(context: &PyContext) {
     list_type.set_attr("__repr__", context.new_rustfunc(list_repr));
     list_type.set_attr("append", context.new_rustfunc(list_append));
     list_type.set_attr("clear", context.new_rustfunc(list_clear));
+    list_type.set_attr("count", context.new_rustfunc(list_count));
     list_type.set_attr("extend", context.new_rustfunc(list_extend));
     list_type.set_attr("reverse", context.new_rustfunc(list_reverse));
+    list_type.set_attr("sort", context.new_rustfunc(list_sort));
 }

vm/src/obj/objtuple.rs

@@ -11,6 +11,23 @@ use super::objtype;
 use num_bigint::ToBigInt;
 use std::hash::{Hash, Hasher};
 
+fn tuple_count(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(
+        vm,
+        args,
+        required = [(zelf, Some(vm.ctx.tuple_type())), (value, None)]
+    );
+    let elements = get_elements(zelf);
+    let mut count: usize = 0;
+    for element in elements.iter() {
+        let is_eq = vm._eq(element, value.clone())?;
+        if objbool::boolval(vm, is_eq)? {
+            count = count + 1;
+        }
+    }
+    Ok(vm.context().new_int(count.to_bigint().unwrap()))
+}
+
 fn tuple_eq(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
         vm,
@@ -142,4 +159,5 @@ pub fn init(context: &PyContext) {
     tuple_type.set_attr("__len__", context.new_rustfunc(tuple_len));
     tuple_type.set_attr("__new__", context.new_rustfunc(tuple_new));
     tuple_type.set_attr("__repr__", context.new_rustfunc(tuple_repr));
+    tuple_type.set_attr("count", context.new_rustfunc(tuple_count));
 }

vm/src/pyobject.rs

@@ -642,6 +642,7 @@ impl AttributeProtocol for PyObjectRef {
 
     fn set_attr(&self, attr_name: &str, value: PyObjectRef) {
         match self.borrow().kind {
+            PyObjectKind::Module { name: _, ref dict } => dict.set_item(attr_name, value),
             PyObjectKind::Instance { ref dict } => dict.set_item(attr_name, value),
             PyObjectKind::Class {
                 name: _,