Merge pull request #332 from lausek/imports

raise ImportError in import list

tests/snippets/import.py

@@ -16,6 +16,12 @@ assert import_target.Y == aliased_other_func()
 
 assert STAR_IMPORT == '123'
 
+try:
+    from import_target import func, unknown_name
+    raise AssertionError('`unknown_name` does not cause an exception')
+except ImportError:
+    pass
+
 # TODO: Once we can determine current directory, use that to construct this
 # path:
 #import sys

vm/src/builtins.rs

@@ -818,6 +818,7 @@ pub fn make_module(ctx: &PyContext) -> PyObjectRef {
     ctx.set_attr(&py_mod, "TypeError", ctx.exceptions.type_error.clone());
     ctx.set_attr(&py_mod, "ValueError", ctx.exceptions.value_error.clone());
     ctx.set_attr(&py_mod, "IndexError", ctx.exceptions.index_error.clone());
+    ctx.set_attr(&py_mod, "ImportError", ctx.exceptions.import_error.clone());
 
     py_mod
 }

vm/src/import.rs

@@ -71,11 +71,17 @@ pub fn import(
     let module = import_module(vm, current_path, module_name)?;
     // If we're importing a symbol, look it up and use it, otherwise construct a module and return
     // that
-    let obj = match symbol {
-        Some(symbol) => module.get_item(symbol).unwrap(),
-        None => module,
-    };
-    Ok(obj)
+    if let Some(symbol) = symbol {
+        module.get_item(symbol).map_or_else(
+            || {
+                let import_error = vm.context().exceptions.import_error.clone();
+                Err(vm.new_exception(import_error, format!("cannot import name '{}'", symbol)))
+            },
+            |obj| Ok(obj),
+        )
+    } else {
+        Ok(module)
+    }
 }
 
 fn find_source(vm: &VirtualMachine, current_path: PathBuf, name: &str) -> Result<PathBuf, String> {