Delay from_list tuple create in import

src/main.rs

@@ -317,7 +317,7 @@ fn run_rustpython(vm: &VirtualMachine, matches: &ArgMatches) -> PyResult<()> {
     vm.get_attribute(vm.sys_module.clone(), "modules")?
         .set_item("__main__", main_module, vm)?;
 
-    let site_result = vm.import("site", &vm.ctx.new_tuple(vec![]), 0);
+    let site_result = vm.import("site", &[], 0);
 
     if site_result.is_err() {
         warn!(
@@ -366,7 +366,7 @@ fn run_command(vm: &VirtualMachine, scope: Scope, source: String) -> PyResult<()
 
 fn run_module(vm: &VirtualMachine, module: &str) -> PyResult<()> {
     debug!("Running module {}", module);
-    let runpy = vm.import("runpy", &vm.ctx.new_tuple(vec![]), 0)?;
+    let runpy = vm.import("runpy", &[], 0)?;
     let run_module_as_main = vm.get_attribute(runpy, "_run_module_as_main")?;
     vm.invoke(&run_module_as_main, vec![vm.new_str(module.to_owned())])?;
     Ok(())

vm/src/frame.rs

@@ -539,11 +539,7 @@ impl Frame {
         level: usize,
     ) -> FrameResult {
         let module = module.clone().unwrap_or_default();
-        let from_list = symbols
-            .iter()
-            .map(|symbol| vm.ctx.new_str(symbol.to_string()))
-            .collect();
-        let module = vm.import(&module, &vm.ctx.new_tuple(from_list), level)?;
+        let module = vm.import(&module, symbols, level)?;
 
         self.push_value(module);
         Ok(None)

vm/src/import.rs

@@ -26,8 +26,7 @@ pub fn init_importlib(vm: &VirtualMachine, external: bool) -> PyResult {
             vm.get_attribute(importlib.clone(), "_install_external_importers")?;
         vm.invoke(&install_external, vec![])?;
         // Set pyc magic number to commit hash. Should be changed when bytecode will be more stable.
-        let importlib_external =
-            vm.import("_frozen_importlib_external", &vm.ctx.new_tuple(vec![]), 0)?;
+        let importlib_external = vm.import("_frozen_importlib_external", &[], 0)?;
         let mut magic = get_git_revision().into_bytes();
         magic.truncate(4);
         if magic.len() != 4 {

vm/src/obj/objmodule.rs

@@ -74,7 +74,7 @@ impl PyModuleRef {
     }
 
     fn repr(self, vm: &VirtualMachine) -> PyResult {
-        let importlib = vm.import("_frozen_importlib", &vm.ctx.new_tuple(vec![]), 0)?;
+        let importlib = vm.import("_frozen_importlib", &[], 0)?;
         let module_repr = vm.get_attribute(importlib, "_module_repr")?;
         vm.invoke(&module_repr, vec![self.into_object()])
     }

vm/src/stdlib/io.rs

@@ -648,7 +648,7 @@ pub fn io_open(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
         }
     };
 
-    let io_module = vm.import("_io", &vm.ctx.new_tuple(vec![]), 0)?;
+    let io_module = vm.import("_io", &[], 0)?;
 
     // Construct a FileIO (subclass of RawIOBase)
     // This is subsequently consumed by a Buffered Class.

vm/src/vm.rs

@@ -260,7 +260,7 @@ impl VirtualMachine {
 
     pub fn try_class(&self, module: &str, class: &str) -> PyResult<PyClassRef> {
         let class = self
-            .get_attribute(self.import(module, &self.ctx.new_tuple(vec![]), 0)?, class)?
+            .get_attribute(self.import(module, &[], 0)?, class)?
             .downcast()
             .expect("not a class");
         Ok(class)
@@ -268,7 +268,7 @@ impl VirtualMachine {
 
     pub fn class(&self, module: &str, class: &str) -> PyClassRef {
         let module = self
-            .import(module, &self.ctx.new_tuple(vec![]), 0)
+            .import(module, &[], 0)
             .unwrap_or_else(|_| panic!("unable to import {}", module));
         let class = self
             .get_attribute(module.clone(), class)
@@ -461,12 +461,10 @@ impl VirtualMachine {
         Ok(self.new_str(ascii))
     }
 
-    pub fn import(&self, module: &str, from_list: &PyObjectRef, level: usize) -> PyResult {
+    pub fn import(&self, module: &str, from_list: &[String], level: usize) -> PyResult {
         // if the import inputs seem weird, e.g a package import or something, rather than just
         // a straight `import ident`
-        let weird = module.contains('.')
-            || level != 0
-            || objbool::boolval(self, from_list.clone()).unwrap_or(true);
+        let weird = module.contains('.') || level != 0 || !from_list.is_empty();
 
         let cached_module = if weird {
             None
@@ -490,13 +488,19 @@ impl VirtualMachine {
                 } else {
                     (self.get_none(), self.get_none())
                 };
+                let from_list = self.ctx.new_tuple(
+                    from_list
+                        .iter()
+                        .map(|name| self.new_str(name.to_string()))
+                        .collect(),
+                );
                 self.invoke(
                     &import_func,
                     vec![
                         self.new_str(module.to_owned()),
                         globals,
                         locals,
-                        from_list.clone(),
+                        from_list,
                         self.ctx.new_int(level),
                     ],
                 )