diff --git a/src/api/call_fn.rs b/src/api/call_fn.rs
index bcbcf608..5c48712f 100644
--- a/src/api/call_fn.rs
+++ b/src/api/call_fn.rs
@@ -18,9 +18,9 @@ use std::{
 #[non_exhaustive]
 #[must_use]
 pub struct CallFnOptions<'t> {
-    /// A value for binding to the `this` pointer (if any).
+    /// A value for binding to the `this` pointer (if any). Default [`None`].
     pub this_ptr: Option<&'t mut Dynamic>,
-    /// The custom state of this evaluation run (if any), overrides [`Engine::default_tag`].
+    /// The custom state of this evaluation run (if any), overrides [`Engine::default_tag`]. Default [`None`].
     pub tag: Option<Dynamic>,
     /// Evaluate the [`AST`] to load necessary modules before calling the function? Default `true`.
     pub eval_ast: bool,
@@ -172,13 +172,13 @@ impl Engine {
         args.parse(&mut arg_values);
 
         self._call_fn(
-            options,
             scope,
             &mut GlobalRuntimeState::new(self),
             &mut Caches::new(),
             ast,
             name.as_ref(),
             arg_values.as_mut(),
+            options,
         )
         .and_then(|result| {
             // Bail out early if the return type needs no cast
@@ -207,13 +207,13 @@ impl Engine {
     #[inline(always)]
     pub(crate) fn _call_fn(
         &self,
-        options: CallFnOptions,
         scope: &mut Scope,
         global: &mut GlobalRuntimeState,
         caches: &mut Caches,
         ast: &AST,
         name: &str,
         arg_values: &mut [Dynamic],
+        options: CallFnOptions,
     ) -> RhaiResult {
         let statements = ast.statements();
 
diff --git a/src/api/deprecated.rs b/src/api/deprecated.rs
index 4beaca5b..72cfe1ad 100644
--- a/src/api/deprecated.rs
+++ b/src/api/deprecated.rs
@@ -167,13 +167,13 @@ impl Engine {
         };
 
         self._call_fn(
-            options,
             scope,
             &mut crate::eval::GlobalRuntimeState::new(self),
             &mut crate::eval::Caches::new(),
             ast,
             name.as_ref(),
             arg_values.as_mut(),
+            options,
         )
     }
     /// Register a custom fallible function with the [`Engine`].
diff --git a/src/api/eval.rs b/src/api/eval.rs
index 30880056..7955d1c0 100644
--- a/src/api/eval.rs
+++ b/src/api/eval.rs
@@ -250,9 +250,9 @@ impl Engine {
                 #[cfg(feature = "debugging")]
                 if self.is_debugger_registered() {
                     global.debugger_mut().status = crate::eval::DebuggerStatus::Terminate;
-                    let mut this = Dynamic::NULL;
+                    let mut this_ptr = Dynamic::NULL;
                     let node = &crate::ast::Stmt::Noop(Position::NONE);
-                    self.run_debugger(global, caches, scope, &mut this, node)?;
+                    self.run_debugger(global, caches, scope, &mut this_ptr, node)?;
                 }
                 Ok(r)
             })
diff --git a/src/api/options.rs b/src/api/options.rs
index d5aeef90..325dbbcb 100644
--- a/src/api/options.rs
+++ b/src/api/options.rs
@@ -22,7 +22,7 @@ bitflags! {
         /// Is looping allowed?
         const LOOPING = 0b_0000_0010_0000;
         /// Is variables shadowing allowed?
-        const SHADOW = 0b_0000_0100_0000;
+        const SHADOWING = 0b_0000_0100_0000;
         /// Strict variables mode?
         const STRICT_VAR = 0b_0000_1000_0000;
         /// Raise error if an object map property does not exist?
@@ -43,7 +43,7 @@ impl LangOptions {
             | Self::SWITCH_EXPR
             | Self::STMT_EXPR
             | Self::LOOPING
-            | Self::SHADOW
+            | Self::SHADOWING
             | Self::FAST_OPS
             | {
                 #[cfg(not(feature = "no_function"))]
@@ -148,12 +148,12 @@ impl Engine {
     #[inline(always)]
     #[must_use]
     pub const fn allow_shadowing(&self) -> bool {
-        self.options.contains(LangOptions::SHADOW)
+        self.options.contains(LangOptions::SHADOWING)
     }
     /// Set whether variables shadowing is allowed.
     #[inline(always)]
     pub fn set_allow_shadowing(&mut self, enable: bool) -> &mut Self {
-        self.options.set(LangOptions::SHADOW, enable);
+        self.options.set(LangOptions::SHADOWING, enable);
         self
     }
     /// Is strict variables mode enabled?
diff --git a/src/api/run.rs b/src/api/run.rs
index 8ecf8b2e..4ed9caf5 100644
--- a/src/api/run.rs
+++ b/src/api/run.rs
@@ -131,9 +131,9 @@ impl Engine {
                 #[cfg(feature = "debugging")]
                 if self.is_debugger_registered() {
                     global.debugger_mut().status = crate::eval::DebuggerStatus::Terminate;
-                    let mut this = crate::Dynamic::NULL;
+                    let mut this_ptr = crate::Dynamic::NULL;
                     let node = &crate::ast::Stmt::Noop(crate::Position::NONE);
-                    self.run_debugger(global, caches, scope, &mut this, node)?;
+                    self.run_debugger(global, caches, scope, &mut this_ptr, node)?;
                 }
                 Ok(())
             })
diff --git a/src/eval/chaining.rs b/src/eval/chaining.rs
index d2008802..e4baa002 100644
--- a/src/eval/chaining.rs
+++ b/src/eval/chaining.rs
@@ -392,13 +392,19 @@ impl Engine {
                 self.run_debugger(global, caches, scope, this_ptr, lhs)?;
                 self.track_operation(global, *var_pos)?;
 
-                let mut target = self.search_namespace(global, caches, scope, this_ptr, lhs)?;
-
-                let obj_ptr = &mut target;
-                let mut this = Dynamic::NULL;
+                let target = &mut self.search_namespace(global, caches, scope, this_ptr, lhs)?;
+                let mut this_ptr = Dynamic::NULL;
 
                 self.eval_dot_index_chain_raw(
-                    global, caches, &mut this, lhs, expr, obj_ptr, rhs, idx_values, new_val,
+                    global,
+                    caches,
+                    &mut this_ptr,
+                    lhs,
+                    expr,
+                    target,
+                    rhs,
+                    idx_values,
+                    new_val,
                 )
             }
             // {expr}.??? = ??? or {expr}[???] = ???
diff --git a/src/eval/stmt.rs b/src/eval/stmt.rs
index 04681410..99b90f44 100644
--- a/src/eval/stmt.rs
+++ b/src/eval/stmt.rs
@@ -882,9 +882,9 @@ impl Engine {
         scope: &mut Scope,
         statements: &[Stmt],
     ) -> RhaiResult {
-        let mut this = Dynamic::NULL;
+        let mut this_ptr = Dynamic::NULL;
 
-        self.eval_stmt_block(global, caches, scope, &mut this, statements, false)
+        self.eval_stmt_block(global, caches, scope, &mut this_ptr, statements, false)
             .or_else(|err| match *err {
                 ERR::Return(out, ..) => Ok(out),
                 ERR::LoopBreak(..) => {
diff --git a/src/func/call.rs b/src/func/call.rs
index a425e845..7a0fafec 100644
--- a/src/func/call.rs
+++ b/src/func/call.rs
@@ -429,7 +429,7 @@ impl Engine {
                 };
                 if trigger {
                     let scope = &mut Scope::new();
-                    let mut this = Dynamic::NULL;
+                    let mut this_ptr = Dynamic::NULL;
                     let node = crate::ast::Stmt::Noop(pos);
                     let node = (&node).into();
                     let event = match _result {
@@ -438,7 +438,7 @@ impl Engine {
                     };
 
                     if let Err(err) =
-                        self.run_debugger_raw(global, caches, scope, &mut this, node, event)
+                        self.run_debugger_raw(global, caches, scope, &mut this_ptr, node, event)
                     {
                         _result = Err(err);
                     }
@@ -681,9 +681,9 @@ impl Engine {
 
                     auto_restore!(args = (_args) if swap => move |a| backup.restore_first_arg(a));
 
-                    let mut this = Dynamic::NULL;
+                    let mut this_ptr = Dynamic::NULL;
 
-                    self.call_script_fn(global, caches, scope, &mut this, func, args, true, pos)
+                    self.call_script_fn(global, caches, scope, &mut this_ptr, func, args, true, pos)
                 }
                 .map(|r| (r, false));
             }
@@ -1248,7 +1248,7 @@ impl Engine {
         pos: Position,
     ) -> RhaiResult {
         let mut arg_values = FnArgsVec::with_capacity(args_expr.len());
-        let mut args = FnArgsVec::with_capacity(args_expr.len());
+        let args = &mut FnArgsVec::with_capacity(args_expr.len());
         let mut first_arg_value = None;
 
         if args_expr.is_empty() {
@@ -1366,16 +1366,14 @@ impl Engine {
         match func {
             #[cfg(not(feature = "no_function"))]
             Some(f) if f.is_script() => {
-                let fn_def = f.get_script_fn_def().expect("script-defined function");
-                let new_scope = &mut Scope::new();
-                let mut this = Dynamic::NULL;
+                let f = f.get_script_fn_def().expect("script-defined function");
+                let scope = &mut Scope::new();
+                let mut this_ptr = Dynamic::NULL;
 
                 let orig_source = mem::replace(&mut global.source, module.id_raw().cloned());
                 auto_restore!(global => move |g| g.source = orig_source);
 
-                self.call_script_fn(
-                    global, caches, new_scope, &mut this, fn_def, &mut args, true, pos,
-                )
+                self.call_script_fn(global, caches, scope, &mut this_ptr, f, args, true, pos)
             }
 
             Some(f) if f.is_plugin_fn() => {
@@ -1388,7 +1386,7 @@ impl Engine {
                 if !f.is_pure() && !args.is_empty() && args[0].is_read_only() {
                     Err(ERR::ErrorNonPureMethodCallOnConstant(fn_name.to_string(), pos).into())
                 } else {
-                    f.call(context, &mut args)
+                    f.call(context, args)
                         .and_then(|r| self.check_data_size(r, pos))
                 }
             }
@@ -1400,19 +1398,19 @@ impl Engine {
                 } else {
                     None
                 };
-                func(context, &mut args).and_then(|r| self.check_data_size(r, pos))
+                func(context, args).and_then(|r| self.check_data_size(r, pos))
             }
 
             Some(f) => unreachable!("unknown function type: {:?}", f),
 
             None => {
                 let sig = if namespace.is_empty() {
-                    self.gen_fn_call_signature(fn_name, &args)
+                    self.gen_fn_call_signature(fn_name, args)
                 } else {
                     format!(
                         "{namespace}{}{}",
                         crate::tokenizer::Token::DoubleColon.literal_syntax(),
-                        self.gen_fn_call_signature(fn_name, &args)
+                        self.gen_fn_call_signature(fn_name, args)
                     )
                 };
 
diff --git a/src/parser.rs b/src/parser.rs
index 12271bbe..3a28f38a 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -2890,9 +2890,8 @@ impl Engine {
                     will_shadow,
                 };
                 let caches = &mut Caches::new();
-                let mut this = Dynamic::NULL;
-
-                let context = EvalContext::new(self, global, caches, stack, &mut this);
+                let mut this_ptr = Dynamic::NULL;
+                let context = EvalContext::new(self, global, caches, stack, &mut this_ptr);
 
                 match filter(false, info, context) {
                     Ok(true) => (),