diff --git a/benches/lib.rs b/benches/lib.rs
index 50fff39..8dd69d0 100644
--- a/benches/lib.rs
+++ b/benches/lib.rs
@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(deprecated)]
 extern crate generator;
 extern crate test;
 
@@ -176,6 +177,6 @@ fn fnbox_bench(b: &mut Bencher) {
         let f: Box<dyn FnOnce()> = Box::new(|| {
             test::black_box(a);
         });
-        test::black_box(f);
+        let _ = test::black_box(f);
     });
 }
diff --git a/examples/cd.rs b/examples/cd.rs
index 02a2804..18a5c9b 100644
--- a/examples/cd.rs
+++ b/examples/cd.rs
@@ -1,4 +1,3 @@
-extern crate generator;
 use generator::*;
 
 #[derive(Debug)]
diff --git a/examples/fib.rs b/examples/fib.rs
index e6c778f..4c3bd79 100644
--- a/examples/fib.rs
+++ b/examples/fib.rs
@@ -1,6 +1,4 @@
-#[macro_use]
-extern crate generator;
-use generator::Gn;
+use generator::{done, Gn};
 
 fn main() {
     let g = Gn::new_scoped(|mut s| {
diff --git a/examples/get_yield.rs b/examples/get_yield.rs
index 75ea814..644b72a 100644
--- a/examples/get_yield.rs
+++ b/examples/get_yield.rs
@@ -1,4 +1,4 @@
-extern crate generator;
+#![allow(deprecated)]
 use generator::{get_yield, yield_with, Gn};
 
 fn sum(a: u32) -> u32 {
diff --git a/examples/number.rs b/examples/number.rs
index 99628f6..5ea3ed2 100644
--- a/examples/number.rs
+++ b/examples/number.rs
@@ -1,4 +1,3 @@
-extern crate generator;
 use generator::*;
 
 fn factors(n: u32) -> Generator<'static, (), u32> {
diff --git a/examples/pipe.rs b/examples/pipe.rs
index 5de6302..43d0864 100644
--- a/examples/pipe.rs
+++ b/examples/pipe.rs
@@ -1,4 +1,3 @@
-extern crate generator;
 use generator::*;
 
 fn main() {
diff --git a/examples/range.rs b/examples/range.rs
index 34b85f0..a5589db 100644
--- a/examples/range.rs
+++ b/examples/range.rs
@@ -1,6 +1,4 @@
-#[macro_use]
-extern crate generator;
-use generator::Gn;
+use generator::{done, Gn};
 
 fn main() {
     let n = 100000;
diff --git a/examples/send.rs b/examples/send.rs
index 30f0226..cbc3c39 100644
--- a/examples/send.rs
+++ b/examples/send.rs
@@ -1,8 +1,7 @@
-extern crate generator;
-
-use std::mem;
+#![allow(deprecated)]
 
 use generator::{yield_, Gn};
+use std::mem;
 
 fn sum(a: u32) -> u32 {
     let mut sum = a;
diff --git a/examples/yield_from.rs b/examples/yield_from.rs
index f26d1b8..893e6a3 100644
--- a/examples/yield_from.rs
+++ b/examples/yield_from.rs
@@ -1,4 +1,5 @@
-extern crate generator;
+#![allow(deprecated)]
+
 use generator::*;
 
 fn xrange(start: u32, end: u32) -> u32 {
diff --git a/src/gen_impl.rs b/src/gen_impl.rs
index 8f56304..ae6c56b 100644
--- a/src/gen_impl.rs
+++ b/src/gen_impl.rs
@@ -54,6 +54,7 @@ impl<A> Gn<A> {
 impl<A: Any> Gn<A> {
     /// create a new generator with default stack size
     #[cfg_attr(feature = "cargo-clippy", allow(clippy::new_ret_no_self))]
+    #[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
     pub fn new<'a, T: Any, F>(f: F) -> Generator<'a, A, T>
     where
         F: FnOnce() -> T + 'a,
@@ -62,6 +63,7 @@ impl<A: Any> Gn<A> {
     }
 
     /// create a new generator with specified stack size
+    #[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
     pub fn new_opt<'a, T: Any, F>(size: usize, f: F) -> Generator<'a, A, T>
     where
         F: FnOnce() -> T + 'a,
@@ -88,8 +90,10 @@ pub struct GeneratorImpl<'a, A, T> {
 impl<'a, A: Any, T: Any> GeneratorImpl<'a, A, T> {
     /// create a new generator with default stack size
     pub fn init_context(&mut self) {
-        self.context.para = &mut self.para as &mut dyn Any;
-        self.context.ret = &mut self.ret as &mut dyn Any;
+        unsafe {
+            *self.context.para.as_mut_ptr() = &mut self.para as &mut dyn Any;
+            *self.context.ret.as_mut_ptr() = &mut self.ret as &mut dyn Any;
+        }
     }
 }
 
@@ -353,6 +357,7 @@ impl<'a, T> Iterator for GeneratorImpl<'a, (), T> {
 
 impl<'a, A, T> fmt::Debug for GeneratorImpl<'a, A, T> {
     #[cfg(nightly)]
+    #[allow(unused_unsafe)]
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         use std::intrinsics::type_name;
         write!(
diff --git a/src/lib.rs b/src/lib.rs
index b2caec8..09018a4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,6 +10,7 @@
 #![cfg_attr(nightly, feature(thread_local))]
 // #![cfg_attr(test, deny(warnings))]
 #![deny(missing_docs)]
+#![allow(deprecated)]
 
 #[macro_use]
 extern crate log;
diff --git a/src/rt.rs b/src/rt.rs
index 765227d..4509d67 100644
--- a/src/rt.rs
+++ b/src/rt.rs
@@ -3,7 +3,7 @@
 //! generator run time context management
 //!
 use std::any::Any;
-use std::mem;
+use std::mem::MaybeUninit;
 use std::ptr;
 
 use crate::reg_context::RegContext;
@@ -48,9 +48,9 @@ pub struct Context {
     /// generator execution stack
     pub stack: Stack,
     /// passed in para for send
-    pub para: *mut dyn Any,
+    pub para: MaybeUninit<*mut dyn Any>,
     /// this is just a buffer for the return value
-    pub ret: *mut dyn Any,
+    pub ret: MaybeUninit<*mut dyn Any>,
     /// track generator ref, yield will -1, send will +1
     pub _ref: u32,
     /// propagate panic
@@ -70,8 +70,8 @@ impl Context {
         Context {
             regs: RegContext::empty(),
             stack: Stack::empty(),
-            para: unsafe { mem::MaybeUninit::uninit().assume_init() },
-            ret: unsafe { mem::MaybeUninit::uninit().assume_init() },
+            para: MaybeUninit::zeroed(),
+            ret: MaybeUninit::zeroed(),
             _ref: 1, // none zero means it's not running
             err: None,
             child: ptr::null_mut(),
@@ -85,8 +85,8 @@ impl Context {
         Context {
             regs: RegContext::empty(),
             stack: Stack::new(size),
-            para: unsafe { mem::MaybeUninit::uninit().assume_init() },
-            ret: unsafe { mem::MaybeUninit::uninit().assume_init() },
+            para: MaybeUninit::zeroed(),
+            ret: MaybeUninit::zeroed(),
             _ref: 1, // none zero means it's not running
             err: None,
             child: ptr::null_mut(),
@@ -103,11 +103,15 @@ impl Context {
 
     /// get current generator send para
     #[inline]
-    pub fn get_para<A>(&self) -> Option<A>
+    pub fn get_para<A>(&mut self) -> Option<A>
     where
         A: Any,
     {
-        let para = unsafe { &mut *self.para };
+        let para = unsafe {
+            let para_ptr = *self.para.as_mut_ptr();
+            assert!(!para_ptr.is_null());
+            &mut *para_ptr
+        };
         match para.downcast_mut::<Option<A>>() {
             Some(v) => v.take(),
             #[cold]
@@ -117,8 +121,12 @@ impl Context {
 
     /// get coroutine send para
     #[inline]
-    pub fn co_get_para<A>(&self) -> Option<A> {
-        let para = unsafe { &mut *(self.para as *mut Option<A>) };
+    pub fn co_get_para<A>(&mut self) -> Option<A> {
+        let para = unsafe {
+            let para_ptr = *self.para.as_mut_ptr();
+            debug_assert!(!para_ptr.is_null());
+            &mut *(para_ptr as *mut Option<A>)
+        };
         para.take()
     }
 
@@ -139,8 +147,12 @@ impl Context {
     /// set coroutine send para
     /// without check the data type for coroutine performance reason
     #[inline]
-    pub fn co_set_para<A>(&self, data: A) {
-        let para = unsafe { &mut *(self.para as *mut Option<A>) };
+    pub fn co_set_para<A>(&mut self, data: A) {
+        let para = unsafe {
+            let para_ptr = *self.para.as_mut_ptr();
+            debug_assert!(!para_ptr.is_null());
+            &mut *(para_ptr as *mut Option<A>)
+        };
         *para = Some(data);
     }
 
@@ -150,7 +162,11 @@ impl Context {
     where
         T: Any,
     {
-        let ret = unsafe { &mut *self.ret };
+        let ret = unsafe {
+            let ret_ptr = *self.ret.as_mut_ptr();
+            assert!(!ret_ptr.is_null());
+            &mut *ret_ptr
+        };
         match ret.downcast_mut::<Option<T>>() {
             Some(r) => *r = Some(v),
             #[cold]
@@ -162,7 +178,11 @@ impl Context {
     /// without check the data type for coroutine performance reason
     #[inline]
     pub fn co_set_ret<T>(&mut self, v: T) {
-        let ret = unsafe { &mut *(self.ret as *mut Option<T>) };
+        let ret = unsafe {
+            let ret_ptr = *self.ret.as_mut_ptr();
+            debug_assert!(!ret_ptr.is_null());
+            &mut *(ret_ptr as *mut Option<T>)
+        };
         *ret = Some(v);
     }
 }
@@ -263,6 +283,7 @@ impl ContextStack {
 #[inline]
 fn type_error<A>(msg: &str) -> ! {
     #[cfg(nightly)]
+    #[allow(unused_unsafe)]
     {
         use std::intrinsics::type_name;
         let t = unsafe { type_name::<A>() };
diff --git a/src/yield_.rs b/src/yield_.rs
index 75936bc..7e22aec 100644
--- a/src/yield_.rs
+++ b/src/yield_.rs
@@ -64,7 +64,7 @@ fn raw_yield<T: Any>(env: &ContextStack, context: &mut Context, v: T) {
 
 /// yield something without catch passed in para
 #[inline]
-// #[deprecated(since="0.5.0", note="please use `scope` instead")]
+#[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
 pub fn yield_with<T: Any>(v: T) {
     let env = ContextStack::current();
     let context = env.top();
@@ -73,7 +73,7 @@ pub fn yield_with<T: Any>(v: T) {
 
 /// get the passed in para
 #[inline]
-// #[deprecated(since="0.5.0", note="please use `scope` instead")]
+#[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
 pub fn get_yield<A: Any>() -> Option<A> {
     let context = ContextStack::current().top();
     raw_get_yield(context)
@@ -99,7 +99,7 @@ fn raw_get_yield<A: Any>(context: &mut Context) -> Option<A> {
 // this is fine, but it's totally safe that we can refer to the function block
 // since we will come back later
 #[inline]
-// #[deprecated(since="0.5.0", note="please use `scope` instead")]
+#[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
 pub fn yield_<A: Any, T: Any>(v: T) -> Option<A> {
     let env = ContextStack::current();
     let context = env.top();
@@ -108,7 +108,7 @@ pub fn yield_<A: Any, T: Any>(v: T) -> Option<A> {
 }
 
 /// `yield_from`
-// #[deprecated(since="0.5.0", note="please use `scope` instead")]
+#[deprecated(since = "0.6.18", note = "please use `scope` version instead")]
 pub fn yield_from<A: Any, T: Any>(mut g: Generator<A, T>) -> Option<A> {
     let env = ContextStack::current();
     let context = env.top();
diff --git a/tests/lib.rs b/tests/lib.rs
index 3bbacc7..cc21c91 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,3 +1,5 @@
+#![allow(deprecated)]
+
 extern crate generator;
 
 use generator::*;
@@ -480,3 +482,14 @@ fn test_re_init() {
 fn done_in_normal() {
     done!();
 }
+
+#[test]
+#[should_panic]
+fn invaild_yield_in_scope() {
+    let g = Gn::new_scoped(|_| {
+        // invalid use raw yield API with scope
+        yield_::<String, _>(());
+    });
+
+    for () in g {}
+}