From 81c9cfaae55b103d49fed68310ddae1cadc97132 Mon Sep 17 00:00:00 2001
From: Christian Krause <christian.krause@mailbox.org>
Date: Fri, 26 Aug 2022 08:49:44 +0200
Subject: [PATCH 1/2] Expand on DynDigest example in README

---
 README.md | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index bc3e5d09..2b7963ab 100644
--- a/README.md
+++ b/README.md
@@ -175,20 +175,38 @@ hash_password::<Sha512>("my_password", "abcd", &mut buf2);
 If you want to use hash functions with trait objects, you can use the [`DynDigest`] trait:
 
 ```rust
-use sha2::{Sha256, Sha512, digest::DynDigest};
+use digest::DynDigest;
 
+// dynamic hash function
 fn dyn_hash(hasher: &mut dyn DynDigest, data: &[u8]) -> Box<[u8]> {
     hasher.update(data);
     hasher.finalize_reset()
 }
 
-let mut sha256_hasher = Sha256::default();
-let mut sha512_hasher = Sha512::default();
+// something like this when parsing user input, CLI arguments, etc.
+// DynDigest needs to be boxed here
+fn cli2digest(s: &str) -> Box<dyn DynDigest> {
+    match s {
+        "md5" => Box::new(md5::Md5::default()),
+        "sha1" => Box::new(sha1::Sha1::default()),
+        "sha224" => Box::new(sha2::Sha224::default()),
+        "sha256" => Box::new(sha2::Sha256::default()),
+        "sha384" => Box::new(sha2::Sha384::default()),
+        "sha512" => Box::new(sha2::Sha512::default()),
+        _ => unimplemented!("unsupported digest: {}", s),
+    }
+}
+
+let mut hasher1 = cli2digest("md5");
+let mut hasher2 = cli2digest("sha512");
+
+// the `&mut *hasher` is to DerefMut the value out of the Box
+// this is equivalent to `DerefMut::deref_mut(&mut hasher)`
 
-let hash1 = dyn_hash(&mut sha256_hasher, b"foo");
-let hash2 = dyn_hash(&mut sha256_hasher, b"bar");
-let hash3 = dyn_hash(&mut sha512_hasher, b"foo");
-let hash4 = dyn_hash(&mut sha512_hasher, b"bar");
+// can be reused due to `finalize_reset()`
+let hash1_1 = dyn_hash(&mut *hasher1, b"foo");
+let hash1_2 = dyn_hash(&mut *hasher1, b"bar");
+let hash2_1 = dyn_hash(&mut *hasher2, b"foo");
 ```
 
 ## License

From 8515ab0ae2fbd7c3d995305c0bdfe3a54f51b8b5 Mon Sep 17 00:00:00 2001
From: Artyom Pavlov <newpavlov@gmail.com>
Date: Fri, 26 Aug 2022 15:14:43 +0000
Subject: [PATCH 2/2] Minor modification of DynDigest example

---
 README.md | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/README.md b/README.md
index 2b7963ab..678c8bb4 100644
--- a/README.md
+++ b/README.md
@@ -177,15 +177,15 @@ If you want to use hash functions with trait objects, you can use the [`DynDiges
 ```rust
 use digest::DynDigest;
 
-// dynamic hash function
-fn dyn_hash(hasher: &mut dyn DynDigest, data: &[u8]) -> Box<[u8]> {
+// Dynamic hash function
+fn use_hasher(hasher: &mut dyn DynDigest, data: &[u8]) -> Box<[u8]> {
     hasher.update(data);
     hasher.finalize_reset()
 }
 
-// something like this when parsing user input, CLI arguments, etc.
-// DynDigest needs to be boxed here
-fn cli2digest(s: &str) -> Box<dyn DynDigest> {
+// You can use something like this when parsing user input, CLI arguments, etc.
+// DynDigest needs to be boxed here, since function return should be sized.
+fn select_hasher(s: &str) -> Box<dyn DynDigest> {
     match s {
         "md5" => Box::new(md5::Md5::default()),
         "sha1" => Box::new(sha1::Sha1::default()),
@@ -197,16 +197,16 @@ fn cli2digest(s: &str) -> Box<dyn DynDigest> {
     }
 }
 
-let mut hasher1 = cli2digest("md5");
-let mut hasher2 = cli2digest("sha512");
+let mut hasher1 = select_hasher("md5");
+let mut hasher2 = select_hasher("sha512");
 
 // the `&mut *hasher` is to DerefMut the value out of the Box
 // this is equivalent to `DerefMut::deref_mut(&mut hasher)`
 
 // can be reused due to `finalize_reset()`
-let hash1_1 = dyn_hash(&mut *hasher1, b"foo");
-let hash1_2 = dyn_hash(&mut *hasher1, b"bar");
-let hash2_1 = dyn_hash(&mut *hasher2, b"foo");
+let hash1_1 = use_hasher(&mut *hasher1, b"foo");
+let hash1_2 = use_hasher(&mut *hasher1, b"bar");
+let hash2_1 = use_hasher(&mut *hasher2, b"foo");
 ```
 
 ## License