Release v0.0.3

.semrelease/this_release

@@ -1,3 +1,5 @@
 # This file has been cleaned up post-releasing version 0.0.2.
 # Generate its content quickly using the following command:
 #   git log origin..HEAD | grep "^\s" > .semrelease/this_release
+#!VERSION=0.0.3
+- impr: Expose shared static Factory on XxHash128Hasher, XxHash3Hasher and Crc32Hasher for cached reuse via Signum.

Ddth.Signum.Tests/HasherTests.cs

@@ -11,6 +11,31 @@ public static IEnumerable<object[]> Hashers()
         yield return new object[] { (Func<IHasher>)(() => new Crc32Hasher()), 4 };
     }
 
+    [Fact]
+    public void Factory_CreatesNewInstanceOfExpectedType()
+    {
+        Assert.IsType<XxHash128Hasher>(XxHash128Hasher.Factory());
+        Assert.IsType<XxHash3Hasher>(XxHash3Hasher.Factory());
+        Assert.IsType<Crc32Hasher>(Crc32Hasher.Factory());
+
+        // Each invocation returns a distinct instance.
+        Assert.NotSame(XxHash3Hasher.Factory(), XxHash3Hasher.Factory());
+    }
+
+    [Fact]
+    public void Factory_MatchesEquivalentInlineFactory()
+    {
+        Assert.Equal(
+            Signum.ChecksumHex("hello", () => new XxHash3Hasher()),
+            Signum.ChecksumHex("hello", XxHash3Hasher.Factory));
+    }
+
+    [Fact]
+    public void XxHash128Factory_MatchesDefault()
+    {
+        Assert.Equal(Signum.ChecksumHex("hello"), Signum.ChecksumHex("hello", XxHash128Hasher.Factory));
+    }
+
     [Theory]
     [MemberData(nameof(Hashers))]
     public void Hasher_ProducesExpectedWidth(Func<IHasher> factory, int expectedWidth)

Ddth.Signum/Crc32Hasher.cs

@@ -9,6 +9,9 @@ namespace Ddth.Signum;
 /// </summary>
 public sealed class Crc32Hasher : IHasher
 {
+    /// <summary>Shared factory that creates a new <see cref="Crc32Hasher"/> instance.</summary>
+    public static readonly Func<IHasher> Factory = () => new Crc32Hasher();
+
     private readonly Crc32 _inner = new();
 
     /// <inheritdoc/>

Ddth.Signum/Signum.cs

@@ -13,7 +13,8 @@ namespace Ddth.Signum;
 /// </remarks>
 public static class Signum
 {
-    private static readonly Fingerprinter Default = new();
+    private static readonly Fingerprinter Default =
+        new(new FingerprintOptions { HasherFactory = XxHash128Hasher.Factory });
 
     private static readonly ConcurrentDictionary<Func<IHasher>, Fingerprinter> Cache = new();
 

Ddth.Signum/XxHash128Hasher.cs

@@ -8,6 +8,9 @@ namespace Ddth.Signum;
 /// </summary>
 public sealed class XxHash128Hasher : IHasher
 {
+    /// <summary>Shared factory that creates a new <see cref="XxHash128Hasher"/> instance.</summary>
+    public static readonly Func<IHasher> Factory = () => new XxHash128Hasher();
+
     private readonly XxHash128 _inner = new();
 
     /// <inheritdoc/>

Ddth.Signum/XxHash3Hasher.cs

@@ -8,6 +8,9 @@ namespace Ddth.Signum;
 /// </summary>
 public sealed class XxHash3Hasher : IHasher
 {
+    /// <summary>Shared factory that creates a new <see cref="XxHash3Hasher"/> instance.</summary>
+    public static readonly Func<IHasher> Factory = () => new XxHash3Hasher();
+
     private readonly XxHash3 _inner = new();
 
     /// <inheritdoc/>

README.md

@@ -70,8 +70,10 @@ The library ships three hashers (all from `System.IO.Hashing`): `XxHash128Hasher
 `FingerprintOptions.HasherFactory`, or via the optional parameter on the `Signum` helper:
 
 ```csharp
-// Use a built-in hasher through the static helper:
-string hex = Signum.ChecksumHex(myObject, () => new XxHash3Hasher());
+// Use a built-in hasher through the static helper. Each hasher exposes a shared
+// `Factory` delegate, which lets the Signum helper cache and reuse a single
+// Fingerprinter per hasher type:
+string hex = Signum.ChecksumHex(myObject, XxHash3Hasher.Factory);
 ```
 
 Provide your own `IHasher` to use any other algorithm: