Docs: Simplify example on specification builder extensiblity (#249)

* Docs: Simply example on specification builder extensiblity

* Docs: Apply code suggestions from @fiseni (#247)

Co-authored-by: Michaël Vittorelli <[email protected]>

Author: vittorelli

docs/extensions/create-specification-builder.md renamed to docs/extensions/extend-specification-builder.md

@@ -6,7 +6,7 @@ nav_order: 2
 ---
 
 
-# How to create your own specification builder
+# How to add extensions to the specification builder
 
 The specification builder from `Ardalis.Specification` is extensible by design. In fact, the methods you can use out of the box are implemented as extension methods themselves (check out the [source code](https://github.com/ardalis/Specification/blob/main/Specification/src/Ardalis.Specification/Builder/SpecificationBuilderExtensions.cs)). Your project might have requirements that cannot be satisfied by the existing toolset of course, or you might want to simplify repetitive code in several specification constructors. Whatever your case, enhancing the default builder is easy by creating your own extension methods.
 
@@ -87,28 +87,19 @@ public class Repository<T>
 }
 ```
 
-Finally, we need to take care of some plumbing to implement the `.GetCacheTTL` and `.SetCacheTTL` methods that we've used in the example repository and builder extension. The class below uses `ConditionalWeakTable` to do the trick. Another solution is to create a base class that inherits from `Specification<T>`.
+Finally, we need to take care of some plumbing to implement the `.GetCacheTTL` and `.SetCacheTTL` methods that we've used in the example repository and builder extension.
 
 ````csharp
 public static class SpecificationExtensions
 {
-    private static readonly ConditionalWeakTable<object, CacheOptions> SpecificationCacheOptions = new();
-
-    public static void SetCacheTTL<T>(this ISpecification<T> spec, TimeSpan ttl)
+    public static void SetCacheTTL<T>(this ISpecification<T> spec, TimeSpan timeToLive)
     {
-        SpecificationCacheOptions.AddOrUpdate(spec, new CacheOptions() { TTL = ttl });
+        spec.Items["CacheTTL"] = timeToLive;
     }
-
     public static TimeSpan GetCacheTTL<T>(this ISpecification<T> spec)
     {
-        var opts = SpecificationCacheOptions.GetOrCreateValue(spec);
-        return opts?.TTL ?? TimeSpan.MaxValue;
-    }
-
-    // ConditionalWeakTable need reference types; TimeSpan is a struct
-    private class CacheOptions
-    {
-        public TimeSpan TTL { get; set; }
+        spec.Items.TryGetValue("CacheTTL", out var ttl);
+        return (ttl as TimeSpan?) ?? TimeSpan.MaxValue;
     }
 }
 ````

docs/features/caching.md

@@ -23,6 +23,6 @@ public class CustomerByNameWithStoresSpec : Specification<Customer>, ISingleResu
     }
 ```
 
-The `.EnableCache` method takes in two parameters: the name of the specification and the parameters of the specification. It does not include any parameters to control how the cache should behave (e.g. absolute expiration date, expiration tokens, ...). However, one could create an extension method to the specification builder in order to add this information ([example](../extensions/create-specification-builder.md)).
+The `.EnableCache` method takes in two parameters: the name of the specification and the parameters of the specification. It does not include any parameters to control how the cache should behave (e.g. absolute expiration date, expiration tokens, ...). However, one could create an extension method to the specification builder in order to add this information ([example](../extensions/extend-specification-builder.md)).
 
 Implementing caching will also require infrastructure such as a CachedRepository, an example of which is given in [the sample](https://github.com/ardalis/Specification/blob/2605202df4d8e40fe388732db6d8f7a3754fcc2b/sample/Ardalis.SampleApp.Infrastructure/Data/CachedCustomerRepository.cs#L13) on GitHub. The `EnableCache` method is used to inform the cache implementation that caching should be used, and to configure the `CacheKey` based on the arguments supplied.