#### [PromptPlus](PromptPlus.md 'PromptPlus') ### [PromptPlusLibrary](PromptPlusLibrary.md 'PromptPlusLibrary') ## IHistory Interface Provides a fluent API for adding, reading, and managing persisted history entries\. ```csharp public interface IHistory ``` ### Methods ## IHistory\.AddHistory\(string, Nullable\\) Method Adds an entry to history\. ```csharp PromptPlusLibrary.IHistory AddHistory(string value, System.Nullable timeout=null); ``` #### Parameters `value` [System\.String](https://learn.microsoft.com/en-us/dotnet/api/system.string 'System\.String') The value to store in history\. `timeout` [System\.Nullable<](https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1 'System\.Nullable\`1')[System\.TimeSpan](https://learn.microsoft.com/en-us/dotnet/api/system.timespan 'System\.TimeSpan')[>](https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1 'System\.Nullable\`1') Optional lifetime for the entry\. After the timeout expires, the entry may be removed depending on the implementation\. If `null`, no expiration is applied\. #### Returns [IHistory](IHistory.md 'PromptPlusLibrary\.IHistory') The current [IHistory](IHistory.md 'PromptPlusLibrary\.IHistory') instance for fluent chaining\. ## IHistory\.ReadHistory\\(\) Method Reads all history entries and deserializes them to the specified type\. ```csharp System.Collections.Generic.IList ReadHistory(); ``` #### Type parameters `T` The type used to deserialize history entries\. #### Returns [System\.Collections\.Generic\.IList<](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.ilist-1 'System\.Collections\.Generic\.IList\`1')[T](IHistory.md#PromptPlusLibrary.IHistory.ReadHistory_T_().T 'PromptPlusLibrary\.IHistory\.ReadHistory\\(\)\.T')[>](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.ilist-1 'System\.Collections\.Generic\.IList\`1') A list of deserialized history entries\. ## IHistory\.Remove\(\) Method Removes persisted history, such as deleting the backing store or clearing all entries\. ```csharp void Remove(); ``` ## IHistory\.Save\(\) Method Persists in\-memory history entries to durable storage\. ```csharp void Save(); ```