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Most APIs in Optimizely CMS return read-only instances of objects, such as `IContentLoader.Get<TContentData>` which return a read-only `IContent` instance.

To make changes to read-only instances, create a writable clone with the `CreateWritableClone` method, which has the following advantages:

  • **Reduce memory consumption** – Threads serving Web requests get the same instance of an object, which effectively reduces the amount of short-lived objects that are created.

  • **Improve performance** – Returning shared read-only instances offers better performance.

  • **Cleaner architecture** – This simplifies the implementation because you cannot make changes to an instance of an object shared with other threads.

Classes that have the read-only support implements the `IReadOnly<T>` interface, which is defined as follows:



The lifecycle of a typical `IContent` instance is as follows:

  1. Create the `IContent` instance as mutable (which means writeable).

  2. Populate the `IContent` instance with property values.

  3. Call the `IReadOnly.MakeReadOnly` method to ensure that any contained objects are made read-only. The object is immutable for the remainder of its lifetime.

  4. Add the object to the cache.