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Local References

Local references have a lifecycle within the model that control how and when information is shared. The main steps in the lifecycle include:

  1. Create
  2. Set
  3. Share
  4. Clear
  5. Unshare
  6. Dispose

To illustrate this, see the example below using an IndexReference in a RealTimeString. We will explain these concepts in more detail later.

const textElement = model.root().get("text");

// Create the reference
const localCursor = model.indexReference("cursor");

// Set the initial cursor location, not shared yet

// Share the cursor, now shared.

// Clear the cursor.  You could call this when the editor loses focus.
// Other users still know you have a cursor, it's just that it now 
// has no value.  They could then, for example, remove your cursor from 
// the editor UI.

// Set the cursor again

// Unshare the cursor, no longer shared.

// Dispose of the local reference when you no longer
// need it.

Between when the reference is created and disposed, it can be shared, unshared, set and cleared multiple times. There is a distinct difference between set / clear and share / unshare. Set and clear control whether the reference currently has a value. Share and unshare determine whether you intend to share a reference (regardless of its value) with other users. For example, if I have a document open, I always intend to share my cursor, so it is always shared. My cursor may not have a value (e.g. be cleared) if my editor loses focus.

Getting Existing Local References

An existing local reference can be retrieved simply by calling the same method that was used to create it. For example:

const rtString = model.root().get("text");

// Create the reference for the first time
const localCursor = model.indexReference("cursor");

// Gets the existing reference.
const localCursor2 = model.indexReference("cursor");

console.log(localCursor === localCursor2); // true