Replace existing Comm on open

ipywidgets_bokeh/src/manager.ts

@@ -3,7 +3,7 @@
 import * as controls from "@jupyter-widgets/controls"
 
 import {HTMLManager} from "@jupyter-widgets/html-manager"
-import {WidgetModel, WidgetView, IModelOptions, IClassicComm, shims} from "@jupyter-widgets/base"
+import {WidgetModel, WidgetView, IModelOptions, shims} from "@jupyter-widgets/base"
 import {IState, IManagerState} from "@jupyter-widgets/base-manager"
 
 import {Kernel, KernelManager, ServerConnection} from "@jupyterlab/services"
@@ -131,13 +131,12 @@
       const comm_wrapper = new shims.services.Comm(comm)
       if (model == null) {
         this.handle_comm_open(comm_wrapper, msg).then((model) => {
 	  if (model != null && !model.comm_live) {
             const comm_wrapper = new shims.services.Comm(comm)
             this._attach_comm(comm_wrapper, model)
 	  }
         })
-      }
-      if (model != null && !model.comm_live) {
+      } else {
         this._attach_comm(comm_wrapper, model)
       }
       this._model_objs.delete(msg.content.comm_id)
@@ -191,17 +190,19 @@
   }
 
   override async _create_comm(target_name: string, model_id: string, data?: any, metadata?: any,
-      buffers?: ArrayBuffer[] | ArrayBufferView[]): Promise<IClassicComm> {
+      buffers?: ArrayBuffer[] | ArrayBufferView[]): Promise<shims.services.Comm> {
     const comm = (() => {
       const key = target_name + model_id
-      const comm = this._comms.get(key)
-      if (comm != null)
-        return comm
-      else {
-        const comm = this.kernel.createComm(target_name, model_id)
+      let comm = this._comms.get(key)
+      if (comm == null) {
+        if (this.kernel.hasComm(model_id)) {
+	  comm = (this.kernel as any)._comms.get(model_id)
+        } else {
+          comm = this.kernel.createComm(target_name, model_id)
+        }
         this._comms.set(key, comm)
-        return comm
       }
+      return comm
     })()
     comm.open(data, metadata, buffers)
     return new shims.services.Comm(comm)