Added property current_widget and method activate

ipylab/connection.py

@@ -4,13 +4,18 @@
 from __future__ import annotations
 
 import uuid
-from typing import Generic, TypeVar
+from typing import TYPE_CHECKING, Generic, TypeVar
 
 from ipywidgets import register
 from traitlets import Bool, Unicode
 
 from ipylab.asyncwidget import AsyncWidgetBase
 
+if TYPE_CHECKING:
+    from asyncio import Task
+
+    from ipylab._compat.typing import Self
+
 T = TypeVar("T", bound="Connection")
 
 
@@ -57,7 +62,7 @@ class Connection(AsyncWidgetBase, Generic[T]):
     _connections: dict[str, T] = {}  # noqa RUF012
     _model_name = Unicode("ConnectionModel").tag(sync=True)
     cid = Unicode(read_only=True, help="connection id").tag(sync=True)
-    id = Unicode(allow_none=True, read_only=True, help="id of the disposable if it has one")
+    id = Unicode("", read_only=True, help="id of the object if it has one").tag(sync=True)
     _dispose = Bool(read_only=True).tag(sync=True)
     _basename = None
 
@@ -80,7 +85,7 @@ def __init__(self, *, cid: str, model_id=None, id: str | None = None, **kwgs):
         if self._async_widget_base_init_complete:
             return
         self.set_trait("cid", cid)
-        self.set_trait("id", id)
+        self.set_trait("id", id or "")
         super().__init__(model_id=model_id, **kwgs)
 
     def __str__(self):
@@ -130,6 +135,11 @@ def get_existing_connection(cls, *name_or_id: str, quiet=False):
 class MainAreaConnection(Connection):
     CID_PREFIX = "ipylab MainArea"
 
-    def activate(self):
+    def activate(self) -> Task[Self]:
         self._check_closed()
-        return self.app.shell.execute_method("activateById", self.id)
+
+        async def activate_():
+            self.app.shell.execute_method("activateById", self.id)
+            return self
+
+        return self.to_task(activate_())

ipylab/jupyterfrontend.py

@@ -7,6 +7,7 @@
 
 from traitlets import Dict, Instance, Tuple, Unicode
 
+from ipylab import MainAreaConnection
 from ipylab.asyncwidget import AsyncWidgetBase, Transform, pack, pack_code, register, widget_serialization
 from ipylab.commands import CommandRegistry
 from ipylab.dialog import Dialog, FileDialog
@@ -38,6 +39,12 @@ class JupyterFrontEnd(AsyncWidgetBase):
     shell = Instance(Shell, (), read_only=True)
     session_manager = Instance(SessionManager, (), read_only=True)
 
+    @property
+    def current_widget(self):
+        """A connection to the current widget in the shell."""
+        id_ = self.current_widget_id
+        return MainAreaConnection(cid=MainAreaConnection.to_cid(id_), id=id_)
+
     def _init_python_backend(self):
         "Run by the Ipylab python backend."
         # This is called in a separate kernel started by the JavaScript frontend

src/widgets/connection.ts

@@ -6,28 +6,44 @@ import { ObjectHash } from 'backbone';
 import { IpylabModel } from './ipylab';
 
 /**
- * Maintain a connection to any object by using a cid.
+ * Provides a connection from any object reachable here to one or more Python backends.
+ *
+ * Typically the object is registered first via the method `registerConnection` with a cid
+ * In Python The `cid` is passed when creating a new Connection.
+ *
+ * The object is set as the base. If the object is disposable, the ConnectionModel will
+ * also close when the object is disposed.
  */
 export class ConnectionModel extends IpylabModel {
   async initialize(attributes: ObjectHash, options: any): Promise<void> {
-    super.initialize(attributes, {
-      ...options,
-      base: this.getConnection(this.get('cid'))
-    });
-    this.base.disposed.connect(() => {
-      if (!this.get('_dispose')) {
-        this.close();
-      }
-    });
-    this.listenTo(this, 'change:_dispose', () => this.base.dispose());
+    let base;
+    const cid = this.get('cid');
+    const id = this.get('id');
+    try {
+      base = this.getConnection(cid, id);
+    } catch {}
+    super.initialize(attributes, { ...options, base });
+    if (base) {
+      this.base.disposed.connect(() => this.close());
+      this.on('change:_dispose', this.dispose, this);
+    } else {
+      console.log(
+        `Failed to get connection for cid='${cid}' id='${id}' so closing...`
+      );
+      this.close();
+    }
   }
 
   close(comm_closed?: boolean): Promise<void> {
     if (this.base?.ipylabDisposeOnClose) {
       delete this.base.ipylabDisposeOnClose;
-      this.base.dispose();
+      this.dispose();
     }
-    return super.close(comm_closed);
+    return super.close((comm_closed || this.get('_dispose')) ?? false);
+  }
+
+  dispose() {
+    this.base?.dispose();
   }
 
   /**

src/widgets/ipylab.ts

@@ -57,14 +57,13 @@ export class IpylabModel extends WidgetModel {
   initialize(attributes: ObjectHash, options: any): void {
     super.initialize(attributes, options);
     this.set('kernelId', this.kernelId);
-    this.on('msg:custom', this._onCustomMessage.bind(this));
+    this.on('msg:custom', this._onCustomMessage, this);
     this.save_changes();
     const msg = `ipylab ${this.get('_model_name')} ready for operations`;
     this.send({ init: msg });
     onKernelLost(this.kernel, this.close, this);
     if (typeof options.base === 'object') {
       this._base = options.base;
-      delete options.base;
     } else {
       const basename = this.get('_basename');
       this._base = basename
@@ -240,7 +239,7 @@ export class IpylabModel extends WidgetModel {
     if (value.slice(0, 10) === 'IPY_MODEL_') {
       const model = await unpack_models(value, this.widget_manager);
       if (model.model_name === IpylabModel.connection_model_name) {
-        const widget = this.getConnection(model.cid);
+        const widget = this.getConnection(model.get('cid'), model.get('id'));
         if (!(widget instanceof Widget)) {
           throw new Error(`Failed to get a lumio widget for: ${value}`);
         }
@@ -390,11 +389,11 @@ export class IpylabModel extends WidgetModel {
    * @param cid Get an object that has been registered as a connection.
    * @returns
    */
-  getConnection(cid: string): any {
+  getConnection(cid: string, id: string | null = null): any {
     if (Private.connection.has(cid)) {
       return Private.connection.get(cid);
     }
-    const obj = this._getLuminoWidgetFromShell(cid);
+    const obj = this._getLuminoWidgetFromShell(id || cid);
     IpylabModel.registerConnection(obj, cid);
     return obj;
   }