Merge pull request #93 from brichet/debugger_info_copy_to_globals

JEP for copy-to-globals support in debugger_info

Author: JohanMabille

debugger-info-copy-to-globals/debugger-info-copy-to-globals.md

@@ -0,0 +1,69 @@
+---
+title: Debugger support to copyToGlobals
+authors: Nicolas Brichet (@brichet)
+issue-number: xxx
+pr-number: xxx
+date-started: 2023-02-20
+---
+
+# Summary
+
+This JEP introduces a new field to the kernel debugger_info response. This new
+field will inform the UI that the debugger supports the `copyToGlobals` request.
+
+# Motivation
+
+The `copyToGlobals` request has been introduced in
+[ipykernel](https://github.com/ipython/ipykernel/pull/1055) and in
+[xeus-python](https://github.com/jupyter-xeus/xeus-python/pull/562) to copy a local
+variable to the global scope during a breakpoint. It would be useful to inform the
+UI if this is supported by the kernel before displaying the corresponding menu entry.
+
+# Proposed Enhancement
+
+We propose to add a new `copyToGlobals` boolean field to the `debugger_info`
+response which will inform the UI that this request is supported.
+
+## Reference-level explanation
+
+This boolean flag should be included in the `debugger_info` response from the kernel
+which supports the feature. It is optional, assuming that its absence is understood
+as `false` from the client perspective.
+
+If the feature is supported, the kernel must provide a function for copying a variable
+from a local scope to the global scope.
+The communication between the UI and the kernel (request - response) will have the
+structures described at
+https://jupyter-client.readthedocs.io/en/latest/messaging.html#copytoglobals.
+
+- Request (from UI to kernel)
+
+  ```python
+  {
+    'type': 'request',
+    'command': 'copyToGlobals',
+    'arguments': {
+      # the variable to copy from the frame corresponding to `srcFrameId`
+      'srcVariableName': str,
+      'srcFrameId': int,
+      # the copied variable name in the global scope
+      'dstVariableName': str
+    }
+  }
+  ```
+
+- Response (from kernel to UI)
+
+  ```python
+  {
+    'type': 'response',
+    'success': bool,
+    'command': 'setExpression',
+    'body': {
+      # string representation of the copied variable
+      'value': str,
+      # type of the copied variable
+      'type': str,
+      'variablesReference': int
+    }
+  }