PyCharm-like Evaluate Expression

A VS Code / Cursor extension that provides a multi-line Evaluate Expression panel for debugging, inspired by PyCharm's Evaluate Expression dialog.

Why This Extension?

VS Code's Debug Console only supports single-line expressions. If you're coming from PyCharm, you know how powerful it is to evaluate multi-line code blocks — loops, conditionals, function calls — all at once while paused at a breakpoint. This extension brings that workflow to VS Code and Cursor.

Screenshot

Tip: For the best experience, detach the panel into a floating window (see Floating Window below).

Features

• Syntax-highlighted code editor — CodeMirror 6 with Python/JavaScript highlighting, line numbers, auto-indent, and bracket matching
• Multi-line code editor — evaluate many lines at once, not just single expressions
• Statement mode — automatically wraps code in a function so return, loops, and multi-line logic work
• Expression mode — evaluate a single expression as-is
• Multi-language support — Python, JavaScript/TypeScript (Node.js, Chrome), and generic DAP debuggers; CodeMirror language mode switches automatically
• CodeLens integration — "Evaluate Selection" and "Add to Watches" links appear above selected code during debugging
• Watches — add expressions to a watch list that auto-refreshes when the debugger stops
• History — navigate through previous evaluations with Alt+Up/Down
• Right-click context menu — select code, right-click → "Evaluate: Run Selection" during debugging
• Persistent preferences — remembers your last mode (Statements/Expression) and code between sessions
• Debug logging — built-in diagnostic log for easy bug reporting

Usage

1. Start a debug session and pause at a breakpoint
2. Open the Evaluate panel: Ctrl+Alt+E (or Command Palette → "Evaluate: Open Panel")
3. Type multi-line code in the editor
4. Click Evaluate (or press Ctrl+Enter)
5. See the result in the output area

Tip: Floating Window

For the best experience, detach the Evaluate panel into its own window:

1. Right-click the "Evaluate Expression" tab
2. Select "Move into New Window"

This mimics PyCharm's floating Evaluate dialog and lets you keep your code fully visible while evaluating expressions. You can position it on a second monitor or anywhere on your screen.

Keybindings

Note: If Ctrl+Alt+E doesn't work in your environment (e.g., Remote-SSH sessions), use the fallback Ctrl+Shift+F8 or open via Command Palette → "Evaluate: Open Panel". You can also customize keybindings in File → Preferences → Keyboard Shortcuts.

Context Menu

When paused at a breakpoint, select code in the editor and right-click to see:

• Evaluate: Run Selection — sends the selected code to the Evaluate panel
• Evaluate: Add Selection to Watches — adds the selected expression to the watch list

Scoping Note

In Statements mode, code is wrapped in a function for execution. This means:

• Mutations to existing objects (e.g., self.next = None) work as expected
• New local variables created inside the snippet do NOT persist in the paused frame

Known Limitations

• Variables panel does not auto-refresh after evaluating statements that mutate objects. VS Code does not expose an API for extensions to force-refresh the Variables panel without advancing execution. Workaround: after mutating a variable via the Evaluate panel, either step once (F10/F11) or type the variable name in the Debug Console to see the updated value.

Bug Reporting

If you encounter an issue:

1. Enable verbose logging: Settings → evaluate.verboseLogging → true
2. Reproduce the issue
3. Copy the log: Ctrl+Shift+P → "Evaluate: Copy Debug Log to Clipboard"
4. Paste into a GitHub issue

The log includes extension version, VS Code version, OS, and detailed DAP communication.

Development

npm install
npm run compile
# Press F5 in VS Code/Cursor to launch the Extension Development Host

Requirements

• VS Code 1.85+ or Cursor
• A debug adapter that supports the DAP evaluate request (e.g., Python + debugpy)

Changelog

v1.3.0

• New: Syntax-highlighted code editor powered by CodeMirror 6 (Python highlighting, line numbers, auto-indent, bracket matching)
• New: Multi-language support — JavaScript/TypeScript wrapping (IIFE) for Node.js/Chrome debuggers; language auto-detection from debug session type
• New: CodeLens integration — "Evaluate Selection" and "Add to Watches" links appear inline above selected code during debugging (configurable via evaluate.showCodeLens)
• New: CodeMirror language mode switches automatically to match the active debugger (Python, JavaScript/TypeScript)
• Fix: IndentationError on multi-line statements in Statements mode (whitespace normalization and auto-dedent)
• Fix: Over-indented code from "Evaluate Selection" now correctly dedented (tab normalization)
• Fix: return injection no longer breaks indentation when last line is inside a nested block (e.g. for/if/while)

v1.1.0

• Fix: Added fallback keybindings (Ctrl+Shift+F8, Ctrl+Shift+F9) for Remote-SSH compatibility
• Fix: Selected code from editor is now auto-dedented before evaluation
• New: Right-click context menu for "Evaluate: Run Selection" and "Add to Watches" during debugging
• New: Panel remembers last used mode (Statements/Expression) and code input between sessions
• Improved: Comprehensive README with badges, keybinding table, floating window tip, and bug reporting guide

v1.0.2

• Added calculator-style extension icon

v1.0.1

• Added VS Code Output Channel for user-visible debug logging
• Added evaluate.verboseLogging setting
• Added "Evaluate: Copy Debug Log to Clipboard" command
• Added environment info (version, OS) to log header
• Error notifications now include a "Show Log" button

v1.0.0

• Initial release: multi-line Evaluate Expression panel
• Statements and Expression modes
• Watch expressions with auto-refresh
• History navigation
• DAP-based evaluation (Python/debugpy primary target)

License

MIT