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Quick Start

Get from zero to a working debugging session in a few minutes.

1. Prerequisites

Before you begin, make sure Dapper is installed. See the Installation guide if you haven't done this yet.

2. Start the Debug Adapter

Open a terminal and launch the Dapper debug adapter:

python -m dapper.adapter --port 4711

The adapter will listen on port 4711 and wait for a client to connect. Keep this terminal open while you debug.

3. Configure VS Code

Create or open .vscode/launch.json in your project and add this configuration:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Dapper",
            "type": "python",
            "request": "attach",
            "debugServer": 4711
        }
    ]
}

This tells VS Code to attach to the running adapter rather than launching its own.

4. Set a Breakpoint

Open the Python file you want to debug in VS Code. Click in the left gutter next to a line of code to set a breakpoint (a red dot will appear).

5. Start Debugging

Press F5 or open the Run and Debug panel (Ctrl+Shift+D) and click Start Debugging. VS Code will connect to the Dapper adapter and run your program. Execution will pause at your breakpoint.

6. Inspect Variables

When execution is paused at a breakpoint:

  • The Variables panel (left sidebar) shows local and global variables in the current scope.
  • Hover over any variable in the editor to see its value in a tooltip.
  • Use the Debug Console (Ctrl+Shift+Y) to evaluate arbitrary expressions in the current frame.
  • Use the Call Stack panel to navigate between stack frames.

Next Steps