Set up VSCode to Debug Python in Maya

In the previous series of articles, we built a quasi auto-attach workflow to debug 3ds Max's Python scripts with VSCode. Fortunately, that workflow was general enough that trying to apply that to Maya only requires some slight tweaking.

`bootstrap.mel`

The Maya command line interface does not expose any way to execute a Python script. However, it does accept Mel Scripts and we can easily create a bootstrap.mel instead. Since our goal is to keep the work centralized in the bootstrap.py script, the resulting MEL script simply executes that file:

// Execute the Python bootstrap script
string $python_env = getenv("PROJECT_MAYA_PYTHON_SCRIPT");
string $python_files[] = stringToStringArray($python_env, ";");
for( $python_file in $python_files )
{
    string $filename = fromNativePath($python_file);
    print("Executing " + $filename + " python file\n");
    python("exec(open('" + $filename + "').read())");
}

We follow the same model as before and use environment variables to pass parameters into the process. We use the new PROJECT_MAYA_PYTHON_SCRIPT environment variable to contain a list of ; separated python files that the MEL script will execute using MEL script's python command.

Updated Launcher

We need to update the launcher.json file in VSCode to account for the new executable, command line, and our environment variable:

{
    "name": "Maya 2018",
    "type": "cppvsdbg",
    "request": "launch",
    "program": "${env:ProgramW6432}\\Autodesk\\Maya2018\\bin\\maya.exe",
    "args": [
        "-script",
        "${workspaceFolder}\\scripts\\bootstrap.mel"
    ],
    "stopAtEntry": false,
    "cwd": "",
    "environment": [
        // PROJECT_SCRIPTS contains a `;` separated list of filenames to run at startup in `bootstrap.py`
        {
            "name": "PROJECT_SCRIPTS",
            "value": "${workspaceRoot}\\.env27\\Scripts\\activate_this.py"
        },
        // PROJECT_DEBUG_PORT / PROJECT_DEBUG_HOST should match 'Remote Attach' below.
        {
            "name": "PROJECT_DEBUG_PORT",
            "value": "5678"
        },
        {
            "name": "PROJECT_DEBUG_HOST",
            "value": "localhost"
        },
        // PROJECT_LOG_LEVEL for the level of `logging` statements
        {
            "name": "PROJECT_LOG_LEVEL",
            "value": "DEBUG"
        },
        // PROJECT_MAYA_PYTHON_SCRIPT contains a `;` separated list of filenames to run at startup in `bootstrap.mel`
        {
            "name": "PROJECT_MAYA_PYTHON_SCRIPT",
            "value": "${workspaceFolder}\\scripts\\bootstrap.py"
        }
    ]
}

And we still need to add the compound job that launches this new companion launch configuration with the generic Python: Remote Attach auto-attach configuration from the previous article:

{
    "name": "Python Maya 2018",
    "configurations": [
        "Maya 2018",
        "Python: Remote Attach"
    ]
}

We're still following the same workflow from our previous 3ds Max example. The only real difference with Maya is the addition of a bootstrap.mel, which is only needed as a workaround to Maya's command line interface.