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How to Solve the "Unreachable Code" Warning in Python

The unreachable code warning in Python indicates that a section of your code will never be executed. This can result from misplaced return or raise statements, infinite loops, or conditions that are always true.

This guide explores the common causes of this warning and provides solutions to eliminate them, ensuring your code is efficient and error-free.

Understanding the Cause: return Statements​

The most common reason for unreachable code is a return statement that prematurely exits a function. Code placed after the return will never be executed:

def example():
    a = 123
    return 'tutorialreference.com'
    b = 456  # Unreachable code
example()

Solution: Move variable declarations and other essential code before the return statement.

Understanding the Cause: raise Statements​

Similar to return, a raise statement that throws an exception will also prevent any subsequent code from running.

def example():
    a = 123
    raise ValueError('invalid value')
    print('This will not execute') # Unreachable code
example()

Solution: Ensure any necessary cleanup or handling code is placed within a try/except block before the raise statement.

Incorrect Indentation​

Incorrect indentation can lead to code being mistakenly placed inside a function, loop, or conditional block, rendering it unreachable:

def example():
    a = 123
    return 'tutorialreference.com'

b = 456 # Incorrect indent - outside the function body
print(b)
example()

Solution: Ensure code is properly indented according to its intended scope. Outdent code to move it out of a function body.

Conditions That Are Always True​

Unreachable code can also result from an if condition that always evaluates to True.

def example():
    a = 123

    if 10 > 0:
        return 'tutorialreference.com'
    b = 456  # Unreachable code
example()

Solution: Review the code for impossible conditions in if statements, and remove or adjust the logic appropriately.

Resolving the Warning in VS Code (Pylance)​

Sometimes, the unreachable code warning in Visual Studio Code (using the Pylance extension) can be a false positive.

Disabling editor.showUnused​

You can disable the specific warning by disabling the editor.showUnused setting:

  1. Press Ctrl + Shift + P (or Cmd + Shift + P on macOS) to open the Command Palette.
  2. Type user settings json.
  3. Click on Preferences: Open User Settings (JSON).
  4. Add the following to your settings.json file:
"[python]": {
"editor.showUnused": false
}

Settings in .vscode/settings.json​

You can also apply this setting to the current project only by creating a .vscode folder in the project root and adding a settings.json file:

// .vscode/settings.json
{
    "[python]": {
    "editor.showUnused": false
    }
}
  • With this approach, you will only disable this warning in a specific project, not globally.

Restarting Your IDE​

If the warning persists after correcting the code and adjusting settings, try restarting your code editor (Visual Studio Code, PyCharm, etc.). This can sometimes resolve issues with stale warnings.

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