E731 do not assign a lambda expression, use a def

Understanding named function advantages

When dealing with def, you are dealing with a named function that trumps a variable-assigned lambda in multiple ways:

• Error tracebacks in named functions include the function's name, simplifying the debugging process.
• Named functions come with docstrings, providing a handy documentation guideline to their usage and purpose.
• String representations of a named function prove more informative, thus making logging and exception reporting more insightful.

Lambda: When and Where?

Lambda expressions excel in scenarios requiring an elegant, unnamed function without the formality of establishing a named function:

• As arguments to functional paradigms like map(), filter(), and sorted().
• Within list, set, or dictionary comprehensions for pithy transformation flows.
• To craft simple callback functions within framework-centric constructs like GUI applications.

Guarding against lambda misuse

Misuse of the lambda function can cloud your code's readability and tangle its semblance of complexity:

• If the lambda expression begins to groan under complexity, replace it with a named function.
• Avoid deeper nesting of lambda expressions; it can render your code challenging to follow and comprehend.
• Shy away from assigning a lambda to a name – remember, 'lambda' in Greek means 'anonymous'.

Integrating clarity with conciseness

Occasionally, you might yearn to maintain code compactness while steering clear of the drawbacks of lambda assignment:

• Invoke lambda internally within functions where a temporary local function seems overbearing.
• Inject lambda expressions for simple one-shot operations – especially if they accentuate your code's expressiveness.
• Resort to def functions when you foresee expansion or reuse of the operation.

Resisting lambda temptation

Despite its lure, the use of lambda can often lead to obscurity and confusion. Let's recount a few instances where resolute denial proves beneficial:

• It's tempting to use lambdas for class properties or simple methods, but def statements serve the purpose just as well, if not better.
• If your class internals begin to get complex, consider using private functions (def _private_method) instead of resorting to lambdas.

Abiding by guiding principles

Maintaining a delicate balance between PEP 8 adherence and readability is key:

• Clarity overrides the style guide; do not let the fear of transgressing PEP 8 impede your code clarity.
• Primary principles such as DRY (Don't Repeat Yourself) can warrant a thoughtful deviation from this rule.
• Always stay tuned for any modifications to PEP 8 or community norms that could redefine the permissible boundaries of such practices.