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Afraid To Fail

Couplers Responsibility Code SmellImplementation Smell Within Class

Every caller has to check whether things actually worked, because this code returns status codes instead of throwing exceptions. The defensive ifs cascade up the entire call chain.

3 min read 1 source

Overview

The Afraid To Fail is a Code Smell name inspired by the common fear (at least among students [1]) of failure, which is professionally called Atychiphobia [48] - being scared of failure.

I am referencing it here because the fear of admitting failure (that something went wrong) is a common, relatable, psychological trait, and facing that fear would benefit everyone. It is not a good idea to hope that maybe someone will get away with it. Undoubtedly, maybe even more often than not, that would be the case, but the more things stack up on that lack of honesty, the harder it will eventually hit if it ever gets discovered.

In programming, this behavior will clutter the code because, after a method or function call, additional code is required to check whether some status code is valid, a boolean flag is marked, or the returned value is not None. And all of that is outside of the method scope.

If it is expected that a method might fail, then it should fail, either by throwing an Exception or, if not - it should return a special case None/Null type object of the desired class (following the Null Object Pattern), not null itself. For example, if an expected object cannot be received or created, and instead of some status indicator is sent back (which has to be checked after the method is completed), the smells it generates would be Afraid to Fail as well as Teardown Code Code Smell. Instead, following the Fail Fast Principle, the code should throw an error.

Problems

🗑
Code Pollution

Require additional if checks for return status or null checks.

🔗
Coupling

Creates artificial coupling with the method caller.

⚖
Fail Fast Violation

In system design, the Fail Fast concept is about reporting immediately when any condition is likely to indicate failure.

Violated Patterns
Null Object

Example

Returning Status Code, which has to be checked eventually whether it succeeded
1def create_foo() -> dict:
2    response = requests.get('https://api.github.com/events')
3    if response.status_code != requests.codes.ok:
4        return {'status_code': response.status_code, 'foo': None}
5    return {
6        'status_code': response.status_code,
7        'foo': Foo(**response.json())
8    }
9
10foo_response: dict = create_foo()
11if foo['status_code'] != requests.codes.ok:
12    foo: Foo = foo_response['foo']
13...
PYTHON

Refactoring

  • Move Method

Sources

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