Code Quality Improvement - Session 54: Silence Can Be Golden

When implementing mapSuccess or flatMap in the ApiResult model that represents API call results, there are cases where @file:Suppress("warnings") is used across an entire file to avoid unchecked cast warnings that occur during type casting. However, this also hides important warnings that may arise in the future (e.g., the use of deprecated functions due to a library update), creating a high risk of missing bugs.

When a warning occurs, you should respond according to the following priorities.

1. Resolve the cause of the warning: Whenever possible, it is best to resolve the warning rather than suppress it. For example, you can use Kotlin's out keyword to make a type parameter covariant, or adjust the type parameter of the Failed class to solve the problem without a downcast.

2. Limit the suppression scope and method: Only consider suppression when the cause cannot be resolved (such as dependencies on external libraries), and in that case, follow these principles.

• Limit the scope: Narrow the suppression scope to a class, function, or specific statement rather than the entire file.
• Specify the type: Instead of turning off all warnings like warnings, specify only the particular warning type, such as UNCHECKED_CAST.
• State the reason: Clearly explain in a comment why this warning must be suppressed.