Sunday, January 24, 2010

Is this code broken?

[This was originally posted at]

What constitutes broken code? Everyone agrees that code that crashes in production and threatens to have developers fired is indeed broken. But where's the line? Is the following code broken:

  • The code logs incorrect data in an error log file?
  • The code displays incorrect values in a label (like a mis-formatted date)?
  • If a certain rare case occurs (like a button is pressed at exactly 12:00AM, or an uploaded file size is exactly 1.00 MB), then the code crashes?
  • The code has mis-leading names for variables and methods. For example, it has a method "IsNumber" that checks only for integers, or "IsLetter" that allows for special characters? Say the current program calls the method with correct data so that the app never crashes?

In all these cases, say the application essentially "works" and handles the main use cases.

The problem is maintenance. Maintaining and extending code is an expensive part of the total cost of ownership. You could spend hours tracking down a single erroneous line of code. Code that is low quality (tons of copy & paste, misnamed methods, misleading logic, etc...) is going to be a fortune to maintain. On the other hand, certain functional errors that have zero impact on the business can perhaps be documented as "known-issues" (i.e. the month is formatted in a label with a preceding zero like "03" instead of just "3".

I'd say it comes down to the business, and the code is broken if it costs the business more than it should - whether it be via maintenance costs or functional errors that hinder the end users. Perhaps the question isn't as much "is this code broken", but "how can we maximize the business-value of this code?"

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