Good programmers manage side effects. They have an idea of what kind of side effects a particular coding strategy or pattern is going to tend to produce. They u

Good programmers manage side effects. They have an idea of what kind of side effects a particular coding strategy or pattern is going to tend to produce. They understand the range of bugs they are likely to encounter with an implementation and shore them up quickly. Likewise, they also tend to produce more desirable side effects - things that maybe weren't described in the spec but are a noticeable improvement (e.g., responsive UI behavior)