The Mailbox Html Formatter

Separation of Concerns

One question that may have come up while working on the mailbox text formatter exercise is:

Why would we have a separate class for formatting the ASCII table (that is, a plain text table that uses characters like +, -, and |)?

The reason is: We want each one of our classes to encapsulate one concept that is useful in our application. We also say: each one of our classes should be concerned with one responsibility.

An email vaguely resembles the concept of an analog letter, written on paper: some message is being sent from one person to another. Nowadays everyone knows what an email is: it stores all the information about this particular message. The same is true for mailboxes, which ...