2.7 Avoiding a potential problem with break statements

The common way to understand a for statement is that it creates a for all condition. At the end of the statement, we can assert that, for all items in a collection, the processing in the body of the statement has been done.

This isn’t the only meaning a for statement can have. When the break statement is used inside the body of a for statement, it changes the semantics to there exists. When the break statement leaves the for (or while) statement, we can assert there exists at least one item that caused the enclosing statement to end.

There’s a side issue here. What if the for statement ends without executing the break statement? Either way, we’re at the statement after the for statement. The condition that’s true upon leaving a for or while statement with a break statement can be ambiguous. We can’t easily tell; this recipe gives some design guidance.

The problem...