Useful Programming Trick .. But 40 years late!

[ttw]

The only time I did something similar was in writing a text editor in Fortran. Depending on context, each incoming keystroke may go arbitrary places (insert mode, delete mode, overwrite mode, macro create, etc.)

The main point was that one could use Structured Programming (supposedly to make programs easy to read) and still write arbitrary branching programs.

During Structured Programming's heyday, it was difficult to write some numeric algorithms because iterations may have multiple termination conditions (convergence or iteration limit is a common double condition).