We had a basic calculator running, but it had too much understanding of the interior functioning of the calculator.  We’ve changed this now, there is a UI base class from which user interfaces might derive.  This base class is given preformatted strings for things like stack contents and memory values, leaving the user interface code to concentrate solely on rendering those things it is told are there.  The user interface doesn’t have to know how the stack is laid out, or how to convert stack values to strings, that’s all handled in the internals in this new model.

We’ve defined generic functions on the ncurses class for three generic function definitions.  There’s an :after method on ui-set-active-mode, because the ncurses interface will modify its screen layout depending on what mode (interactive, programming, executing) is currently active.  We’ve also defined functions for ui-paint and ui-get-input, neither of which has an implementation for the base class.

We haven’t put everything together yet, because now the engine has to be rewritten to understand the new API.  Once that’s done, we’ll reassemble the calculator and test.

The current code is checked into the git repository under the tag v2014-12-03.