This is a template for anyone to design and build their own calculator. It is very modular and all the code except the number printing is trivial. Draw your own skin in any tool, then link the buttons to the code by simply drawing a black rectangle over each button as the skin for that button. Start by dragging the existing buttons into place as a rough guide. This is a reverse polish calculator with a explicit push-down stack. The stack is visible in this demo although you may remove it if you need space for more buttons. To create a new function, duplicate an appropriately similar one (eg '-' for a binary operator, or 'int' for a unary operator) and modify the logic accordingly. You can build a very powerful custom calculator, quickly, with this framework. Currently I am still developing the code and there are two known bugs in the tricky area of number display: negative numbers and decimal parts are broken, and display of large numbers > 10^9 are not implemented. Otherwise the code that is finished is extremely robust. (There's also one 'To Do' - parameterise the size and position of the numeric display. It currently is positioned for a previous skin I was using.)
