| 1 | Iso-Functional Type Contour |
| 2 | |
| 3 | |
| 4 | This is a term coined to describe "column int->float" change approach, and can |
| 5 | be used whenever low-level types need to change (hopefully not often!) but the |
| 6 | meanings of the values (whose type has changed) do not. |
| 7 | |
| 8 | The premise is that changing a low-level type potentially means lots of code |
| 9 | needs to be changed as well, and the question is how to do this incrementally, |
| 10 | which is the preferred way to change things. |
| 11 | |
| 12 | Say LOW and HIGH are C functions: |
| 13 | |
| 14 | int LOW (void) { return 1; } |
| 15 | void HIGH (void) { int value = LOW (); } |
| 16 | |
| 17 | We want to convert LOW to return float, so we cast HIGH usage: |
| 18 | |
| 19 | float LOW (void) { return 1.0; } |
| 20 | void HIGH (void) { int value = (int) LOW (); } /* iftc */ |
| 21 | |
| 22 | The comment /* iftc */ is used to mark this type of casting to differentiate |
| 23 | it from other casting. We commit the changes and can now go about modifying |
| 24 | LOW and HIGH separately. When HIGH is ready to handle the type change, the |
| 25 | cast can be removed. |
| 26 | |
| 27 | ;;; arch-tag: 3309cc41-5d59-421b-b7be-c94b04083bb5 |