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| author | Ken Raeburn | 2015-11-01 01:42:21 -0400 |
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| committer | Ken Raeburn | 2015-11-01 01:42:21 -0400 |
| commit | 39372e1a1032521be74575bb06f95a3898fbae30 (patch) | |
| tree | 754bd242a23d2358ea116126fcb0a629947bd9ec /admin/notes/iftc | |
| parent | 6a3121904d76e3b2f63007341d48c5c1af55de80 (diff) | |
| parent | e11aaee266da52937a3a031cb108fe13f68958c3 (diff) | |
| download | emacs-39372e1a1032521be74575bb06f95a3898fbae30.tar.gz emacs-39372e1a1032521be74575bb06f95a3898fbae30.zip | |
merge from trunk
Diffstat (limited to 'admin/notes/iftc')
| -rw-r--r-- | admin/notes/iftc | 26 |
1 files changed, 0 insertions, 26 deletions
diff --git a/admin/notes/iftc b/admin/notes/iftc deleted file mode 100644 index 983b1486685..00000000000 --- a/admin/notes/iftc +++ /dev/null | |||
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| 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 | |||