>> if (ch == t.c_cc[VINTR]) {
>> } else {
>> if (ch == t.c_cc[VQUIT]) {
>> } else {
>> if (ch == t.c_cc[VKILL]) {
>> } else {
>> }
>> }
>> }
> For this, I would prefer
> if (ch == t.c_cc[VINTR]) {
> } else if (ch == t.c_cc[VQUIT]) {
> } else if (ch == t.c_cc[VKILL]) {
> } else {
> }
Sure. So would I. But that involves a subordinate clause (each if
except the first) that isn't brace-bracketed. Note what I wrote before
the example: "[s]lavishly always adding [braces] makes [...]"; that was
an example of readability impairment resulting from insistence on
always brace-surrounding dependent statements under all circumstances.
> In this case, perhaps even a switch might better,
Except that can't be done as a switch, because the cases aren't
compile-time constant expressions. The comment before it in the
original even calls it out as such:
/*
* Scan for special characters. This code
* is really just a big case statement with
* non-constant cases. [...]
*/
(sys/kern/tty.c, at least as of 1.227.4.2 - I simplified the code
significantly to not distract from my point).
> switch (ch) {
> case t.c_cc[VINTR]) {
> ...do INTR processing...
> break;
> };
> [...]
That is definitely not C. The syntax is wrong (it looks like a C
switch but with sh-style ) terminators on the cases) and the cases are
non-constant. I chose that example specifically because it can't be
transformed into a (C) switch; it was the first example to come to mind
of a relatively unavoidable else-if chain in live code. (My memory was
flaky; see below.)
That particular one can be transformed so it doesn't walk into the
right margin even if you _do_ insist on brace-bracketing, but it calls
for a different trick. The first way that comes to mind is
do {
if (ch == t.c_cc[VINTR]) {
...do INTR processing...
break;
}
if (ch == t.c_cc[VQUIT]) {
...do QUIT processing...
break;
}
if (ch == t.c_cc[VKILL]) {
...do KILL processing...
break;
}
...etc...
} while (0);
Is that better? Sometimes, maybe. tty.c uses gotos; in the simplified
form we've been discussing, that would be
if (ch == t.c_cc[VINTR]) {
...do INTR processing...
goto endcase;
}
if (ch == t.c_cc[VQUIT]) {
...do QUIT processing...
goto endcase;
}
if (ch == t.c_cc[VKILL]) {
...do KILL processing...
goto endcase;
}
...
endcase:
but that's pretty close to the bottom of my own preference list.
Amusingly, the original of the example I cited isn't actually an
example of what I was trying to cite at all. Perhaps I should have
made up something plausible but entirely fictitious, or gone and dug up
an example of a long else-if chain in real code somewhere.
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