[haiku-development] Re: Launchbox 80 char limit fail
- From: John Scipione <jscipione@xxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Sat, 14 May 2011 15:06:27 -0400
>
> > I think one could remove the parenthesis and get the same result but I
> > wasn't sure if there is some sort of short circuiting behavior that was
> > being relied on here so I left the parens alone.
>
> How would the parens change the short circuit behavior? The ||
> operator is guaranteed left to right, even with parens.
Hike Danakian,
After writing a test program I now agree with you:
#include <stdio.h>
int main(void)
{
int i, j, k;
for (i = 0; i <= 1; i++) {
for (j = 0; j <= 1; j++) {
for (k = 0; k <= 1; k++) {
if (i || (j || k)) {
printf("case (i || (j || k)) i:%d, j:%d, k:%d,
result:true\n", i, j, k);
} else {
printf("case (i || (j || k)) i:%d, j:%d, k:%d,
result:false\n", i, j, k);
}
if (i || j || k) {
printf("case (i || j || k) i:%d, j:%d, k:%d,
result:true\n", i, j, k);
} else {
printf("case (i || j || k) i:%d, j:%d, k:%d,
result:false\n", i, j, k);
}
}
}
}
return 0;
}
Results:
$ ./test
case (i || (j || k)) i:0, j:0, k:0, result:false
case (i || j || k) i:0, j:0, k:0, result:false
case (i || (j || k)) i:0, j:0, k:1, result:true
case (i || j || k) i:0, j:0, k:1, result:true
case (i || (j || k)) i:0, j:1, k:0, result:true
case (i || j || k) i:0, j:1, k:0, result:true
case (i || (j || k)) i:0, j:1, k:1, result:true
case (i || j || k) i:0, j:1, k:1, result:true
case (i || (j || k)) i:1, j:0, k:0, result:true
case (i || j || k) i:1, j:0, k:0, result:true
case (i || (j || k)) i:1, j:0, k:1, result:true
case (i || j || k) i:1, j:0, k:1, result:true
case (i || (j || k)) i:1, j:1, k:0, result:true
case (i || j || k) i:1, j:1, k:0, result:true
case (i || (j || k)) i:1, j:1, k:1, result:true
case (i || j || k) i:1, j:1, k:1, result:true
Same result, so you are right, the parenthesis are superfluous.
With this confirmed I have refactored the patch to remove the unnecessary
parens. While doing so, I also collapsed the nested ifs into a single
if/else if block. Patch below:
--- src/apps/launchbox/LaunchButton.cpp
+++ src/apps/launchbox/LaunchButton.cpp
@@ -196,20 +196,18 @@ void
LaunchButton::MouseMoved(BPoint where, uint32 transit,
const BMessage* dragMessage)
{
- if ((dragMessage && (transit == B_ENTERED_VIEW || transit ==
B_INSIDE_VIEW))
- && ((dragMessage->what == B_SIMPLE_DATA
- || dragMessage->what == B_REFS_RECEIVED) || fRef)) {
- if (!fAnticipatingDrop) {
- fAnticipatingDrop = true;
- Invalidate();
- }
- }
- if (!dragMessage || (transit == B_EXITED_VIEW || transit ==
B_OUTSIDE_VIEW)) {
- if (fAnticipatingDrop) {
- fAnticipatingDrop = false;
- Invalidate();
- }
+ if (fAnticipatingDrop && (!dragMessage || transit == B_EXITED_VIEW
+ || transit == B_OUTSIDE_VIEW)) {
+ fAnticipatingDrop = false;
+ Invalidate();
+ } else if (!fAnticipatingDrop && ((dragMessage
+ && (transit == B_ENTERED_VIEW || transit == B_INSIDE_VIEW))
+ && (dragMessage->what == B_SIMPLE_DATA
+ || dragMessage->what == B_REFS_RECEIVED || fRef))) {
+ fAnticipatingDrop = true;
+ Invalidate();
}
+
// see if we should create a drag message
if (_HasFlags(STATE_TRACKING) && fRef) {
BPoint diff = where - fDragStart;
Thank you,
John Scipione
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