summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--Documentation/CodingGuidelines27
1 files changed, 27 insertions, 0 deletions
diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index aeaa82451e..02ca67c4ca 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -222,6 +222,33 @@ For C programs:
- Double negation is often harder to understand than no negation
at all.
+ - There are two schools of thought when it comes to comparison,
+ especially inside a loop. Some people prefer to have the less stable
+ value on the left hand side and the more stable value on the right hand
+ side, e.g. if you have a loop that counts variable i down to the
+ lower bound,
+
+ while (i > lower_bound) {
+ do something;
+ i--;
+ }
+
+ Other people prefer to have the textual order of values match the
+ actual order of values in their comparison, so that they can
+ mentally draw a number line from left to right and place these
+ values in order, i.e.
+
+ while (lower_bound < i) {
+ do something;
+ i--;
+ }
+
+ Both are valid, and we use both. However, the more "stable" the
+ stable side becomes, the more we tend to prefer the former
+ (comparison with a constant, "i > 0", is an extreme example).
+ Just do not mix styles in the same part of the code and mimic
+ existing styles in the neighbourhood.
+
- Some clever tricks, like using the !! operator with arithmetic
constructs, can be extremely confusing to others. Avoid them,
unless there is a compelling reason to use them.