For example in _bt_check_unique() we have:
static TransactionId
_bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
Buffer buf, ScanKey itup_scankey)
{
TupleDesc itupdesc = RelationGetDescr(rel);
int natts = rel->rd_rel->relnatts;
OffsetNumber offset,
maxoff;
Page page;
BTPageOpaque opaque;
Buffer nbuf = InvalidBuffer;
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
maxoff = PageGetMaxOffsetNumber(page);
offset = _bt_binsrch(rel, buf, natts, itup_scankey, false);
...
Notice that four variables are not initialized; instead we assign values to them immediately after declaring them.
I would probably write that as:
static TransactionId
_bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
Buffer buf, ScanKey itup_scankey)
{
TupleDesc itupdesc = RelationGetDescr(rel);
int natts = rel->rd_rel->relnatts;
Page page = BufferGetPage(buf);
OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
OffsetNumber offset = _bt_binsrch(rel, buf, natts, itup_scankey, false);
Buffer nbuf = InvalidBuffer;
...
I'm not trying to be pedantic (it just comes naturally), but is there some reason that the first form would be better? I know that there is no difference in the resulting code, so this is purely a style/maintainability question.
I guess the first form let's you intersperse comments (which is good).
On the other hand, the second form makes it easy to see which variables are un-initialized. The second form also prevents you from adding any code between declaring the variable and assigning a value to it (which is good in complicated code; you might introduce a reference to an unitialized variable).
Just curious.
-- Korry
