Re: Coding style question - Mailing list pgsql-hackers

Shouldn't we turn on warnings by the compiler on uninitialized
variables? This can also be helpful.

--Imad
www.EnterpriseDB.com


On 11/2/06, korryd@enterprisedb.com <korryd@enterprisedb.com> wrote:
>
>  I've noticed a trend in the PostgreSQL code base - for some reason, we tend
> to avoid initializing automatic variables (actually, the code base is pretty
> mixed on this point).
>
>  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