On Mon, Nov 28, 2011 at 1:38 PM, David Kilzer <ddkil...@webkit.org> wrote:
> In a discussion on Bug 71921<https://bugs.webkit.org/show_bug.cgi?id=71921>, > Antti, Darin Adler and I started a discussion about using C++ constant > pointers in WebKit. Does the WebKit community have a consensus opinion on > the matter? > > * Pros > - Documents use of variable. > - Prevents misuse of variable in a later patch (by a different author) > through enforcement of pointer const-ness. > - May help compiler optimize code. (We weren't sure whether modern > compilers do this on their own or not.) > Don't think so. As far as I know, C++ compilers ignore "const" for the purpose of code optimization because we can always re-cast it to non-const variable. On the other hand, modern optimizing compilers might do SSA-based constant<http://en.wikipedia.org/wiki/Sparse_conditional_constant_propagation> propagation <http://gcc.gnu.org/news/ssa-ccp.html> regardless of constness of a variable. * Cons > - Darin Adler doesn't ever recall fixing a bug in WebKit where a > constant pointer would have helped. > - Slightly more verbose syntax for constant pointers to a constant > string (const char * const pointer;) or even a constant pointer to a > mutable string (char * const pointer;). > I'd argue against using constant pointers simply because I don't think the existing WebKit code uses it, and I don't see much benefit in comparison to pointers or references to const objects. - Ryosuke
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