Q patch just recently landed to do that optimization for Option types containing a pointer. Options wrapping a value type still need an extra word however in order to distinguish between the Some/None cases though.
On Wednesday, May 29, 2013, Ziad Hatahet wrote: > Hi all, > > Does using Option incur a runtime cost (like increased memory usage) > compared to a hypothetical case if Rust had a NULL type in the language? Or > does it get optimized away, such that it is akin to using NULL in the first > place (albeit safer of course)? > > I have not looked at any assemblies, ut my intuition says that a > comparison with None is a single-word check, so it should be pretty fast. > > Thanks > > -- > Ziad >
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