On 3/30/20 1:06 PM, Pham wrote:
On Monday, 30 March 2020 at 15:15:08 UTC, Steven Schveighoffer wrote:
They are both the same. Historically they were different (ClassInfo
was its own type different from TypeInfo_Class). I would recommend
typeid for future-proof code (it's possible, however unlikely, that
.classinfo at some point goes away).
Will it be the same if using "is", the reason is for function that use
"nothrow" attribute?
if (cc.classinfo is typeid(CC))
It should be identical.
For fun I did an AST dump for this code:
void main()
{
Object o;
auto ti = typeid(o);
auto ci = o.classinfo;
}
And this is what I get:
void main()
{
Object o = null;
TypeInfo_Class ti = typeid(o);
TypeInfo_Class ci = **o;
return 0;
}
So it looks like typeid(o) is not lowered to something, but o.classinfo
is lowered to **o (the first field in an object is the TypeInfo).
I would say that this is going to reduce to the same thing in both
cases, but I find it interesting that the AST is different.
I don't really understand the question about "nothrow".
-Steve
