On 3/30/20 5:17 PM, Pham wrote:
On Monday, 30 March 2020 at 18:20:00 UTC, Steven Schveighoffer wrote:
I don't really understand the question about "nothrow".
void main()
{
static class Foo { int i; }
static bool checkFoo() nothrow
{
// error when compile
//return typeid(Foo) == Foo.classinfo;
// ok when compile
return typeid(Foo) is Foo.classinfo;
}
checkFoo();
}
In this case, the difference is == vs. `is`, not classinfo vs typeid:
typeid(Foo) == typeid(Foo); // throws
Foo.classinfo == Foo.classinfo; // throws
typeid(Foo) is typeid(Foo); // nothrow
Foo.classinfo is Foo.classinfo; // nothrow
`is` between class instances means "is this the same instance". It is a
simple comparison of two pointers basically.
== between classes means calling object.opEquals [1], which is not
nothrow (or nogc, or pure).
In fact, they should be the same instance, because typeid and classinfo
do the same thing.
-Steve
[1] https://dlang.org/phobos/object.html#.opEquals
