it's sometimes useful to emulate dynamic casting in runtime having only TypeInfo_Class at hands. now one has to rely on undocumented (and unexported) `_d_dynamic_cast()` and friends, writing something like this: // get druntime cast function private extern(C) void* _d_dynamic_cast (Object o, ClassInfo c); bool isCastable (Object O, TypeInfo_Class ti) { return (_d_dynamic_cast(o, ti) !is null); } it would be fine to introduce and use a documented API for that, like this: ti.dynamicCast(O) ti.isBaseOf(O) i.e. we should add these methods to TypeInfo_Class. also, the same methods should be added to TypeInfo_Interface.
p.s. `ti.dynamicCast(O)` should still return `void*`. not a big deal, it's very internal API anyway.
sample patch: diff --git a/src/object.d b/src/object.d index 097fc5a..6eb9163 100644 --- a/src/object.d +++ b/src/object.d @@ -21,6 +21,8 @@ private { extern (C) Object _d_newclass(const TypeInfo_Class ci); extern (C) void rt_finalize(void *data, bool det=true); + extern (C) void* _d_dynamic_cast(Object o, ClassInfo c); + extern (C) int _d_isbaseof(ClassInfo oc, ClassInfo c); } // NOTE: For some reason, this declaration method doesn't work @@ -860,6 +862,17 @@ unittest */ class TypeInfo_Class : TypeInfo { + final void* dynamicCast (Object o) + { + return (o !is null ? _d_dynamic_cast(o, this) : null); + } + + // is this typeinfo base of `o`? + final bool baseOf (Object o) + { + return (o !is null ? (_d_isbaseof(typeid(o), this) != 0) : false); + } + override string toString() const { return info.name; } override bool opEquals(Object o)
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