On Tue, Jan 5, 2021 at 3:05 AM Ron Prestenback <ronprestenb...@gmail.com> wrote: > > Since I'm very new to V8 and might be using the wrong terminology, I'll just > explain what I'm trying to do :) > > I am using V8 embedded (within UnrealJS / UE4). At startup, it iterates > through UClasses (UE4 class objects) and creates a FunctionTemplate for each > one. It iterates the class's functions, creating a FunctionTemplate for each > one, and adds that FunctionTemplate to the owning class's FunctionTemplate > via "OwnerClassTemplate->PrototypeTemplate()->Set(function_name, > function_template)". The idea is to make it so that in javascript, you can > call UE4 functions the same way you'd call them in UE4 C++, more or less. > > But something goes wrong around UClass 270 or so. I trigger an assert in V8 > when calling GetFunction() on the function template for a class. > > <unknown>:-1: Uncaught TypeError: Object template has duplicate property > 'ExecuteUbergraph' > > (ExecuteUbergraph is a function in the overall base class of UE4 - UObject) > > On the surface, it seems like this should be impossible so I want to log out > the properties of each of these FunctionTemplate objects to see what's been > added to each one. But I can't figure out how to do this. > > I've tried a bunch of things to convert this FunctionTemplate into an object, > based on the understanding that a FunctionTemplate is really a > FunctionTemplateInfo object (that I retrieve via Utils::OpenHandle) and > FunctionTemplateInfo is where those properties would be. > FunctionTemplateInfo appears to ultimately derive from Object > (FunctionTemplateInfo -> TemplateInfo -> Struct -> HeapObject -> Object), so > it seemed reasonable to try to convert the FunctionTemplate to an object, and > call GetOwnPropertyNames on it. But I'm not having any success with this > approach, so I must be doing something wrong. I can successfully convert the > FunctionTemplate handle into a normal Object handle, but it triggers asserts > when I try to use it, suggesting that my conversion (which involved some > reinterpret_casting) is not valid. > > My FunctionTemplate::ToObject function basically amounts to: > i::Handle<i::FunctionTemplateInfo> self = Utils::OpenHandle(this); > Local<v8::Object> Result = Utils::Convert<i::FunctionTemplateInfo, > v8::Object>(self); > return Result; > > > Is there a way to iterate the properties of a FunctionTemplate / > ObjectTemplate? What concept have I horribly misunderstood here? :)
I can understand where your confusion comes from because V8's internal vocabulary is a little ambiguous here. :-) A v8::FunctionTemplate is a heap object but it's not a JS object: - v8::Object = JSObject -> JSReceiver -> HeapObject -> Object - v8::FunctionTemplate = FunctionTemplateInfo -> TemplateInfo -> Struct -> HeapObject -> Object There's no public API method for retrieving the properties of a template but the internal method is TemplateInfo::property_list(). It returns either undefined (no properties) or a TemplateList (which is a FixedArray) that looks like [name1, details1, value1, name2, details2, value2, ...]. Names are strings or symbols. Hope that helps! -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-users/CAHQurc-bWrCa6_m4owhK3wA%2B-Zx2X72osMo3rz9nKj7R3BR3Cg%40mail.gmail.com.
