Yes, that helped. Thank you very much. On Tuesday, January 5, 2021 at 3:19:12 AM UTC-8, Ben Noordhuis wrote: > > On Tue, Jan 5, 2021 at 3:05 AM Ron Prestenback <ronpres...@gmail.com > <javascript:>> 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! >
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