variant

I realize that it goes against the strongly typed nature of C#, but I find that when working with dynamic objects in the language, some of the more useful features typically found in JavaScript or PowerShell are simply not practical. For example, the following C# code will fail at runtime and it's obvious why. dynamic x = 1.0; int y = x; But that makes the dynamic features of C# pretty limited when dealing with loosely typed data such as that produced by JSON payloads or CSV where subtle variations in the representation can result in very different behavior at runtime. What I'm looking for is

What is the right way to receive and send arrays over COM? Here's my attempt so far: a safearray of doubles wrapped in a variant. //takes variant holding safearray of doubles //returns a similar variant having multipled every element by 2 STDMETHODIMP MyComClass::safearraytimestwo(VARIANT in, VARIANT* out) { CComSafeArray<double> sa_in; sa_in.Attach(*in.pparray); ULONG size = sa_in.GetCount(); CComSafeArray<double> *out_sa = new CComSafeArray<double>(size); for (long i=0;i<size;i++) out_sa->SetAt(i,sa_in[i]*2); out = new CComVariant(out_sa); return S_OK; } Problems: - currently compilation

my function gets a collection and the items may be Objects or primitives how can I assign the item to a variant? What I do now looks something like this: Dim vItem As Variant On Error Resume Next vItem = oCollection.Item(sKey) If Err.Number = 91 Then Set vItem = oCollection.Item(sKey) On Error GoTo 0 I think it works, but I wonder if there is a better way to do it. SWa You may use the varType() function to test the type, alternatively if you are testing for specific types, you could use typeof. If VarType(oCollection.Item(sKey)) = vbObject Then Set vItem = oCollection.Item(sKey) Else vItem =

Hy there, I'm trying to adapt an existing code to boost::variant. The idea is to use boost::variant for a heterogeneous vector. The problem is that the rest of the code use iterators to access the elements of the vector. Is there a way to use the boost::variant with iterators? I've tried typedef boost::variant<Foo, Bar> Variant; std::vector<Variant> bag; std::vector<Variant>::iterator it; for(it= bag.begin(); it != bag.end(); ++it){ cout<<(*it)<<endl; } But it didn't work. EDIT: Thank you for your help! But in my design, I need to get one element from the list and pass it around other parts of

I have a situation where a function must return a value taken from a table. A cell in this table (let's assume the table just works...) may contain a value, or it might not. This value can also be one of several types: int, double, string, date (but no other type). What would such a function return? Is it a good idea to return std::optional<std::variant<std::string, int, double, std::chrono::time_point>> ? Would that be a good use of optional and variant ? I would consider this to be a useful use of std::monostate . Specifically, variant<std::monostate, int, double, std::string, std::chrono:

Are there any easy-to-use , high-level classes or libraries that let you interact with VARIANT s in Visual C++? More specifically, I'd like to convert between POD types (e.g. double , long ), strings (e.g. CString ), and containers (e.g. std::vector ) and VARIANT s. For example: long val = 42; VARIANT var; if (ToVariant(val, var)) ... // tries to convert long -> VARIANT comObjPtr->someFunc(var); std::vector<double> vec; VARIANT var = comObjPtr->otherFunc(); if (FromVariant(var, vec)) ... // tries VARIANT -> std::vector<double> I (naively?) assumed that people working with COM do this all the