variant Questions

2

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I hit the limit of 50 types in boost::variant. I found this nice self-contained header but it lacks the multi visitation feature (I actually need the double visitation). I tried to look a bit afte...
Racoon asked 4/6, 2014 at 16:28

1

I'm attempting to call RNGCryptoServiceProvider->GetBytes() from PHP via the COM layer. I can get it to connect to the class, but every time I call the method, I get one of two errors (relating to ...
Traps asked 27/6, 2011 at 19:8

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I am trying to take a variant variable and convert it into a string so that I can run a split function on the data. However, whenever I try to redefine the variant I get a type mismatch error. I ha...
Defensive asked 17/3, 2014 at 13:56

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Here's the problem: I am currently trying to create a simple stack-based programming language (Reverse Polish Notation, FORTH style) as a component of a larger project. I have hit a snag, though. ...
Dallas asked 16/2, 2014 at 0:16

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I'm trying to get rid of dependencies on SCRRUN.DLL in a VB6 application. One of the things it's currently being used for is its Dictionary class. The Dictionary class has a Keys function that is s...
Mccalla asked 12/12, 2013 at 21:51

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I think Boost::variant is busted in 1_54. I am trying to use a std::unique_ptr with as a bounded type in boost variant. According to the 1_54 documentation, variant needs to be copy constructable...
Above asked 1/11, 2013 at 0:3

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There is no direct support for variant types (aka tagged unions, discriminated unions) in C#. However one can go with a visitor pattern that enables discrimination via double-dispatching and guaran...
Washcloth asked 14/10, 2013 at 1:40

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I'm trying to write overloads of operator<< for specific instantiations of standard library containers that will be stored in a boost::variant. Here's a small example that illustrates the pro...

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I have an object, that has one value, but that value can either be an integer, string, boolean or TDateTime. So, it is a Variant. I use VarType() to check its type, but since VarType() has no 'var...
Radford asked 13/3, 2013 at 13:59

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uses SysUtils, Variants; var VariantSingle: Variant; VTSingle: TVarType; SingleTest: Single; VariantDouble: Variant; DoubleTest: Double; VTDouble: TVarType; begin SingleTest := 1.234; Va...
Gamez asked 28/2, 2013 at 10:46

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A leak checker tells me that I have a memory leak on memory that is allocated in the following code: // Get the value from the object as a variant. VARIANT vVal; VariantInit ( &vVal ); hres = ...
Smail asked 9/1, 2013 at 19:56

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I have this current code, which types "AAPL" into an excel sheet, and the returns the corresponding value. I would like to make it so that after cout << "Ticker: "; i can type in a ticker s...
Wingate asked 25/12, 2012 at 23:29

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Type inference makes use of the var keyword. The compiler "infers" what the type of the variable is by what the variable is initialized to. e.g. var somenum=o; becomes int somenum=0; Even though s...
Flavescent asked 15/11, 2012 at 14:42

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i am trying to call a method of COM object, where one of the documented parameters is an "array of bytes". The actual declartion depends on the per-language documentation you're looking at: in C#...
Unintentional asked 15/8, 2012 at 21:44

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So I am working on an Excel Project that is going to load a C++ dll using VBA. What I'd like to do is to be able to pass an Excel range with no specific type (data can be numerical or categorical) ...
Billon asked 16/7, 2012 at 16:12

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OCaml gives function `A -> 1 | _ -> 0 the type [> `A] -> int, but why isn't that [> ] -> int? This is my reasoning: function `B -> 0 has type [<`B] -> int. Adding a `A...
Kutzer asked 26/5, 2012 at 19:6

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I have a TDateTime value (that I get as result from EndOfTheMonth(date)) to a variant type. The result is wrongly rounded. Let's have a look at example: data := EndOfTheMonth(date); V := data; ...
Efferent asked 5/4, 2012 at 11:32

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I am trying to convert the following two interfaces from a C header file to a Delphi PAS unit but have run into strange problems when using the ones I did myself. I need help understanding how to i...
Leaven asked 18/3, 2012 at 10:2

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I have such code: boost::variant<b2DistanceJointDef, b2FrictionJointDef, b2GearJointDef, b2MouseJointDef, b2PrismaticJointDef, b2PulleyJointDef, b2RevoluteJointDef, b2RopeJointDef, b2WeldJoin...
Pitchman asked 9/3, 2012 at 9:52

4

I have a large VB6 projects where a lot of variables don't have an explicitly defined type, so they automaticly default to Variant type. Finding all those by hand is a massive task, so is there any...
Enyo asked 19/1, 2012 at 13:0

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I am designing a communication middleware for use in an application which has a module in Ada and many modules in C++ which communicates passing parameters (scalar values) and structures. The appli...
Indreetloire asked 3/11, 2011 at 11:52

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1) I have an open union defined as follows: type 'a choice = [> `One | `Other ] as 'a I then try to define a type choice_list: type choice_list = choice list which does not work. How does ...
Fortenberry asked 2/11, 2011 at 14:37

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Why does this work fine? module Account = struct type account_type = Current of float | Savings of float end let sarah = Account.Current 100.0;; While the final line in the following produce...
Sukkoth asked 27/10, 2011 at 15:35

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here is a snippet showing what I am trying to achieve: type TMyObject<T> = class (TObject) function GetVarType(Value: T): TVarType; end; function TMyObject<T>.GetVarType(Value: T)...
Tarlatan asked 25/10, 2011 at 15:55

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A question on variants. Im aware that variants in Excel vba are both the default data type and also inefficient (from the viewpoint of overuse in large apps). However, I regularly use them for stor...
Empery asked 22/9, 2011 at 11:11

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