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  • simulate what native object is not exist

    - by Naitro
    Here is the situation: I have checking on existing class like: ('Promise' in window) // true/false` And I wanna force return false or true on it, can I do it? Yes, I can check it by some other way, like ` window.Promise = undefined; window.Promise === undefined; Or something like this, but can I somehow delete this object or simulate something for 'in' operator? I check specification and v8 code, there is 'in' operator just call 'HasProperty' operator, which realization on c++.. I know 'hack' with faking toString/valueOf methods: obj = { toString: function(){ return 'myName'; } }, obj2 = {}; obj2[obj] = 1; // Object {myName: 1} May be I can use it in some way? But, as I send string 'Promise' I can't just fake it like this way.. may be exist some way to fake 'HasProperty'?

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  • Advice on whether to use native C++ DLL or not: PINVOKE & Marshaling ?

    - by Bob
    What's the best way to do this....? I have some Native C++ code that uses a lot of Win32 calls together with byte buffers (allocated using HeapAlloc). I'd like to extend the code and make a C# GUI...and maybe later use a basic Win32 GUI (for use where there is no .Net and limited MFC support). (A) I could just re-write the code in C# and use multiple PINVOKEs....but even with the PINVOKES in a separate class, the code looks messy with all the marshaling. I'm also re-writing a lot of code. (B) I could create a native C++ DLL and use PINVOKE to marshal in the native data structures. I'm assuming I can include the native C++ DLL/LIB in a project using C#? (C) Create a mixed mode DLL (Native C++ class plus managed ref class). I'm assuming that this would make it easier to use the managed ref class in C#......but is this the case? Will the managed class handle all the marshaling? Can I use this mixed mode DLL on a platform with no .Net (i.e. still access the native C++ unmanaged component) or do I limit myself to .Net only platforms. One thing that bothers me about each of these options is all the marshalling. Is it better to create a managed data structure (array, string etc.) and pass that to the native C++ class, or, the other way around? Any ideas on what would be considered best practice...?

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  • Is there any functional difference between immutable value types and immutable reference types?

    - by Kendall Frey
    Value types are types which do not have an identity. When one variable is modified, other instances are not. Using Javascript syntax as an example, here is how a value type works. var foo = { a: 42 }; var bar = foo; bar.a = 0; // foo.a is still 42 Reference types are types which do have an identity. When one variable is modified, other instances are as well. Here is how a reference type works. var foo = { a: 42 }; var bar = foo; bar.a = 0; // foo.a is now 0 Note how the example uses mutatable objects to show the difference. If the objects were immutable, you couldn't do that, so that kind of testing for value/reference types doesn't work. Is there any functional difference between immutable value types and immutable reference types? Is there any algorithm that can tell the difference between a reference type and a value type if they are immutable? Reflection is cheating. I'm wondering this mostly out of curiosity.

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  • Nullable types and ?? operator C# [en-US]

    - by ruimachado
    Nullable types vs Non-nullable types   While developing our C# projects its frequent the null comparison operation to avoid null exceptions. This simple operation is mainly coded using the "var x = null" code example inside an if clause. However not all types of variables are nullable, which means that setting a variable to null is not allowed in every cases, it depends on what kind of type are you defining. But what if there was an extension to your non-nullable type that would convert your variable types to nullable? This extension really exists. As I said before in C# you have nullable types which represent all the values of an underlying type, and an additional null value and can be declared easily using "T?", where T is the type of the variable and for example the normal int type cannot be null, so its a non-nullable type, however if you define a "int?" your variable can be null, what you do is convert a non-nullable type to a nullable type. Example: int x=null;     Not allowed     int? x=null;   Allowed     While using nullable types you can check if a variable is null the same way you do it with nullable types:     But what about setting a default value when a certain variable is null?   In this cases the c# .net framework let you set a default value when you try to assign a nullable type to a non-nullable type, using the ?? operator. If you don't use this operator you can still catch the InvalidOperationException which is throw in this cases. For example  without the ?? operator :     Using the ?? operator your code becomes cleaner and more easy to read and you get a bonus, you can set a default value for multiple variables using the ?? in a chain set.     That’s it,   Thanks, Rui Machado rpmachado.wordpress.com

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  • Cannot iterate of a collection of Anonymous Types created from a LINQ Query in VB.NET

    - by Atari2600
    Ok everyone, I must be missing something here. Every LINQ example I have seen for VB.NET anonymous types claims I can do something like this: Dim Info As EnumerableRowCollection = pDataSet.Tables(0).AsEnumerable Dim Infos = From a In Info _ Select New With {.Prop1 = a("Prop1"), .Prop2 = a("Prop2"), .Prop3 = a("Prop3") } Now when I go to iterate through the collection(see example below), I get an error that says "Name "x" is not declared. For Each x in Infos ... Next It's like VB.NET doesn't understand that Infos is a collection of anonymous types created by LINQ and wants me to declare "x" as some type. (Wouldn't this defeat the purpose of an anonymous type?) I have added the references to System.Data.Linq and System.Data.DataSetExtensions to my project. Here is what I am importing with the class: Imports System.Linq Imports System.Linq.Enumerable Imports System.Linq.Queryable Imports System.Data.Linq Any ideas?

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  • C++ Types Impossible to Name

    - by Kirakun
    While reading Wikipedia's page on decltype, I was curious about the statement, Its [decltype's] primary intended use is in generic programming, where it is often difficult, or even impossible, to name types that depend on template parameters. While I can understand the difficulty part of that statement, what is an example where there is a need to name a type that cannot be named under C++03? EDIT: My point is that since everything in C++ has a declaration of types. Why would there ever be a case where it is impossible to name a type? Furthermore, aren't trait classes designed to yield type informations? Could trait classes be an alternative to decltype?

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  • C#: Get key and value types of non-generic IDictionary at runtime

    - by Yang Zou
    there. I am wondering how I can get the key and value types of a non-generic IDictionary at runtime. For generic IDictionary, we can use reflection to get the generic arguments, which has been answered here. But for non-generic IDictionary, for instance, HybridDictionary, how can I get the key and value types? Thanks. Edit: I may not describe my problem properly. For non-generic IDictionary, if I have HyBridDictionary, which is declared as HyBridDictionary dict = new HyBridDictionary(); dict.Add("foo" , 1); dict.Add("bar", 2); How can I find out the type of the key is string and type of the value is int? Did I make the question clear? Thanks.

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  • assembly.GetTypes() does not return all types

    - by meta
    I try to lead the types from an .dll (which is also referenced in the executing project). I call: public static void LoadPlugin(string pluginFile) { Assembly assembly = Assembly.LoadFrom(pluginFile); foreach (Type type in assembly.GetTypes()) { // play with it } } It loads just a few of them: public partial class Mathematics : UserControl, IMathematics, IPortable and public partial class Welcome : UserControl but the next one, and some others, are ignored: public partial class Test : UserControl, ITest, IPortable They all stand in the same assembly, under the same namespace. The public static void LoadPlugin(string pluginFile) method is located in other assembly that is also referenced in the executing project. No exceptions are thrown. What could be the issues for not loading all the types? Any ideas?

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  • f# types' properties in inconsistent order and of slightly differing types

    - by philbrowndotcom
    I'm trying to iterate through an array of objects and recursively print out each objects properties. Here is my object model: type firmIdentifier = { firmId: int ; firmName: string ; } type authorIdentifier = { authorId: int ; authorName: string ; firm: firmIdentifier ; } type denormalizedSuggestedTradeRecommendations = { id: int ; ticker: string ; direction: string ; author: authorIdentifier ; } Here is how I am instantiating my objects: let getMyIdeasIdeas = [| {id=1; ticker="msfqt"; direction="buy"; author={authorId=0; authorName="john Smith"; firm={firmId=12; firmName="Firm1"}};}; {id=2; ticker="goog"; direction="sell"; author={authorId=1; authorName="Bill Jones"; firm={firmId=13; firmName="ABC Financial"}};}; {id=3; ticker="DFHF"; direction="buy"; author={authorId=2; authorName="Ron James"; firm={firmId=2; firmName="DEFFirm"}};}|] And here is my algorithm to iterate, recurse and print: let rec recurseObj (sb : StringBuilder) o= let props : PropertyInfo [] = o.GetType().GetProperties() sb.Append( o.GetType().ToString()) |> ignore for x in props do let getMethod = x.GetGetMethod() let value = getMethod.Invoke(o, Array.empty) ignore <| match value with | :? float | :? int | :? string | :? bool as f -> sb.Append(x.Name + ": " + f.ToString() + "," ) |> ignore | _ -> recurseObj sb value for x in getMyIdeas do recurseObj sb x sb.Append("\r\n") |> ignore If you couldnt tell, I'm trying to create a csv file and am printing out the types for debugging purposes. The problem is, the first element comes through in the order you'd expect, but all subsequent elements come through with a slightly different (and confusing) ordering of the "child" properties like so: RpcMethods+denormalizedSuggestedTradeRecommendationsid: 1,ticker: msfqt,direction: buy,RpcMethods+authorIdentifierauthorId: 0,authorName: john Smith,RpcMethods+firmIdentifierfirmId: 12,firmName: Firm1, RpcMethods+denormalizedSuggestedTradeRecommendationsid: 2,ticker: goog,direction: sell,RpcMethods+authorIdentifierauthorName: Bill Jones,RpcMethods+firmIdentifierfirmName: ABC Financial,firmId: 13,authorId: 1, RpcMethods+denormalizedSuggestedTradeRecommendationsid: 3,ticker: DFHF,direction: buy,RpcMethods+authorIdentifierauthorName: Ron James,RpcMethods+firmIdentifierfirmName: DEFFirm,firmId: 2,authorId: 2, Any idea what is going on here?

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  • Instantiating a list of parameterized types, making beter use of Generics and Linq

    - by DanO
    I'm hashing a file with one or more hash algorithms. When I tried to parametrize which hash types I want, it got a lot messier than I was hoping. I think I'm missing a chance to make better use of generics or LINQ. I also don't like that I have to use a Type[] as the parameter instead of limiting it to a more specific set of type (HashAlgorithm descendants), I'd like to specify types as the parameter and let this method do the constructing, but maybe this would look better if I had the caller new-up instances of HashAlgorithm to pass in? public List<string> ComputeMultipleHashesOnFile(string filename, Type[] hashClassTypes) { var hashClassInstances = new List<HashAlgorithm>(); var cryptoStreams = new List<CryptoStream>(); FileStream fs = File.OpenRead(filename); Stream cryptoStream = fs; foreach (var hashClassType in hashClassTypes) { object obj = Activator.CreateInstance(hashClassType); var cs = new CryptoStream(cryptoStream, (HashAlgorithm)obj, CryptoStreamMode.Read); hashClassInstances.Add((HashAlgorithm)obj); cryptoStreams.Add(cs); cryptoStream = cs; } CryptoStream cs1 = cryptoStreams.Last(); byte[] scratch = new byte[1 << 16]; int bytesRead; do { bytesRead = cs1.Read(scratch, 0, scratch.Length); } while (bytesRead > 0); foreach (var stream in cryptoStreams) { stream.Close(); } foreach (var hashClassInstance in hashClassInstances) { Console.WriteLine("{0} hash = {1}", hashClassInstance.ToString(), HexStr(hashClassInstance.Hash).ToLower()); } }

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  • How to: Show wait cursor in managed and native code

    - by TechTwaddle
    Someone on the MSDN forum asked about how to show a wait cursor, like when your application is loading or performing some (background) task. It’s pretty simple to show the wait cursor in both managed and native code, and in this post we will see just how. Managed Code (C#) Set Cursor.Current to Cursors.WaitCursor, and call Cursor.Show(). And to come back to normal cursor, set Cursor.Current to Cursors.Default and call Show() again. Below is a button handler for a sample app that I made, (watch the video below) private void button1_Click(object sender, EventArgs e) {     lblProgress.Text = "Downloading ether...";     lblProgress.Update();     Cursor.Current = Cursors.WaitCursor;     Cursor.Show();     //do some processing     for (int i = 0; i < 50; i++)     {         progressBar1.Value = 2 * (i + 1);         Thread.Sleep(100);     }     Cursor.Current = Cursors.Default;     Cursor.Show();     lblProgress.Text = "Download complete.";     lblProgress.Update(); }   Native Code In native code, call SetCursor(LoadCursor(NULL, IDC_WAIT)); to show the wait cursor; and SetCursor(LoadCursor(NULL, IDC_ARROW)); to come back to normal. The same button handler for native version of the app is below, case IDC_BUTTON_DOWNLOAD:     {         HWND temp;         temp = GetDlgItem(hDlg, IDC_STATIC_PROGRESS);         SetWindowText(temp, L"Downloading ether...");         UpdateWindow(temp);         SetCursor(LoadCursor(NULL, IDC_WAIT));         temp = GetDlgItem(hDlg, IDC_PROGRESSBAR);         for (int i=0; i<50; i++)         {             SendMessage(temp, PBM_SETPOS, (i+1)*2, 0);             Sleep(100);         }         SetCursor(LoadCursor(NULL, IDC_ARROW));         temp = GetDlgItem(hDlg, IDC_STATIC_PROGRESS);         SetWindowText(temp, L"Download Complete.");         UpdateWindow(temp);     }     break; Here is a video of the sample app running. First the managed version is deployed and the native version next,

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  • Script language native extensions - avoiding name collisions and cluttering others' namespace

    - by H2CO3
    I have developed a small scripting language and I've just started writing the very first native library bindings. This is practically the first time I'm writing a native extension to a script language, so I've run into a conceptual issue. I'd like to write glue code for popular libraries so that they can be used from this language, and because of the design of the engine I've written, this is achieved using an array of C structs describing the function name visible by the virtual machine, along with a function pointer. Thus, a native binding is really just a global array variable, and now I must obviously give it a (preferably good) name. In C, it's idiomatic to put one's own functions in a "namespace" by prepending a custom prefix to function names, as in myscript_parse_source() or myscript_run_bytecode(). The custom name shall ideally describe the name of the library which it is part of. Here arises the confusion. Let's say I'm writing a binding for libcURL. In this case, it seems reasonable to call my extension library curl_myscript_binding, like this: MYSCRIPT_API const MyScriptExtFunc curl_myscript_lib[10]; But now this collides with the curl namespace. (I have even thought about calling it curlmyscript_lib but unfortunately, libcURL does not exclusively use the curl_ prefix -- the public APIs contain macros like CURLCODE_* and CURLOPT_*, so I assume this would clutter the namespace as well.) Another option would be to declare it as myscript_curl_lib, but that's good only as long as I'm the only one who writes bindings (since I know what I am doing with my namespace). As soon as other contributors start to add their own native bindings, they now clutter the myscript namespace. (I've done some research, and it seems that for example the Perl cURL binding follows this pattern. Not sure what I should think about that...) So how do you suggest I name my variables? Are there any general guidelines that should be followed?

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  • C# 4: Real-World Example of Dynamic Types

    - by routeNpingme
    I think I have my brain halfway wrapped around the Dynamic Types concept in C# 4, but can't for the life of me figure out a scenario where I'd actually want to use it. I'm sure there are many, but I'm just having trouble making the connection as to how I could engineer a solution that is better solved with dynamics as opposed to interfaces, dependency injection, etc. So, what's a real-world application scenario where dynamic type usage is appropriate?

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  • Silverlight 4 Data Binding with anonymous types.

    - by Anthony
    Does anyone know if you can use data binding with anonymous types in Silverlight 4? I know you can't in previous versions of silverlight, you can only databind to public class properties and anonymous type properties are internal. Just wondering if anyone has tried it in silverlight 4? Thanks in advanced

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  • Unpacking tuple types in Scala

    - by jpalecek
    I was just wondering, can I decompose a tuple type into its components' types in Scala? I mean, something like this trait Container { type Element } trait AssociativeContainer extends Container { type Element <: (Unit, Unit) def get(x : Element#First) : Element#Second }

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  • Design Patterns : Question about "Types"

    - by contactmatt
    Would someone please explain to me what the below paragraph means? This is a snippet from "Design Patterns: Elements of Reusable OO software" Part of an object's interface may be characterized by one type, and other parts by other types. Two objects of the same type need only share parts of their interfaces. Interfaces can contain other interfaces as subsets. - Design Patterns - Elements of Reusable OO software, pg 13

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  • Determining if types alias to the same underlying type in C++

    - by emchristiansen
    I'd like to write a templated function which changes its behavior depending on template class types passed in. To do this, I'd like to determine the type passed in. For example, something like this: template <class T> void foo() { if (T == int) { // Sadly, this sort of comparison doesn't work printf("Template parameter was int\n"); } else if (T == char) { printf("Template parameter was char\n"); } } Is this possible?

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  • Describing Types question

    - by user288245
    I have a bunch of types (eg. LargePlane, SmallPlane) that could be in this collection i've made, how do i print like LargePlane? I've tried like typeOf() and stuff but it doesn't work. Within like a toString()? So when i output the collection it states what type it is.

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  • Performance surprise with "as" and nullable types

    - by Jon Skeet
    I'm just revising chapter 4 of C# in Depth which deals with nullable types, and I'm adding a section about using the "as" operator, which allows you to write: object o = ...; int? x = o as int?; if (x.HasValue) { ... // Use x.Value in here } I thought this was really neat, and that it could improve performance over the C# 1 equivalent, using "is" followed by a cast - after all, this way we only need to ask for dynamic type checking once, and then a simple value check. This appears not to be the case, however. I've included a sample test app below, which basically sums all the integers within an object array - but the array contains a lot of null references and string references as well as boxed integers. The benchmark measures the code you'd have to use in C# 1, the code using the "as" operator, and just for kicks a LINQ solution. To my astonishment, the C# 1 code is 20 times faster in this case - and even the LINQ code (which I'd have expected to be slower, given the iterators involved) beats the "as" code. Is the .NET implementation of isinst for nullable types just really slow? Is it the additional unbox.any that causes the problem? Is there another explanation for this? At the moment it feels like I'm going to have to include a warning against using this in performance sensitive situations... Results: Cast: 10000000 : 121 As: 10000000 : 2211 LINQ: 10000000 : 2143 Code: using System; using System.Diagnostics; using System.Linq; class Test { const int Size = 30000000; static void Main() { object[] values = new object[Size]; for (int i = 0; i < Size - 2; i += 3) { values[i] = null; values[i+1] = ""; values[i+2] = 1; } FindSumWithCast(values); FindSumWithAs(values); FindSumWithLinq(values); } static void FindSumWithCast(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is int) { int x = (int) o; sum += x; } } sw.Stop(); Console.WriteLine("Cast: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithAs(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { int? x = o as int?; if (x.HasValue) { sum += x.Value; } } sw.Stop(); Console.WriteLine("As: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithLinq(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = values.OfType<int>().Sum(); sw.Stop(); Console.WriteLine("LINQ: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } }

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  • Make a compiled binary run at native speed flawlessly without recompiling from source on a another system?

    - by unknownthreat
    I know that many people, at a first glance of the question, may immediately yell out "Java", but no, I know Java's qualities. Allow me to elaborate my question first. Normally, when we want our program to run at a native speed on a system, whether it be Windows, Mac OS X, or Linux, we need to compile from source codes. If you want to run a program of another system in your system, you need to use a virtual machine or an emulator. While these tools allow you to use the program you need on the non-native OS, they sometimes have problems of performance and glitches. We also have a newer compiler called "JIT Compiler", where the compiler will parse the bytecode program to native machine language before execution. The performance may increase to a very good extent with JIT Compiler, but the performance is still not the same as running it on a native system. Another program on Linux, WINE, is also a good tool for running Windows program on Linux system. I have tried running Team Fortress 2 on it, and tried experiment with some settings. I got ~40 fps on Windows at its mid-high setting on 1280 x 1024. On Linux, I need to turn everything low at 1280 x 1024 to get ~40 fps. There are 2 notable things though: Polygon model settings do not seem to affect framerate whether I set it low or high. When there are post-processing effects or some special effects that require manipulation of drawn pixels of the current frame, the framerate will drop to 10-20 fps. From this point, I can see that normal polygon rendering is just fine, but when it comes to newer rendering methods that requires graphic card to the job, it slows down to a crawl. Anyway, this question is rather theoretical. Is there anything we can do at all? I see that WINE can run STEAM and Team Fortress 2. Although there are flaws, they can run at lower setting. Or perhaps, I should also ask, "is it possible to translate one whole program on a system to another system without recompiling from source and get native speed?" I see that we also have AOT Compiler, is it possible to use it for something like this? Or there are so many constraints (such as DirectX call or differences in software architecture) that make it impossible to have a flawless and not native to the system program that runs at native speed?

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  • Chrome Apps + Native Client

    Chrome Apps + Native Client Did you know that you can use Native Client inside a Chrome App? Join +John Mccutchan and +Pete LePage as they introduce Native Client Acceleration Modules (NaCl AM) which expose C++ libraries to JavaScript programs. NaCl AMs can, be used for bulk data processing (compression, encryption) but they also work well in interactive applications that require low latency. We'll explain how to build a NaCl Acceleration Module and demo a Bullet Physics engine running inside a Chrome App with a NaCl AM interacting with an HTML and JavaScript UI using three.js. We'll be live on Tuesday December 11th at at 9am PT, showing you code, samples and answering your questions. From: GoogleDevelopers Views: 0 0 ratings Time: 45:00 More in Science & Technology

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