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  • Storing a type in C++

    - by perimosocordiae
    Is it possible to store a type name as a C++ variable? For example, like this: type my_type = int; // or string, or Foo, or any other type void* data = ...; my_type* a = (my_type*) data; I know that 99.9% of the time there's a better way to do what you want without resorting to casting void pointers, but I'm curious if C++ allows this sort of thing.

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  • Sorting and displaying a custom QVariant type.

    - by Kranar
    Hello, I have a custom type I'd like to use with QVariant but I don't know how to get the QVariant to display in a table or have it sort in a QSortFilterProxyModel. I register the type with Q_DECLARE_METATYPE and wrote streaming operators registered via qRegisterMetaTypeStreamOperators but for whatever reason when I use the type with a table model, it doesn't display anything and it doesn't sort. I should specify that this custom type can not be modified. It has a copy and default constructor, but I can not go in and modify the source code to get it to work with QVariant. Is there a way of non-intrusively getting the behaviour I'd like?

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  • Using generic type from other generic parameter

    - by DEHAAS
    Hi, I have a question about .net generics. Consider the following code: public class Test<TKey> { TKey Key { get; set; } } public class Wrapper<TValue, TKey> where TValue : Test<TKey> { public TValue Value { get; set; } } Now, when using this code, I could do something like this: Wrapper<Test<int>, int> wrapper = new Wrapper<Test<int>, int>(); The int type parameter has to be provided twice. Is it possible to modify the Wrapper definition, to require TValue to be a generic type, and use this 'nested' generic type parameter insted of the TKey type parameter?

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  • What type of objects can be sent back to an action Method using HTML.HIDDEN()

    - by Richard77
    Hello, 1)Let's say I've this form: <%Using(Html.BeginForm()){%> <% = Html.Hidden("myObject", (cast to the appropriate type)ViewData["KeyForMyObject"]%> <input type = "submit" "Submit Object"> <%}%> 2) Here's the Action which's supposed to intercept the value of the object public ActionResult MyAction(Type myObject) { //Do Something with the object } Here's my question: What type of objects the Hidden field can support? In fact, when ViewData["KeyForMyObject"] contains a string, int, or bool, myAction is able to retrieve the value. But, when it comes to objects, such as List, and dictionary, nothing happens. When I debug to check the local values, I see null for Type myObject in the MyMethod. So what are the rules in MVC when it comes to a List or Dictionary? ================================= EDIT To make things simpler, can I write something like this <% = Html.Hidden("contactDic", (Dictionary<string, string>) ViewData["contacts"])%> and expect to retrieve the dictionary in the action Method like this public ActionResult myMethod(Dictionary<string, string> contactDic) { //Do something with the dictionary } Thanks for Helping

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  • Incompatible pointer type

    - by Boffin
    Hello. I have the function with following signature: void box_sort(int**, int, int) and variable of following type: int boxes[MAX_BOXES][MAX_DIMENSIONALITY+1] When I am calling the function box_sort(boxes, a, b) GCC gives me two warnings: 103.c:79: warning: passing argument 1 of ‘box_sort’ from incompatible pointer type (string where i am calling the function) 103.c:42: note: expected ‘int **’ but argument is of type ‘int (*)[11] (string where the function is defined) The question is why? Whether int x[][] and int** x (and actually int* x[]) are not the same types in C?

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  • How to implement table-per-concrete-type using entity framework

    - by SDReyes
    Hello Guys! I'm mapping a set of tables that share a common set of fields: So as you can see I'm using a table-per-concrete-type strategy to map the inheritance. But... I have not could to relate them to an abstract type containing these common properties. It's possible to do it using EF? BONUS: The only non documented Entity Data Model Mapping Scenario is Table-per-concrete-type inheritance http://msdn.microsoft.com/en-us/library/cc716779.aspx : P

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  • How to convert string to any type

    - by DJPB
    Hi there I want to convert a string to a generic type I have this: string inputValue = myTxtBox.Text; PropertyInfo propInfo = typeof(MyClass).GetProperty(myPropertyName); Type propType = propInfo.PropertyType; object propValue = ????? I want to convert 'inputString' to the type of that property, to check if it's compatible how can I do that? tks

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  • <button type="submit"> compatibility?

    - by Mark
    I'd like to have a submit button that submits a different value than is displayed on the button. With <input type="submit"> you can't seem to do this. With <button type="submit"> however, these can be two different values. The question is, will it work in all browsers? Trying this test code here: <form method="get" action=""> <input type="text" name="txt"/> <button type="submit" name="btn" value="val">text</button> </form> In FF 3.6 it updates my address bar with both values appropriately (and responds to me pressing enter in the text box). In IE 8, it also accepts pressing enter, displays the text value in the address bar, but it show the button's value as a GET param at all... does that mean it's not submitting it?

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  • jquery.ajax returns content-type "html" on iis while it returns content-type "json" on local host

    - by Sridhar
    Hi, I am using jQuery.ajax function to make an ajax call to a page method in asp.net. I specifically set the content-type to "application/json; charset=utf-8". When I looked at the response in the firebug it says the content-type is html. Following is the code to my ajax call $.ajax({ async: asyncVal, type: "POST", url: url + '/' + webMethod, data: dataPackage, contentType: "application/json; charset=UTF-8", dataType: "json", error: errorFunction, success: successFunction });

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  • Dictionary as parameter, where the Value-Type is irrelevant

    - by aaginor
    Hi folks, I have a function, that returns the next higher value of a Dictionary-Keys-List compared to a given value. If we have a Key-List of {1, 4, 10, 24} and a given value of 8, the function would return 10. Obviously the type of the Value-Part of the Dictionary doesn't matter for the function, the function-code for a Dictionary<int, int> and Dictionary<int, myClass> would be the same. How has the method-head have to look like, when I want to call the function with any Dictionary, that has int as key-Type and the value-Type is irrelevant? I tried: private int GetClosedKey(Dictionary<int, object> list, int theValue); but it says that there are illegal arguments, when I call it with a Dictionary. I don't want to copy'n'paste the function for each different value-type that my function may be called. Any idea, how to accomplish that? Thanks in advance, Frank

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  • the way to get a value from a hidden type correctly

    - by kawtousse
    hey, in a html table i construct in each row an edit buttton like the following: retour.append("<input type=\"hidden\" id=\"id_"+nomTab+"_"+compteur+"\" value=\""+object.getIdDailyTimeSheet()+"\" name=\"hd_"+compteur+"\" />"); this is the hidden type then i do the following: retour.append("<button id=edit name=edit type=button onClick= editarow()>"); retour.append("<img src=edit.gif />"); retour.append("</button>"); retour.append("</td>"); here i am using the hidden type to differenciate between my rows with it. Now I am trying to get the parameter called here: value=\""+object.getIdDailyTimeSheet() in my servlet to do an update query based on the IdDailyTimeSheet. I didn't untill know find the way to get this value every time i click the edit button (i do its submit with the javascript). thanks for help.

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  • Objective C - creating concrete class instances from base class depending upon type

    - by indiantroy
    Just to give a real world example, say the base class is Vehicle and concrete classes are TwoWheeler and FourWheeler. Now the type of the vehicle - TwoWheeler or FourWheeler, is decided by the base class Vehicle. When I create an instance of TwoWheeler/FourWheeler using alloc-init method, it calls the super implementation like below to set the value of common properties defined in the Vehicle class and out of these properties one of them is type that actually decides if the type is TwoWheeler or FourWheeler. if (self = [super initWithDictionary:dict]){ [self setOtherAttributes:dict]; return self; } Now when I get a collection of vehicles some of them could be TwoWheeler and others will be FourWheeler. Hence I cannot directly create an instance of TwoWheeler or FourWheeler like this Vehicle *v = [[TwoWheeler alloc] initWithDictionary:dict]; Is there any way I can create an instance of base class and once I know the type, create an instance of child class depending upon type and return it. With the current implementation, it would result in infinite loop because I call super implementation from concrete class. What would be the perfect design to handle this scenario when I don't know which concrete class should be instantiated beforehand?

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  • How to return a value based on the type of the generic T

    - by Blankman
    I have a method like: public T Get<T>(string key) { } Now say I want to return "hello" if the type is a string, and 110011 if it is type int. how can I do that? typeof(T) doesn't seem to work. I ideally want to do a switch statement, and return something based on the Type of the generic (string/int/long/etc). Is this possible?

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  • Mapping to a different view based on child type

    - by Ryan Burnham
    So i have a situation where i have common base type but i need to map to a different view based on the child type. It looks like i can use a generic mapping class to handle the inheritance http://geekswithblogs.net/nharrison/archive/2010/07/09/inheriting-a-class-map-in-fluent-nhibernate.aspx But how can i conditionally map to a different view based on the child type? I see an EntityType property but it says its obsolete and will be made private in the next version. As an example i have a base class of ContactInfo is standard between contact types but the values come from different places depending on the contact type, this I'll handle through the sql view.

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  • singledispatch in class, how to dispatch self type

    - by yanxinyou
    Using python3.4. Here I want use singledispatch to dispatch different type in __mul__ method . The code like this : class Vector(object): ## some code not paste @functools.singledispatch def __mul__(self, other): raise NotImplementedError("can't mul these type") @__mul__.register(int) @__mul__.register(object) # Becasue can't use Vector , I have to use object def _(self, other): result = Vector(len(self)) # start with vector of zeros for j in range(len(self)): result[j] = self[j]*other return result @__mul__.register(Vector) # how can I use the self't type @__mul__.register(object) # def _(self, other): pass # need impl As you can see the code , I want support Vector*Vertor , This has Name error Traceback (most recent call last): File "p_algorithms\vector.py", line 6, in <module> class Vector(object): File "p_algorithms\vector.py", line 84, in Vector @__mul__.register(Vector) # how can I use the self't type NameError: name 'Vector' is not defined The question may be How Can I use class Name a Type in the class's method ? I know c++ have font class statement . How python solve my problem ? And it is strange to see result = Vector(len(self)) where the Vector can be used in method body .

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  • can I get .class from generic type argument?

    - by Mike S
    I have the following class: public abstract class MyClass<T extends Object> { protected T createNewFromData(Reader reader){ GSON.fromJSON(reader,T.class); // T.class isn't allowed :( } } How do I pass a Class<T instance into there? Is there some wierd and wacky work around? Is there a way to get a Class<T reference other than from a pre-instantiated Object of type T? It won't let me do this either: T t = new T(); Class<T> klass = t.class; ANSWER BELOW Thanks to the accepted answer, here is the solution: Type type = new TypeToken<T>(){}.getType(); return gson.fromJson(reader, type);

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  • why Haskell can deduce [] type in this function

    - by Sili
    rho x = map (((flip mod) x).(\a -> a^2-1)) (rho x) This function will generate an infinite list. And I tested in GHCi, the function type is *Main> :t rho rho :: Integral b => b -> [b] If I define a function like this fun x = ((flip mod) x).(\a -> a^2-1) The type is *Main> :t fun fun :: Integral c => c -> c -> c My question is, how can Haskell deduce the function type to b - [b]? We don't have any [] type data in this function. Thanks!

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  • Finding the type of an object in C++

    - by lemnisca
    I have a class A and another class that inherits from it, B. I am overriding a function that accepts an object of type A as a parameter, so I have to accept an A. However, I later call functions that only B has, so I want to return false and not proceed if the object passed is not of type B. What is the best way to find out which type the object passed to my function is?

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  • how do i lock down my preferences for Services .mmc snapin column layout and view type

    - by gerryLowry
    when "Services" opens, it's in Extended View. i prefer Standard view. i also prefer this column layout: Status | Startup Type | Log On As | Name | Description because when I expand all columns via Ctrl+(numeric keypad "+") what i need to see most i can view without being forced to scroll to the right. Problem: my preferred layout does not persist. QUESTION: how can i force Windows (2008 R2, 7, XP, et cetera) to remmember my settings? thnx / g.

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