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  • Can I use foreach to return only a certain type from a collection?

    - by RoboShop
    If I enter the code below, I get an error. Basically, the foreach will break when it comes across a Control that isn't a label. foreach (Label currControl in this.Controls()) { ... } I have to do something like this. foreach (Control currControl in this.Controls()) { if(typeof(Label).Equals(currControl.GetType())){ ... } } can anyone think of a better way of doing it without me needing to check the type? Can I somehow get foreach to skip the objects that aren't Labels?

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  • how do i use MySql ENUM type? (and is it right for a news feed)

    - by Haroldo
    I'm creating a table called news_feed, this will log all the actions a user performs. Lets say I want to store user1234 deleted article412 at midday I then need a table like so timestamp | user_id | subject_type | subject_id | method . there would be 5 potential methods to log, methods = add/edit/delete/update/report and lets say 2 possible subject_type subjects = article/comment I know i could make my own key where 0=add, 1=delete etc etc but this would make my queries cumbersome to use/write as i'd need to keep consulting the key. Is there a MySql type which can read lots of identially values quickly? is this ENUM? how do i use it?!!

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  • Why would this line throw exception for type initializer failed?

    - by Jaggu
    I had a class: public class Constant { public static string ConnString = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString; } which would throw exception on LIVE: Type initialize failed for Constant ctor If I change the class to: public class Constant { public static string ConnString { get { return ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString; } } } it works. I wasted 2 hours behind this but I still don't know why would this happen. Any ideas? Note: The 1st class used to work on DEV environment but not on LIVE. The 2nd class works on DEV and also on Production. I am using VS2010 on production and Asp.Net 4.0 Website project. I am totally amazed by this inconsistency to say the least! Edit: This class was in App_Code folder.

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  • What is the proper way to declare a specialization of a template for another template type?

    - by Head Geek
    The usual definition for a specialization of a template function is something like this: class Foo { [...] }; namespace std { template<> void swap(Foo& left, Foo& right) { [...] } } // namespace std But how do you properly define the specialization when the type it's specialized on is itself a template? Here's what I've got: template <size_t Bits> class fixed { [...] }; namespace std { template<size_t Bits> void swap(fixed<Bits>& left, fixed<Bits>& right) { [...] } } // namespace std Is this the right way to declare swap? It's supposed to be a specialization of the template function std::swap, but I can't tell whether the compiler is seeing it as such, or whether it thinks that it's an overload of it or something.

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  • help designing a method, should I use out or ref or return the type?

    - by Blankman
    I have a method that I will use in the following contexts: 1. User user = null; if(...) { user = defaultUser; SetUser(a,b,user); } else { SetUser(a,b,user); } SaveUser(user); So some cases are where user may be null, while in other cases it will already be initialized. How should I design the SetUser method? I currently have it like so, but this causes an error when user is null. public void SetUser(object a, object b, User user) { if(user == null) user = new User(); user.Security = a.security; user.Blah = b.type; }

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  • Return type value if RunTimeException has been thrown and not catched.

    - by Alfred
    I am using Gson to parse Json. What I don't understand what the return type will be if you don't catch the Runtime Exception. I was expecting it to be null, but it is not null when evaluating with a simple if statement. My code looks something like this: public X x() { return gson.fromJson(jsonString, X.class); } then from another function I call the function: public void y() { final X x = x(); if (x == null) { System.out.println("x == null") } } I was expecting x to be null, but it isn't because the print statement is not called? What is the value of x? How can if them. I have my problem by using a catch block in the x() function and returning null. But I am just wondering what the value of function x() is(if any?)? Hopefully I make any sense at all.

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  • What data type should I use for my texture coordinates in OpenGL ES?

    - by Matthew Chen
    I notice that the default data type for texture coordinates in the OpenGL docs is GLfloat, but much of the sample code I see written by experienced iphone developers uses GLshort or GLbyte. Is this an optimization? GLfloat vertices[] = { // Upper left x1, y2, // Lower left x1, y1, // Lower right x2, y1, // Upper right x2, y2, }; glTexCoordPointer(2, GL_FLOAT, 0, iconSTs); vs. GLbyte vertices[] = { // Upper left x1, y2, // Lower left x1, y1, // Lower right x2, y1, // Upper right x2, y2, }; glTexCoordPointer(2, GL_BYTE, 0, iconSTs);

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  • For what purpose does java have a float primitive type?

    - by Roman
    I heard plenty times different claims about float type in java. The most popular issues typicaly regard to converting float value to double and vice versa. I read (rather long time ago and not sure that it's actual now with new JVM) that float gives much worse performance then double. And it's also not recommended to use float in scientific applications which should have certain accuracy. I also remember that when I worked with AWT and Swing I had some problems with using float or double (like using Point2D.Float or Point2D.Double). So, I see only 2 advantages of float over double: it needs only 4 bytes while double needs 8 bytes JMM garantees that assignment operation is atomic with float variables while it's not atomic with double's. Are there any other cases where float is better then double? Do you use float's in your applications? It seems to me that the only valuable reason java has float is backward compatibility.

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  • How can I type cast EventArgs to have a .point property in c#? [closed]

    - by Sean Smyth
    I'm working with a double click function in c#. the function takes an object and EventArgs as it's parameters: private void gvHL7_DoubleClick(object sender, EventArgs e){ . . . } However, I want to use the .Point property, and EventArgs doesn't have that property. I know that DevExpress.XtraGrid.Views.Grid.GridMenuEventArgs does, but it's saying that's an invalid casting. What type should I cast my EventArgs instance to if I wish to access the .Point property? Edit: The double click function I'm working with is provided by devexpress for their grids.

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  • Differentiate generic methods by type parameters only using reflection?

    - by Brian Vallelunga
    I'm trying to use reflection to get a specific MethodInfo of a class, but am unsure how to differentiate between the two following methods: public class Test { public IBar<T1> Foo<T1>(); public IBar<T1, T2> Foo<T1, T2>(); } How can I get a reference to the different Foo methods, assuming I know the number of type parameters? Just calling typeof(Test).GetMethod("Foo") will throw an exception that the method name is ambiguous and there aren't a differing number of parameters to check.

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  • which lightweight SQL Server type could I use on my Dev machine for a C# VS2010 project?

    - by Greg
    Hi, Which lightweight SQL Server type could I use on my Dev machine for a C# VS2010 project? (e.g. sql server express, sql server ce, full version etc). That is, I'm running on a VMWare fusion instance on my MacBook, and just want something to develop against for a C# VS2010 project. I'm planning on having a simple database (not many tables) but will use Entity Framework. I haven't used SQL Server before so a quick pointer re what is the best database admin interface/app to use for the version you recommend (e.g. to create database, tables etc).

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  • Cannot implicitly convert type ... to ... problem

    - by Younes
    I have this code: public static IEnumerable<dcCustomer> searchCustomer(string Companyname) { TestdbDataContext db = new TestdbDataContext(); IEnumerable<dcCustomer> myCustomerList = (from Customer res in db.Customers where res.CompanyName == Companyname select res); return myCustomerList; } And whatever i try i keep getting the convert error. Error 1 Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<ConnectionWeb.Customer>' to 'System.Collections.Generic.IEnumerable<ConnectionWeb.DAL.dcCustomer>'. An explicit conversion exists (are you missing a cast?) \\srv01\home$\Z****\Visual Studio 2008\Projects\ConnectionWeb\ConnectionWeb\DAL\dcCustomer.cs 63 20 ConnectionWeb I want to try get myCustomerList to keep the values in an enumerator and return it.

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  • What tricks can be used to type and edit code faster?

    - by Thomas
    As Jeff Atwood noted, we are typists first, programmers second. Fast typing and editing may not be essential to be a good programmer, but it certainly helps. I noticed that I consciously and subconsciously use various tricks to get my intent across to the computer as fast as possible. What tricks can be used to type and edit code faster? I'm hoping to collect a nice list here that we can all learn from, so that we can be ever so slightly more productive. One trick per answer please! (This is not about typing speed in general. There are other questions about that. It's also not about general answers like "learn your editor's shortcut keys". Think of this topic as micro-optimizations for specific cases. See my own answers for examples of what I mean.)

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  • Styling the selection color of an input type=text, possible?

    - by Tommy
    Having an input <input type="text" id="myTest" value="bla bla bla"/> and doing this (using jQuery) $('#myTest').select(); causes "bla bla bla" to be selected with default dark blue selection color. Now, is there any way I can change this color using css? css3 can change selection using for instance ::-moz-selection { background: #ffb7b7; } but this only works on text in other elements, not in html inputs. Any ideas? /T

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  • How to process <input type="file" name="test1[f]" /> in PHP?

    - by user198729
    var_dump($_FILES) gives the following: array 'test1' => array 'name' => array 'f' => string 'ntuser.dat.LOG' (length=14) 'type' => array 'f' => string 'application/octet-stream' (length=24) 'tmp_name' => array 'f' => string 'D:\wamp\tmp\php223.tmp' (length=22) 'error' => array 'f' => int 0 'size' => array 'f' => int 0 Why is http designed this way?How can I get the file by $_FILES['test1']['f']?

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  • Programatically find out a file type by looking its binary content. Possible?

    - by daemonkid
    I have a c# component that will recieve a file of the following types .doc, .pdf, .xls, .rtf These will be sent by the calling siebel legacy app as a filestream. So... [LegacyApp] {Binary file stream} [Component] The legacy app is a black box that cant be modified to tell the component what file type (doc,pdf,xls) it is sending. The component needs to read this binary stream and create a file on the filesystem with the right extension. Any ideas? Thanks for your time.

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  • Is there a module that implements an efficient array type in Erlang?

    - by dsmith
    I have been looking for an array type with the following characteristics in Erlang. append(vector(), term()) O(1) nth(Idx, vector()) O(1) set(Idx, vector(), term()) O(1) insert(Idx, vector(), term()) O(N) remove(Idx, vector()) O(N) I normally use a tuple for this purpose, but the performance characteristics are not what I would want for large N. My testing shows the following performance characteristics... erlang:append_element/2 O(N). erlang:setelement/3 O(N). I have started on a module based on the clojure.lang.PersistentVector implementation, but if it's already been done I won't reinvent the wheel.

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  • Sql: simultaneous aggregate from two tables

    - by Ash
    I have two tables: a Files table, which includes the file type, and a File Properties table, which references the file table via a foreign key. Sample Files table: | id | name | type | --------------------- | 1 | file1 | zip | | 2 | file2 | zip | | 3 | file3 | zip | | 4 | file4 | jpg | And the Properties table: | file_id | property | ----------------------- | 1 | x | | 2 | x | I want to make a query, which shows the count of each file type, and how many files of that type have a property. So in the example, the result would be | type | filecount | prop count | ---------------------------------- | zip | 3 | 2 | | jpg | 1 | 0 | I could accomplish this by select f.type, (select count(id) from files where type = f.type), count(fp.id) from files as f, file_properties as fp where f.id = fp.file_id group by f.type; But this seems very suboptimal and is very slow. Any better way to do this?

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  • What's wrong with addlistener... how do i fire my event

    - by KoolKabin
    I am using the following functions to do my task. It works fine when cursor moves away from textbox but if i want to fire the same event from code say like next function i get error... function addEvent( obj, type, fn ) { if (obj.addEventListener) { obj.addEventListener( type, fn, false ); } else if (obj.attachEvent) { obj["e"+type+fn] = fn; obj[type+fn] = function() { obj"e"+type+fn; } obj.attachEvent( "on"+type, obj[type+fn] ); } else { obj["on"+type] = obj["e"+type+fn]; } } function addEventByName(ObjName, event, func){ MyEle = document.getElementsByName(ObjName); addEvent(MyEle[0], event, func); } addEventByName("txtBox", 'blur', function(){ alert('hello'); }); function fire(){ x = document.getElementsByName('txtBox')[0]; x.blur(); //gives error x.onblur(); //gives error }

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  • How do I use Declarations (type, inline, optimize) in Scheme?

    - by kunjaan
    How do I declare the types of the parameters in order to circumvent type checking? How do I optimize the speed to tell the compiler to run the function as fast as possible like (optimize speed (safety 0))? How do I make an inline function in Scheme? How do I use an unboxed representation of a data object? And finally are any of these important or necessary? Can I depend on my compiler to make these optimizations? thanks, kunjaan.

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  • What is wrong with this simple type definition? (Expecting one more argument to...)

    - by fluteflute
    basic.hs: areaCircle :: Floating -> Floating areaCircle r = pi * r * r Command: *Main> :l basic.hs [1 of 1] Compiling Main ( Sheet1.hs, interpreted ) Sheet1.hs:2:15: Expecting one more argument to `Floating' In the type signature for `areaCircle': areaCircle :: Floating -> Floating Failed, modules loaded: none. I see that areaCircle :: Floating a => a -> a loads as expected. Why is the above version not acceptable?

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  • How can the generic method called know the type of the generic return?

    - by Paulo Guedes
    I couldn't find a duplicate for this question for Java, although there are a lot of them for C#. I have this method: public <T> T getSomething() { // } According to the type of T, I will have a different return. For example: String a = getSomething(); int b = getSomething(); For a, my method will return a specific String. For b, it will return a specific int. And so on. It seems that this can be done with typeof() in C#. How can I achieve it in Java?

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  • Is it possible to specify a return type of "Derivative(of T)" for a MustOverride sub in VB.NET?

    - by Casey
    VB.NET 2008 .NET 3.5 I have two base classes that are MustInherit (partial). Let's call one class OrderBase and the other OrderItemBase. A specific type of order and order item would inherit from these classes. Let's call these WebOrder (inherits from OrderBase) and WebOrderItem (inherits from OrderItemBase). Now, in the grand scheme of things WebOrder is a composite class containing a WebOrderItem, like so: Public Class WebOrder Inherits OrderBase Public Property OrderItem() as WebOrderItem End Property End Class Public Class WebOrderItem Inherits OrderItemBase End Class In order to make sure any class that derives from OrderBase has the OrderItem property, I would like to do something like this in the OrderBase class: Public MustInherit Class OrderBase Public MustOverride Property OrderItem() as Derivative(Of OrderItemBase) End Class In other words, I want the derived class to be forced to contain a property that returns a derivative of OrderItemBase. Is this possible, or should I be using an entirely different approach?

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  • Which type of Rails model association should I use in this situation?

    - by jstayton
    I have two models/tables in my Rails application: discussions and comments. Each discussion has_many comments, and each comment belongs_to a discussion. My discussions table also includes a first_comment_id column and last_comment_id column for convenience and speed. I want to be able to call discussion.last_comment for the last comment model, but the following (in my discussion model) isn't working to make this happen: has_one :first_comment, :class_name => "Comment" has_one :last_comment, :class_name => "Comment" When I call discussion.last_comment, the following SQL is run: SELECT * FROM `comments` WHERE (`comments`.discussion_id = 1) LIMIT 1 It's using the discussions.id column to join against comments.discussion_id, when I want it to join discussions.last_comment_id against comments.id. Am I using the wrong type of association here? Thanks for your help!

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  • Problem with number/type of arguments passed to an overloaded c++ constructor wrapped with swig.

    - by MiKo
    I am trying to wrap a c++ class (let's call it "Spam") written by someone else with swig to expose it to Python. After solving several problems, I am able to import the module in python, but when I try to create an object of such class I obtain the following error: foo = Spam.Spam('abc',3) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "Spam.py", line 96, in __init__ this = _Spam.new_Spam(*args) NotImplementedError: Wrong number of arguments for overloaded function 'new_Spam'. Possible C/C++ prototypes are: Spam(unsigned char *,unsigned long,bool,unsigned int,SSTree::io_action,char const *) Spam(unsigned char *,unsigned long,bool,unsigned int,SSTree::io_action) Spam(unsigned char *,unsigned long,bool,unsigned int) Spam(unsigned char *,unsigned long,bool) Spam(unsigned char *,unsigned long) Googling around, I realized that the error is probably caused by the type of the arguments and not by the number (which is quite confusing), but I still cannot identify. I suspect the problem lies in passing a string as the first argument, but have no idea on how to fix it (keep in mind that I know almost no c/c++).

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