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  • How to share a variable between two classes?

    - by Altefquatre
    How would you share the same object between two other objects? For instance, I'd like something in that flavor: class A { private string foo_; // It could be any other class/struct too (Vector3, Matrix...) public A (string shared) { this.foo_ = shared; } public void Bar() { this.foo_ = "changed"; } } ... // inside main string str = "test"; A a = new A(str); Console.WriteLine(str); // "test" a.Bar(); Console.WriteLine(str); // I get "test" instead of "changed"... :( I read there is some ref/out stuff, but I couldn't get what I'm asking here. I could only apply some changes in the methods scope where I was using ref/out arguments... I also read we could use pointers, but is there no other way to do it?

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  • implmenting 1 to n mapping for ORM c++

    - by karan
    I am writing a project where i need to implment a stripped down version of an ORM solution in c++. I am struck in implmenting 1-n relationships for the same. For instance, if following are the classes: class A { } class B { std::list _a_list; } I have provided load/save menthods for loading/saving to the db. Now, if i take the case of B : Say , for the following workflow : 1 entry from _a_list is removed 1 entry from _a_list is modified 1 entry is added to _a_list Now, i need to update the db using something like "b.save()". So, what would be the best way to save the changes,i.e, identify the additions, deletions and updations to _a_list.

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  • Can anyone tell me what's wrong in this part of code

    - by Mobin
    string name = ((DateTimePicker)sender).Name.ToString(); name = name.Substring(0, name.Length - 1); name = name + "4"; TimeSpan duration = new TimeSpan(); duration = ((DateTimePicker)sender).Value - ((DateTimePicker)panel2.Controls[name]).Value; name = name.Substring(0, name.Length - 1); name = name + "6"; ((MaskedTextBox)panel2.Controls[name]).Text = duration.ToString(); On execution it gives me Object reference not set to instance of an object similar functionality is used on other places but I can't find out what I have to reinitialize here :$ The casting for datetimepicker is fine I have to get a name for the datetiempicker to identify the row it's on in my form and the picker before that to calculate their differences and then print that difference in a maskedtext box from the control whose name I make using names of two datetimepickers but when I access controls in the error line I get this message.

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  • Prolog term concatenation

    - by d0pe
    Hi, I'm trying to format a result from a program but getting an hard time. I wanted to give something like this as result: Res = do(paint(x) do(clean(a), do(repair(b) , initialState))) basically, I want to concatenate successive terms to initialState atom but, it doesn't work with atom_concat since the other terms to concatenate aren't atoms and also I wanted to add the ) everytime I pass through the "do" function. So it would be something like: Res = initialState. When do function was called, I would have a function like concatenateTerm(Pred, Res, Res). Pred beeing repair(b) for instance and obtain the result: res = do(repair(b), initialState). Is this possible to be done? Thanks

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  • Sqlalchemy layout with WSGI application

    - by TheDude
    I'm working on writing a small WSGI application using Bottle and SqlAlchemy and am confused on how the "layout" of my application should be in terms of SqlAlchemy. My confusion is with creating engines and sessions. My understanding is that I should only create one engine with the 'create_engine' method. Should I be creating an engine instance in the global namespace in some sort of singleton pattern and creating sessions based off of it? How have you done this in your projects? Any insight would be appreciated. The examples in the documentation dont seem to make this entirely clear (unless I'm missing something obvious). Any thoughts?

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  • How do I find the top N batters per year?

    - by Drew Stephens
    I'm playing around with the Lahman Baseball Database in a MySQL instance. I want to find the players who topped home runs (HR) for each year. The Batting table has the following (relevant parts) of its schema: +-----------+----------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+----------------------+------+-----+---------+-------+ | playerID | varchar(9) | NO | PRI | | | | yearID | smallint(4) unsigned | NO | PRI | 0 | | | HR | smallint(3) unsigned | YES | | NULL | | +-----------+----------------------+------+-----+---------+-------+ For each year, every player has an entry (between hundreds and 12k per year, going back to 1871). Getting the top N hitters for a single year is easy: SELECT playerID,yearID,HR FROM Batting WHERE yearID=2009 ORDER BY HR DESC LIMIT 3; +-----------+--------+------+ | playerID | yearID | HR | +-----------+--------+------+ | pujolal01 | 2009 | 47 | | fieldpr01 | 2009 | 46 | | howarry01 | 2009 | 45 | +-----------+--------+------+ But I'm interested in finding the top 3 from every year. I've found solutions like this, describing how to select the top from a category and I've tried to apply it to my problem, only to end up with a query that never returns: SELECT b.yearID, b.playerID, b.HR FROM Batting AS b LEFT JOIN Batting b2 ON (b.yearID=b2.yearID AND b.HR <= b2.HR) GROUP BY b.yearID HAVING COUNT(*) <= 3; Where have I gone wrong?

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  • How to support both DataContractSerializer and XMLSerializer for the same contract on the same host?

    - by Sly
    In our production environment, our WCF services are serialized with the XMLSerializer. To do so our service interfaces have the [XMLSerializerFormat] attribute. Now, we need to change to DataContractSerializer but we must stay compatible with our existing clients. Therefore, we have to expose each service with both serializers. We have one constraint: we don't want to redefine each contract interface twice, we have 50 services contract interfaces and we don't want to have IIncidentServiceXml IIncidentServiceDCS IEmployeeServiceXml IEmployeeServiceDCS IContractServiceXml IContractServiceDCS How can we do that? This is a description of what we have tried so far but I'm willing to try completely different approaches: We tried to create all the endpoints by code in our own ServiceHostFactory class. Basically we create each endpoint twice. The problem is that at runtime, WCF complains that the service has two endpoints with the same contact name but with different ContractDescription instances. The message says we should use different contract names or reuse the same ContractDescription instance.

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  • Having a base class function depend on its child class C#

    - by Junk Junk
    I have a Base class with a method that a child class will almost always override. However, instead of replacing the base class' method entirely, I would like for whatever is derived in the child class to be added to what is already in the base class. For Example: class BaseClass public string str() { var string = "Hello my name is" ; } class ChildClass : BaseClass public override string str(){ var string = "Sam"; } The point is that if I want to access the str() method by creating an instance of the ChildClass, the string will print out as "Hello, my name is Sam". I've been looking around and all I have been finding is that this should NOT happen, as the base class shouldn't even know that it is being inherited. So, if the design is false, how would I go about doing this? Keep in mind that there will be multiple child classes inheriting from BaseClass. Thank you

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  • vector<string> or vector<char *>?

    - by Aaron
    Question: What is the difference between: vector<string> and vector<char *>? How would I pass a value of data type: string to a function, that specifically accepts: const char *? For instance: vector<string> args(argv, argv + argc); vector<string>::iterator i; void foo (const char *); //*i I understand using vector<char *>: I'll have to copy the data, as well as the pointer Edit: Thanks for input!

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  • why does an event handler never gets called if its added within a loop on an ienumerable

    - by André Carvalho
    For instance: IEnumerable<MyType> list = someCollection.Select(i => new MyType(i)); foreach (var item in list) item.PropertyChanged += item_PropertyChanged; <-- this never gets called Bu if list is assigned like list = someCollection.Select(i => new MyType(i)).ToArray(); the event handler does get called.. Why? (i imagine it has something to do with the fact that a linq query is lazy, but the fact of looping through the result isn't enough??)

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  • What is the best way to convince management that virtualization isn't always appropriate in producti

    - by uncle brad
    I work for a small company with a .NET product that was acquired by a medium sized company with "big iron" products. Recently, the medium-sized part of the company acquired another small company with a similar .NET product and management went to have a look at their technology. They make heavy use of virtualization in their production environment and it's been decided that we will too. Our product was not designed to be run in a virtual environment, but some accommodations can be made. For instance; there are times when we're resource bound due to customer initiated processes. This initiation is "bursty" by nature, but the processing can be made asynchronous and throttled. This is something that would need to be done for scalability anyway. But there is other processing that we do that isn't so easily modified because we're resource bound for extended periods of time. How do I convince management that heavy use of virtualization is probably not appropriate for us?

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  • What is the point/purpose of Ruby EventMachine, Python Twisted, or JavaScript Node.js?

    - by CCw
    I don't understand what problem these frameworks solve. Are they replacements for a HTTP server like Apache HTTPD, Tomcat, Mongrel, etc? Or are they more? Why might I use them... some real world examples? I've seen endless examples of chat rooms and broadcast services, but don't see how this is any different than, for instance, setting up a Java program to open sockets and dispatch a thread for each request. I think I understand the non-blocking I/O, but I don't understand how that is any different than a multi-threaded web server.

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  • Expression.Call() to String.Equals() throws error

    - by Sam
    The following code: var constant = Expression.Constant("find me", typeof(string)); // memberExpression evaluates to a string var predicate = Expression.Call(memberExpression, "Equals", null, constant); is throwing the error More than one method 'Equals' on type 'System.String' is compatible with the supplied arguments. I'm guessing that's because there's Equals(Object) and Equals(String) - is there any way for me to specify which method I mean to use via the overload of Expression.Call() that takes an instance method name as a string? Or do I have to make a special case for calls to Equals() to take a MethodInfo instead?

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  • global std::unordered_map com server init problems

    - by PrettyFlower
    I want to have a static global std::unordered_map in the cpp of my entry point for my COM server. relevant header code: typedef unordered_map<HWND,IMyInterface*> MyMapType; relevant body: static MyMapType MyMap; void MyFunction(HWND hWnd, IMyInterface* pObj){ MyMap[HWND] = pObj; } HINSTANCE g_hInstModule = NULL; BOOL WINAPI DllMain ( __in HINSTANCE hInstDLL, __in DWORD fdwReason, __in LPVOID lpvReserved ) { if( fdwReason == DLL_PROCESS_ATTACH ) { g_hInstModule = hInstDLL; return true; } else if( fdwReason == DLL_PROCESS_DETACH ) { return true; } return false; } MyCoClass::MyCoClass() { DRM_Refcount = 1; } HRESULT STDMETHODCALLTYPE MyCoClass::InitMyCoClass() { CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); //replace with make window code MyFunction(hWnd,ISomeInterface); return S_OK; } The only way I can get this to work is be making a map_type pointer and creating an instance of map_type on the heap and pointing at it with the global pointer. :/ WHY?

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  • What are some programming questions (or mistakes) you get wrong only as you get better?

    - by BlueRaja
    In programming, as many professions, there are mistakes you'll make now that you may not have made as a beginner. For instance, consider pointers: In C++, is there any difference between arrays and pointers? The beginner will say yes, they are two completely different concepts, and treat them as such. The intermediate programmer (having learned that arrays are pointers internally) will tell you no, they are the same thing, and may miss some crucial bugs by interchanging them all willy-nilly. The expert, however, will again say they are different things (ex. see here or here). What other questions/mistakes are like this?

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  • Best practices for using Hg with Grails?

    - by leeand00
    What should I check in/not check in? Since many of the files are sometimes auto-generated I'm not entirely sure how to handle this using version control...does it have something to do with tags? For instance in ANT, I know not to check-in my target/bin directories...but Grails adds another level of confusion to this...since some of code is generated and some of it is not. (It may become clearer as I go...but it seems to be that there needs to be some way of being able to tell what was just generated and what was modified by a developer so that it needs to be placed in version control)

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  • Perl, treat string as binary byte array

    - by Mike
    In Perl, is it appropriate to use a string as a byte array containing 8-bit data? All the documentation I can find on this subject focuses on 7-bit strings. For instance, if I read some data from a binary file into $data my $data; open FILE, "<", $filepath; binmode FILE; read FILE $data 1024; and I want to get the first byte out, is substr($data,1,1) appropriate? (again, assuming it is 8-bit data) I come from a mostly C background, and I am used to passing a char pointer to a read() function. My problem might be that I don't understand what the underlying representation of a string is in Perl.

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  • Rails: How to produce 404 or redirect upon undesired url exploitation?

    - by Baby Diego
    I want to hide the urls for editing users and their profiles behind safer and meaningful urls. For instance, I want /user/13/edit to be /settings/account and /user/13/profile/edit to be /settings/profile. I managed to achieve that, but for that I had to load the user information from the current_user bit from the session. Like so: # users_controller def edit @user = current_user end # profiles_controller def edit @user = current_user @profile = @user.profile end But now, since I can't compare @user.id from the params with the current_user in the session, how can I stop the old urls (/user/13/edit and /user/13/profile/edit) from being exploitable? They always load the forms for the current user, so there's no harm done, but I'd be more comfortable if they just produced a 404 error or something. Thanks in advance.

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  • Installing XAMPP in Amazon EC2

    - by Woho87
    Hi! Can someone explain to me(not a rocket scientist) all the steps for installing XAMPP for a EC2 instance running Linux? And yes I have look the entire web and found nothing, except this "Deploying a lamp stack" and this "Starting Amazon EC2 with Mac OS X". I found the latter one more useful, but as a said I'm not a rocket scientist. I got stuck in to the latter link where I should edit the file .bash_profile with a text editor. I tried the "vi" in SSH, but why can't I open it on textEditor included in all Macs? Is there any easier way to setting up a XAMPP server for a linux server in EC2?

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  • Multiple Servers with identical services

    - by Jerry Bailey
    I have a dozen servers in different locations all running the same web service application but each going against their own SQL Server DB. I am writing a desktop application that consumes the web services. I want to present the user with a drop down of all servers in the network that are running the same wweb service application. Do I have to add a ServiceReference for each of the servers running the web service app and thereby having as many proxies as there are servers? Or can a define a single instance of the services and dynamically build a list of endpoints to select from a drop down?

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  • Hiding the console window in a system() call

    - by Justen
    Continuing from this question With each system call, the function constructs a set of parameters and sends them off to another program that is just console-based. Is there a way I can make it so that no console window pops up for each call? I've done a search but the ones that aren't a linker issue just aren't working for me. For instance, I tried the _execl call and System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; but they aren't working. The _execl will bring a console window up, scroll a bunch of stuff (from the program I called I guess), then close the my app and not even do what it was supposed to do. The System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; doesn't seem to execute what I want either because the output folder that should contain files, contains nothing. So I'm open for ideas.

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  • Program hangs when calling parseFrom for java implementation of protobuf

    - by cornerback84
    I have a message (say its called OuterMessage) message OuterMessage { optional int64 id = 1; optional InnerMessage inner = 2; } and an inner message message InnerMessage { optional string type = 1; optioanl int64 id = 2; } Now when I call parseFrom on OuterMessage like OuterMessage.parseFrom(buffer) the method never returns and nor does it throw any exception. But if I do InnerMessage.parseFrom(buffer) it returns an empty InnerMessage instance. I am serializing the message using protobuf-net. Any idea what might be causing the issue?

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  • When are dynamically loaded NIBs assigned frames and bounds data?

    - by thebossman
    In one of my UIViewControllers, I am calling initWithNibName:bundle: for several other UIViewControllers. I am grabbing the view property in each of those dynamically created controllers and placing them, one after the other, in my parent view. For instance, the y offset of viewControllerB should be equal to the height of viewControllerA. The y offset of viewControllerC should be equal to the height of viewControllerB, and so on. I am initalizing these nibs in viewDidLoad, yet none of them have any meaningful bounds or frame properties. The sizes and positions of each are all zero. Where is the 'correct' place to do this type of operation so that I can grab meaningful values from these properties?

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  • @@TRANCOUNT and a current connection

    - by AspOnMyNet
    Assume I connect to SQL server 2008 via SQL Server Management Studio ( SSMS ) and open new window W1 by clicking on New Query tab and write the following inside W1: BEGIN TRANSACTION; If I execute this statement 5 times, and then write (inside W1) SELECT @@TRANCOUNT; , then the value returned will be 5. But if I open another window W2 ( inside the same SSMS instance and thus on the same connection ) and write inside W2 SELECT @@TRANCOUNT; then value returned will be 0. @@TRANCOUNT variable returns the number of active transactions for the current connection. Both W1 and W2 windows were opened on the same connection, so shouldn’t ( according to the above quote ) in both W1 and W2 variable @@TRANCOUNT hold the same value? thanx

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  • Difference in techniques for setting a stubbed method's return value with Rhino Mocks

    - by CRice
    What is the main difference between these following two ways to give a method some fake implementation? I was using the second way fine in one test but in another test the behaviour can not be achieved unless I go with the first way. These are set up via: IMembershipService service = test.Stub<IMembershipService>(); so (the first), using (test.Record()) //test is MockRepository instance { service.GetUser("dummyName"); LastCall.Return(new LoginUser()); } vs (the second). service.Stub(r => r.GetUser("dummyName")).Return(new LoginUser()); Edit The problem is that the second technique returns null in the test, when I expect it to return a new LoginUser. The first technique behaves as expected by returning a new LoginUser. All other test code used in both cases is identical.

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