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  • General question about Ruby Eigenclass/Singleton

    - by Dex
    module MyModule def my_method; 'hello'; end end class MyClass class << self include MyModule end end MyClass.my_method # => "hello I'm unsure why "include MyModule" needs to be in the eigenclass in order to be called using just MyClass. Why can't I go: X = MyClass.new X.my_method How is this type of pattern useful if I can't call it from an instance?

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  • How to make a link button visible after another button has been clicked in asp.net(vb) in button_c

    - by Parth
    How to make a link button visible after another button has been clicked in asp.net(vb) in button_click() it says error as "Object reference not set to an instance of an object." i've done this in my code Protected Sub InsertButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Dim receipt As LinkButton = FormView1.FindControl("LinkButton1") ' receipt.Enabled = "true" ' receipt.EnableTheming = "true" ' receipt.EnableViewState = "true" receipt.Visible = "true" End Sub

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  • Efficient way to build a MySQL update query in Python

    - by ensnare
    I have a class variable called attributes which lists the instance variables I want to update in a database: attributes = ['id', 'first_name', 'last_name', 'name', 'name_url', 'email', 'password', 'password_salt', 'picture_id'] Each of the class attributes are updated upon instantiation. I would like to loop through each of the attributes and build a MySQL update query in the form of: UPDATE members SET id = self._id, first_name = self._first name ... Thanks.

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  • unix process id

    - by swathi
    how to a Write a script that runs a 5 instances of a child process in the background (at a gap of 5 seconds) and do a continuous check to see if any of the child process is completed it starts another instance of the same process till the child process has executed 20 instances.

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  • Are reference attributes destroyed when class is destroyed in C++?

    - by Genba
    Suppose I have a C++ class with an attribute that is a reference: class ClassB { ClassA &ref; public: ClassB(ClassA &_ref); } Of course, the constructor is defined this way: ClassB::ClassB(ClassA &_ref) : ref(_ref) { /* ... */ } My question is: When an instance of class 'ClassB' is destroyed, is the object referenced by 'ClassB::ref' also destroyed?

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  • Set PdfPTable columns width iText

    - by Mr CooL
    I've a PdfPTable created in my Java program, Is there any way to actually set the width of specific column for the PdfPTable????? For instance, First column to be 5% width, second column to be 20% and etc. Urgent help please if anyone knows the way. Thanks in advance.

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  • Not sure what happens to my apps objects when using NSURLSession in background - what state is my app in?

    - by Avner Barr
    More of a general question - I don't understand the workings of NSURLSession when using it in "background session mode". I will supply some simple contrived example code. I have a database which holds objects - such that portions of this data can be uploaded to a remote server. It is important to know which data/objects were uploaded in order to accurately display information to the user. It is also important to be able to upload to the server in a background task because the app can be killed at any point. for instance a simple profile picture object: @interface ProfilePicture : NSObject @property int userId; @property UIImage *profilePicture; @property BOOL successfullyUploaded; // we want to know if the image was uploaded to out server - this could also be a property that is queryable but lets assume this is attached to this object @end Now Lets say I want to upload the profile picture to a remote server - I could do something like: @implementation ProfilePictureUploader -(void)uploadProfilePicture:(ProfilePicture *)profilePicture completion:(void(^)(BOOL successInUploading))completion { NSUrlSession *uploadImageSession = ..... // code to setup uploading the image - and calling the completion handler; [uploadImageSession resume]; } @end Now somewhere else in my code I want to upload the profile picture - and if it was successful update the UI and the database that this action happened: ProfilePicture *aNewProfilePicture = ...; aNewProfilePicture.profilePicture = aImage; aNewProfilePicture.userId = 123; aNewProfilePicture.successfullyUploaded = NO; // write the change to disk [MyDatabase write:aNewProfilePicture]; // upload the image to the server ProfilePictureUploader *uploader = [ProfilePictureUploader ....]; [uploader uploadProfilePicture:aNewProfilePicture completion:^(BOOL successInUploading) { if (successInUploading) { // persist the change to my db. aNewProfilePicture.successfullyUploaded = YES; [Mydase update:aNewProfilePicture]; // persist the change } }]; Now obviously if my app is running then this "ProfilePicture" object is successfully uploaded and all is well - the database object has its own internal workings with data structures/caches and what not. All callbacks that may exist are maintained and the app state is straightforward. But I'm not clear what happens if the app "dies" at some point during the upload. It seems that any callbacks/notifications are dead. According to the API documentation- the uploading is handled by a separate process. Therefor the upload will continue and my app will be awakened at some point in the future to handle completion. But the object "aNewProfilePicture" is non existant at that point and all callbacks/objects are gone. I don't understand what context exists at this point. How am I supposed to ensure consistency in my DB and UI (For instance update the "successfullyUploaded" property for that user)? Do I need to re-work everything touching the DB or UI to correspond with the new API and work in a context free environment?

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  • how do I use mod_rewrite for just one file?

    - by Angela
    I want to use mod-rewrite for just one file instance: www.domain.com/contact to pull from www.domain.com/contact.php I used a rewrite rule for all files that look like a directory to do this initially but it messed up some diretory redirects I created so in the short-term, I'd rather just do it for a specific file. Thanks.

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  • How to check if a BOOL is null?

    - by Sheehan Alam
    Is there a way I can check to see if a value is NULL/Nil before assigning it to a BOOL? For example, I have a value in a NSDictionary that can be either TRUE/FALSE/NULL mySTUser.current_user_following = [[results objectForKey:@"current_user_following"]boolValue]; When the value is NULL I get the following error *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSNull boolValue]: unrecognized selector sent to instance I would like to be able to handle the NULL case.

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  • Using a model to represent the overall state of a view

    - by James P.
    Is there a standard practise for representing the state of a user interface that is not linked to a single Component? For example, a Swing interface could have a series of tabs with a constraint that a single tab should only be displayed once per a given entity type (this could be represented as a HashSet). Or a message could give the result of the last operation carried out. Or a JPanel could be linked to a single entity instance for editing purposes.

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  • error prepareForSegue between a viewController and a tableViewController

    - by beta
    -(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { if ([segue.identifier isEqualToString:@"My_TableView"]) { MyTableViewController *destViewController = segue.destinationViewController; destViewController.data = data; } } Hi, I have a problem doing a segue (modal) between a ViewController to a TableViewController. The name of the segue between the ViewController and the NavigationController is "My_TableView". Compiler gives me this error: unrecognized selector sent to instance 0x9275b50 what's the problem?

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  • Method parameters confusion

    - by elec
    Often time methods take more than 3 parameters which are all of the same type, eg. void mymethod (String param1, String param2, String param3) then it's very easy for the client to mix up the parameters orders, for instance inverting param1 and param2: mymethod (param2, param1, param3); ...which can be the cause of much time spent debugging what should be a trivial matter. Any tips on how to avoid this sort of mistake (apart from unit tests) ?

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  • How to reference a class that implements certain interface?

    - by vikp
    Hi, I have an interface for logging the exceptions, i.e. IExceptionLogger. This interface has 3 implementations: DBExceptionLogger, XMLExceptionLogger, CSVExceptionLogger. I have an application that will make a use of DBExceptionLogger. The application references only IExceptionLogger. How do I create an instance of DBExceptionLogger within the application. I can't reference the DBExceptionLogger directly since it will break the purpose of having IExceptionLogger interface. Thanks

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  • How to get MS Word templates directory for another user?

    - by Steve
    I'm using the following code to get the path where Word stores its templates: WordTemplatePath:=WordApp.Options.DefaultFilePath[$00000002]; The problem is that this returns the path for the actual, logged-in user. Is there a way to get the path for another user of the same Windows instance? I need it so my installer program can install the templates used by my program for other users as well.

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  • JNI - native method with ByteBuffer parameter

    - by Ajan
    I've got a method: public native void doSomething(ByteBuffer in, ByteBuffer out); Generated by javah C/C++ header of this method is: JNIEXPORT void JNICALL Java__MyClass_doSomething (JNIEnv *, jobject, jobject, jobject, jint, jint); How can I get a data array from jobject (that is a ByteBuffer instance) ?

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