In my projects I am using BroadcastReceivers as a callback from a long running thread (eg. notify the activity that a download was finished and send some response data from a Worker Thread so that the activity can display the appropriate message to the user..). To use BroadcastReceivers I have to be careful to register … Read more
Are delegates the same thing as callbacks? Or are they related somehow? Answer A “callback” is a term that refers to a coding design pattern, available in any language that has function pointers, or an analogue to function pointers (which is kinda what a delegate is) In this pattern, you pass a pointer to a … Read more
This question already has answers here: How to access the correct `this` inside a callback (13 answers) Closed 5 months ago. I’m having some trouble with plain old JavaScript (no frameworks) in referencing my object in a callback function. function foo(id) { this.dom = document.getElementById(id); this.bar = 5; var self = this; this.dom.addEventListener(“click”, self.onclick, false); … Read more
This question already has answers here: How to use class methods as callbacks (4 answers) Closed 7 days ago. How can I dynamically invoke a class method in PHP? The class method is not static. It appears that call_user_func(…) only works with static functions? Thanks. Answer It works both ways – you need to use … Read more
I have a C library that needs a callback function to be registered to customize some processing. Type of the callback function is int a(int *, int *). I am writing C++ code similar to the following and try to register a C++ class function as the callback function: class A { public: A(); ~A(); … Read more
While developing a camera app I’ve encountered an exception that only happened when I switch to other app (onPause() for my app). 01-15 17:22:15.017: E/AndroidRuntime(14336): FATAL EXCEPTION: main 01-15 17:22:15.017: E/AndroidRuntime(14336): java.lang.RuntimeException: Method called after release() 01-15 17:22:15.017: E/AndroidRuntime(14336): at android.hardware.Camera.setPreviewDisplay(Native Method) 01-15 17:22:15.017: E/AndroidRuntime(14336): at android.hardware.Camera.setPreviewDisplay(Camera.java:357) 01-15 17:22:15.017: E/AndroidRuntime(14336): at com.sora.cbir.yuki.image.leaf.CameraPreview.surfaceCreated(CameraPreview.java:32) 01-15 17:22:15.017: E/AndroidRuntime(14336): … Read more
I am working on ViewPager and using Fragment there I found setUserVisibleHint() called before onCreateView() in Fragment I am using Fragment from support library android.support.v4.app.Fragment Is this is a problem with Library ? How can I get rid of it ? EDIT I Override setUserVisibleHint() and not calling super to get rid of it. @Override … Read more
I’m new-ish to JavaScript. I understand many of the concepts of the language, I’ve been reading up on the prototype inheritance model, and I’m whetting my whistle with more and more interactive front-end stuff. It’s an interesting language, but I’m always a bit turned off by the callback spaghetti that is typical of many non-trivial … Read more
Let’s say I want to pass some extra data when assigning an event handler. Consider the following code: private void setup(string someData) { Object.assignHandler(evHandler); } public void evHandler(Object sender) { // need someData here!!! } How would I go about getting someData into my evHandler method? Answer private void setup(string someData) { Object.assignHandler((sender) => evHandler(sender,someData)); … Read more
I’m currently launching a programme using subprocess.Popen(cmd, shell=TRUE) I’m fairly new to Python, but it ‘feels’ like there ought to be some api that lets me do something similar to: subprocess.Popen(cmd, shell=TRUE, postexec_fn=function_to_call_on_exit) I am doing this so that function_to_call_on_exit can do something based on knowing that the cmd has exited (for example keeping count … Read more
