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How can i tell if an object has a key value observer attached

... Put a try catch around your removeObserver call @try{ [someObject removeObserver:someObserver forKeyPath:somePath]; }@catch(id anException){ //do nothing, obviously it wasn't attached because an exception was thrown } ...
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Docker how to change repository name or rename image?

...host OS and Docker version? I suspect that something about your Docker installation is modifying the tag instruction. – Andy Feb 18 '16 at 2:41 27 ...
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Difference between Repository and Service Layer?

... bool Delete(int id); T Get(int id); bool SaveChanges(); } and call Get(id). Repository layer exposes basic CRUD operations. Service layer exposes business logic, which uses repository. Example service could look like: public interface IUserService { User GetByUserName(string userNa...
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PHP: How to send HTTP response code?

...-Code: 404', true, 404); I recommend the 2nd one. The first does work on all browsers I have tested, but some minor browsers or web crawlers may have a problem with a header line that only contains a colon. The header field name in the 2nd. variant is of course not standardized in any way and coul...
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Unable to install Maven on Windows: “JAVA_HOME is set to an invalid directory”

...ollowed the Maven tutorial to the letter but I still can't get Maven installed on Windows. 16 Answers ...
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Why does setTimeout() “break” for large millisecond delay values?

...s due to setTimeout using a 32 bit int to store the delay so the max value allowed would be 2147483647 if you try 2147483648 you get your problem occurring. I can only presume this is causing some form of internal exception in the JS Engine and causing the function to fire immediately rathe...
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What is the best way to trigger onchange event in react js

...s we wanted because React library overrides input value setter but we can call the function directly on the input as context. var nativeInputValueSetter = Object.getOwnPropertyDescriptor(window.HTMLInputElement.prototype, "value").set; nativeInputValueSetter.call(input, 'react 16 value'); var ev2 ...
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How do you default a new class to public when creating it in Visual Studio?

...1033. Visual Studio 2010 (10.0) and below: There is a zip file in there called Class.zip. Unpack this, edit the file to put in your public keyword then re-pack it (make sure you backup the original). After this, make sure VS rebuilds it's cache (which is just the zipfiles unzipped into directorie...
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Batch file to delete files older than N days

I am looking for a way to delete all files older than 7 days in a batch file. I've searched around the web, and found some examples with hundreds of lines of code, and others that required installing extra command line utilities to accomplish the task. ...
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filename and line number of python script

... Whether you use currentframe().f_back depends on whether you are using a function or not. Calling inspect directly: from inspect import currentframe, getframeinfo cf = currentframe() filename = getframeinfo(cf).filename print "This is line 5, python say...