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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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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...
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When is the @JsonProperty property used and what is it used for?

... As you know, this is all about serialize and desalinize an object. Suppose there is an object: public class Parameter { public String _name; public String _value; } The serialization of this object is: { "_name": "...", "_value": ".....
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Template function inside template class

... Write this: template <class T> template <class U> void MyClass<T>::foo() { /* ... */ } share | improve this answer | follow ...
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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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linux tee is not working with python?

I made a python script which communicates with a web server using an infinite loop. I want to log every communication data to a file and also monitor them from terminal at same time. so I used tee command like this. ...
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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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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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Best way to give a variable a default value (simulate Perl ||, ||= )

... In PHP 7 we finally have a way to do this elegantly. It is called the Null coalescing operator. You can use it like this: $name = $_GET['name'] ?? 'john doe'; This is equivalent to $name = isset($_GET['name']) ? $_GET['name']:'john doe'...
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Can I use require(“path”).join to safely concatenate urls?

... takes any number. So depending on what you're doing you may need to nest calls, eg.. url.resolve(url.resolve(SERVER_URL, pagePath), queryString) – Molomby Aug 23 '19 at 0:31 ...