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When does invoking a member function on a null instance result in undefined behavior?

...) and (b) result in undefined behavior. It's always undefined behavior to call a member function through a null pointer. If the function is static, it's technically undefined as well, but there's some dispute. The first thing to understand is why it's undefined behavior to dereference a null poin...
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Complete Working Sample of the Gmail Three-Fragment Animation Scenario?

...at I'll refer to as "the Gmail three-fragment animation" scenario. Specifically, we want to start with two fragments, like this: ...
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Determining Referer in PHP

...s the most reliable and secure way to determine what page either sent, or called (via AJAX), the current page. I don't want to use the $_SERVER['HTTP_REFERER'] , because of the (lack of) reliability, and I need the page being called to only come from requests originating on my site. Edit: I am...
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Python call function within class

... Since these are member functions, call it as a member function on the instance, self. def isNear(self, p): self.distToPoint(p) ... share | improve t...
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Python argparse command line flags without arguments

...a look at http://docs.python.org/dev/library/argparse.html#action (specifically store_true and store_false) import argparse parser = argparse.ArgumentParser() parser.add_argument('-w', action='store_true') where action='store_true' implies default=False. Conversely, you could haveaction='store_...
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How to select an element by classname using jqLite?

... Essentially, and as-noted by @kevin-b: // find('#id') angular.element(document.querySelector('#id')) //find('.classname'), assumes you already have the starting elem to search from angular.element(elem.querySelector('.classname'))...
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Using git commit -a with vim

...rupt the commit when I quit vim? There are 2 ways: :cq or :cquit Delete all lines of the commit message, including comments, and then :wq Either way will give git an error code, so it will not proceed with the commit. This is particularly useful with git commit --amend. ...
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How can I obtain an 'unbalanced' grid of ggplots?

...RonGejman it's easy if you print the 3x2 matrix on screen: first column is all 1s, that's where the first plot lives, spanning the three rows; second column contains plots 2, 3, 4, each occupying one row. – baptiste Sep 30 '15 at 18:59 ...
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How to check if a given directory exists in Ruby

I am trying to write a script which automatically checks out or updates a Subversion URL based on whether a specified directory exists or not. ...
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count members with jsonpath?

... @mattb - if using Maven, do not add hamcrest-all as a dependancy, but use hamcrest-library: code.google.com/p/hamcrest/wiki/HamcrestDistributables – Adam Michalik Nov 3 '15 at 13:37 ...