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How to properly check if std::function is empty in C++11?
...'re not checking for an empty lambda, but whether the std::function has a callable target stored in it. The check is well-defined and works because of std::function::operator bool which allows for implicit conversion to bool in contexts where boolean values are required (such as the conditional expr...
Difference between Python datetime vs time modules
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the time module is principally for working with unix time stamps; expressed as a floating point number taken to be seconds since the unix epoch. the datetime module can support many of the same operations, but provides a more object oriented set of t...
Create objective-c class instance by name?
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id object = [[NSClassFromString(@"NameofClass") alloc] init];
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Checking from shell script if a directory contains files
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The solutions so far use ls. Here's an all bash solution:
#!/bin/bash
shopt -s nullglob dotglob # To include hidden files
files=(/some/dir/*)
if [ ${#files[@]} -gt 0 ]; then echo "huzzah"; fi
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See “real” commit date in github (hour/day)
...a <time> element with an iso value under its datetime attribute.
If all else fails, like it did for me, try inspecting the text.
Sample element:
<time datetime="2015-01-22T20:48:13Z" is="relative-time" title="Jan 22, 2015, 2:48 PM CST">7 days ago</time>
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How does IPython's magic %paste work?
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You actually can copy code to IPython directly: you may have to first disable auto-indentation by entering %autoindent.
– Eric O Lebigot
Jan 15 '13 at 3:51
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MySQL DISTINCT on a GROUP_CONCAT()
...d Jun 21 '10 at 9:47
Daniel Vassallo
301k6666 gold badges475475 silver badges424424 bronze badges
answered Jun 21 '10 at 9:41
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How to get a DOM Element from a JQuery Selector
...h:
$("table").get(0);
or more simply:
$("table")[0];
There isn't actually a lot you need this for however (in my experience). Take your checkbox example:
$(":checkbox").click(function() {
if ($(this).is(":checked")) {
// do stuff
}
});
is more "jquery'ish" and (imho) more concise. W...
What happens with constraints when a view is removed
...hen I do something like this, I save the constraints like this for a view called view1:
self.portraitConstraints = [NSMutableArray new];
for (NSLayoutConstraint *con in self.view.constraints) {
if (con.firstItem == self.view1 || con.secondItem == self.view1) {
[self.portraitConstraints a...
What is the most efficient way to store tags in a database?
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Actually I believe de-normalising the tags table might be a better way forward, depending on scale.
This way, the tags table simply has tagid, itemid, tagname.
You'll get duplicate tagnames, but it makes adding/removing/editing...