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Legality of COW std::string implementation in C++11
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It's not allowed, because as per the standard 21.4.1 p6, invalidation of iterators/references is only allowed for
— as an argument to any standard library function taking a reference
to non-const basic_string as an argument.
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Recursive Lock (Mutex) vs Non-Recursive Lock (Mutex)
POSIX allows mutexes to be recursive. That means the same thread can lock the same mutex twice and won't deadlock. Of course it also needs to unlock it twice, otherwise no other thread can obtain the mutex. Not all systems supporting pthreads also support recursive mutexes, but if they want to be P...
What really is a deque in STL?
I was looking at STL containers and trying to figure what they really are (i.e. the data structure used), and the deque stopped me: I thought at first that it was a double linked list, which would allow insertion and deletion from both ends in constant time, but I am troubled by the promise made ...
Why use Object.prototype.hasOwnProperty.call(myObj, prop) instead of myObj.hasOwnProperty(prop)?
...y reference.
And since we are at it, why do we define this function at all?
See above.
Is it
just a question of shortcuts and local caching of property access for
(slight) performance gains...
It may make it quicker in theory, as the [[Prototype]] chain doesn't have to be followed, ...
Clearing coverage highlighting in Eclipse
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Click the "Remove all Sessions" button in the toolbar of the "Coverage" view.
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Getting the name of the currently executing method
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Thread.currentThread().getStackTrace() will usually contain the method you’re calling it from but there are pitfalls (see Javadoc):
Some virtual machines may, under some circumstances, omit one or more stack frames from the stack trace. In the extreme case, a virtua...
Lambda function in list comprehensions
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The first one creates a single lambda function and calls it ten times.
The second one doesn't call the function. It creates 10 different lambda functions. It puts all of those in a list. To make it equivalent to the first you need:
[(lambda x: x*x)(x) for x in range(10)]
Or b...
Java JTable setting Column Width
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What happens if you call setMinWidth(400) on the last column instead of setPreferredWidth(400)?
In the JavaDoc for JTable, read the docs for doLayout() very carefully. Here are some choice bits:
When the method is called as a result of the ...
method of iterating over sqlalchemy model's defined columns?
...l exclude SA magic attributes, but will not exclude the relations. So basically it might load the dependencies, parents, children etc, which is definitely not desirable.
But it is actually much easier because if you inherit from Base, you have a __table__ attribute, so that you can do:
for c in Jo...
How to post data in PHP using file_get_contents?
...Sending an HTTP POST request using file_get_contents is not that hard, actually : as you guessed, you have to use the $context parameter.
There's an example given in the PHP manual, at this page : HTTP context options (quoting) :
$postdata = http_build_query(
array(
'var1' => 'some...