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Parse config files, environment, and command-line arguments, to get a single collection of options
...d-line argument parsing ( argparse ). I want to write a program that does all those, and also:
11 Answers
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How can I add reflection to a C++ application?
...rate the data about each field(plus the field itself). This macro will be called like this:
REFLECTABLE
(
(const char *) name,
(int) age
)
So using Boost.PP we iterate over each argument and generate the data like this:
// A helper metafunction for adding const to a type
template<clas...
Code Golf: Lasers
...is sitting on top of now. Since the laser emitter is to be treated like a wall, set this to be a wall to begin with.
if (tr/v<^/>v</) {
my $o;
$o .= "\n" while s/.$/$o .= $&, ""/meg;
tr,/\\,\\/, for $o, $s;
$_ = $o;
}
If the laser beam is pointing any way except right, rotate...
What new capabilities do user-defined literals add to C++?
C++11 introduces user-defined literals which will allow the introduction of new literal syntax based on existing literals ( int , hex , string , float ) so that any type will be able to have a literal presentation.
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namedtuple and default values for optional keyword arguments
...lds)
>>> Node()
Node(val=None, left=None, right=None)
Order
In all versions of Python, if you set fewer default values than exist in the namedtuple, the defaults are applied to the rightmost parameters. This allows you to keep some arguments as required arguments.
>>> Node.__ne...
super() raises “TypeError: must be type, not classobj” for new-style class
...pe(OldStyle()) is the instance type, which does inherit from object. Basically, an old-style class just creates objects of type instance (whereas a new-style class creates objects whose type is the class itself). This is probably why the instance OldStyle() is an object: its type() inherits from ob...
How do I check if a string is a number (float)?
...r.
I'm not sure that anything much could be faster than the above. It calls the function and returns. Try/Catch doesn't introduce much overhead because the most common exception is caught without an extensive search of stack frames.
The issue is that any numeric conversion function has two kin...
Count character occurrences in a string in C++
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Small note, but the return type is typically signed. For some reason std::count returns type iterator_traits<InputIt>::difference_type, which for most standard containers is std::ptrdiff_t, not std::size_t.
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How to determine the version of the C++ standard used by the compiler?
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By my knowledge there is no overall way to do this. If you look at the headers of cross platform/multiple compiler supporting libraries you'll always find a lot of defines that use compiler specific constructs to determine such things:
/*Define Microsoft V...
Is there a TRY CATCH command in Bash
... writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way.
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