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Is it expensive to use try-catch blocks even if an exception is never thrown?
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try has almost no expense at all. Instead of doing the work of setting up the try at runtime, the code's metadata is structured at compile time such that when an exception is thrown, it now does a relatively expensive operation of walking up the stack an...
Create a pointer to two-dimensional array
...d T[10] are different types.
The following alternative doesn't work at all, because the element type of the array, when you view it as a one-dimensional array, is not uint8_t, but uint8_t[20]
uint8_t *matrix_ptr = l_matrix; // fail
The following is a good alternative
uint8_t (*matrix_ptr)[...
Suppressing deprecated warnings in Xcode
With all the SDKs floating around, it's handy to be able to build for multiple SDKs and platforms. However, bouncing from 3.2 to 3.0 and even occasionally 2.x, I frequently get deprecated warnings involving methods that have changed or been superseded:
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What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__?
... = "function-name";
appeared, where function-name is the name of the lexically-enclosing function. This name is the unadorned name of the function.
Note that it is not a macro and it has no special meaning during preprocessing.
__func__ was added to C++ in C++11, where it is specified as containi...
Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.
...ernel
def require_relative(path)
require File.join(File.dirname(caller[0]), path.to_str)
end
end
end
This allows you to use require_relative as you would in ruby 1.9.2 in ruby 1.8 and 1.9.1.
share
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In-memory size of a Python structure
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Yep. The "4 higher" actually mostly look like "rounding up to a multiple of 8" which I believe is correct for the way malloc behaves here. No idea why decimal gets so distorted (with pympler on 2.6, too).
– Alex Martelli
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How do I import the Django DoesNotExist exception?
...y of the model itself, in this case Answer.
Your problem is that you are calling the get method - which raises the exception - before it is passed to assertRaises. You need to separate the arguments from the callable, as described in the unittest documentation:
self.assertRaises(Answer.DoesNotExis...
Convert a String In C++ To Upper Case
...orm extremely badly with g++ 5.2 -O3, and Boost 1.58 (like 30x worse than calling glibc's toupper in a loop.) There's a dynamic_cast of the locale that doesn't get hoisted out of the per-char loop. See my answer. On the plus side, this may be properly UTF-8 aware, but the slowdown doesn't come fr...
Python: most idiomatic way to convert None to empty string?
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If you actually want your function to behave like the str() built-in, but return an empty string when the argument is None, do this:
def xstr(s):
if s is None:
return ''
return str(s)
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Resize fields in Django Admin
...awy to this in a form? I did not find a way to set the attrs attribute for all Textareas.
– Julian
Sep 5 '16 at 11:33
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