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Why return NotImplemented instead of raising NotImplementedError
...
It's because __lt__() and related comparison methods are quite commonly used indirectly in list sorts and such. Sometimes the algorithm will choose to try another way or pick a default winner. Raising an exception would break out of the s...
PATH issue with pytest 'ImportError: No module named YadaYadaYada'
I used easy_install to install pytest on a mac and started writing tests for a project with a file structure likes so:
20 A...
std::vector performance regression when enabling C++11
...lts are identical:
(I am compiling your original code, with container.push_back(Item());)
$ g++ -std=c++11 -O3 -flto regr.cpp && perf stat -r 10 ./a.out
Performance counter stats for './a.out' (10 runs):
35.426793 task-clock # 0.986 CPUs utilized (...
Stop Mongoose from creating _id property for sub-document array items
...ose");
var subSchema = mongoose.Schema({
//your subschema content
},{ _id : false });
var schema = mongoose.Schema({
// schema content
subSchemaCollection : [subSchema]
});
var model = mongoose.model('tablename', schema);
...
Understanding the main method of python [duplicate]
...is almost unique to the language(*).
The semantics are a bit subtle. The __name__ identifier is bound to the name of any module as it's being imported. However, when a file is being executed then __name__ is set to "__main__" (the literal string: __main__).
This is almost always used to separate...
How do I detect whether a Python variable is a function?
...obj)
If this is for Python 3.x but before 3.2, check if the object has a __call__ attribute. You can do this with:
hasattr(obj, '__call__')
The oft-suggested types.FunctionTypes approach is not correct because it fails to cover many cases that you would presumably want it to pass, like with bui...
Checking images for similarity with OpenCV
...e the L2 relative error between images.
double errorL2 = norm( A, B, CV_L2 );
// Convert to a reasonable scale, since L2 error is summed across all pixels of the image.
double similarity = errorL2 / (double)( A.rows * A.cols );
return similarity;
}
else {
//Images have a differen...
Python dictionary: Get list of values for list of keys
...n list-comp:
Build list and throw exception if key not found: map(mydict.__getitem__, mykeys)
Build list with None if key not found: map(mydict.get, mykeys)
Alternatively, using operator.itemgetter can return a tuple:
from operator import itemgetter
myvalues = itemgetter(*mykeys)(mydict)
# use ...
How do I access the request object or any other variable in a form's clean() method?
... no reason to do it this way.
A much better way is to override the form's __init__ method to take an extra keyword argument, request. This stores the request in the form, where it's required, and from where you can access it in your clean method.
class MyForm(forms.Form):
def __init__(self, *...
Can “using” with more than one resource cause a resource leak?
...Drawing]System.Drawing.Font font4,
[2] bool CS$4$0000
)
IL_0000: nop
IL_0001: ldstr "Arial"
IL_0006: ldc.r4 10
IL_000b: newobj instance void [System.Drawing]System.Drawing.Font::.ctor(string, float32)
IL_0010: stloc.0
.try
{
IL_0011: ldstr "Arial"
...