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What is the difference between a static and a non-static initialization code block
...own, just like simple variable initializers) when the class is loaded (actually, when it's resolved, but that's a technicality).
Instance initializers are executed in the order defined when the class is instantiated, immediately before the constructor code is executed, immediately after the invocat...
Using python's eval() vs. ast.literal_eval()?
...
datamap = eval(raw_input('Provide some data here: ')) means that you actually evaluate the code before you deem it to be unsafe or not. It evaluates the code as soon as the function is called. See also the dangers of eval.
ast.literal_eval raises an exception if the input isn't a valid Python dat...
How do I create a constant in Python?
.... This is the closest equivalent to Java's final. However, it does not actually prevent reassignment:
from typing import Final
a: Final = 1
# Executes fine, but mypy will report an error if you run mypy on this:
a = 2
sha...
node.js require all files in a folder?
How do I require all files in a folder in node.js?
14 Answers
14
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How do I perform the SQL Join equivalent in MongoDB?
...rect. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <...
tinyxml XML解析库下载（tinyxml2.h 和 tinyxml2.cpp） - 源码下载 - 清泛...
...>
# include <cstdarg>
#endif
/*
TODO: intern strings instead of allocation.
*/
/*
gcc:
g++ -Wall -DDEBUG tinyxml2.cpp xmltest.cpp -o gccxmltest.exe
Formatting, Artistic Style:
AStyle.exe --style=1tbs --indent-switches --break-closing-brackets --indent-preproce...
Remove all occurrences of a value from a list?
...on over the filter+lambda; the former is more readable in addition to generally more efficient.
– habnabit
Jul 21 '09 at 4:28
17
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What does “hashable” mean in Python?
...y and a set member, because these data structures use the hash value internally.
All of Python’s immutable built-in objects are hashable, while no mutable containers (such as lists or dictionaries) are. Objects which are instances of user-defined classes are hashable by default; they all comp...
How do I run all Python unit tests in a directory?
...it test module is of the form test_*.py . I am attempting to make a file called all_test.py that will, you guessed it, run all files in the aforementioned test form and return the result. I have tried two methods so far; both have failed. I will show the two methods, and I hope someone out there ...
Why does ReSharper tell me “implicitly captured closure”?
... use.
The compiler generates a class for both lambda expressions and puts all variables in that class which are used in the lambda expressions.
So in my example g and i are held in the same class for execution of my delegates. If g is a heavy object with a lot of resources left behind, the garbage...