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Why does Python code use len() function instead of a length method?
...
Strings do have a length method: __len__()
The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in ...
What does the caret operator (^) in Python do?
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It invokes the __xor__() or __rxor__() method of the object as needed, which for integer types does a bitwise exclusive-or.
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improv...
STL：accumulate与自定义数据类型 - C/C++ - 清泛网 - 专注C/C++及内核技术
...mulate()的原型为(文件取自DEV-C++编译器)：
template<typename _InputIterator, typename _Tp, typename _BinaryOperation>
_Tp accumulate(_InputIterator __first, _InputIterator __last, _Tp __init,
_BinaryOperation __binary_op)
{
// concept requirements
__glibcxx...
Best way to structure a tkinter application? [closed]
...or python 3
import tkinter as tk
class MainApplication(tk.Frame):
def __init__(self, parent, *args, **kwargs):
tk.Frame.__init__(self, parent, *args, **kwargs)
self.parent = parent
<create the rest of your GUI here>
if __name__ == "__main__":
root = tk.Tk()
...
Safe characters for friendly url [closed]
...igits, hyphen, period, underscore, and tilde."
ALPHA DIGIT "-" / "." / "_" / "~"
Note that RFC 3986 lists fewer reserved punctuation marks than the older RFC 2396.
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How to initialize all members of an array to the same value?
...e same value, without multiple copy-paste, you can use macros:
#define VAL_1X 42
#define VAL_2X VAL_1X, VAL_1X
#define VAL_4X VAL_2X, VAL_2X
#define VAL_8X VAL_4X, VAL_4X
#define VAL_16X VAL_8X, VAL_8X
#define VAL_32X VAL_16X, VAL_16X
#define VAL_64X VAL_32X, VAL_32X
i...
Define a lambda expression that raises an Exception
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There is more than one way to skin a Python:
y = lambda: (_ for _ in ()).throw(Exception('foobar'))
Lambdas accept statements. Since raise ex is a statement, you could write a general purpose raiser:
def raise_(ex):
raise ex
y = lambda: raise_(Exception('foobar'))
But if...
Why use def main()? [duplicate]
...tion could be:
import sys
def main(argv):
# My code here
pass
if __name__ == "__main__":
main(sys.argv)
This means you can call main() from other scripts (or interactive shell) passing custom parameters. This might be useful in unit tests, or when batch-processing. But remember that t...
List all the modules that are part of a python package?
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import email
package = email
for importer, modname, ispkg in pkgutil.iter_modules(package.__path__):
print "Found submodule %s (is a package: %s)" % (modname, ispkg)
How to import them too? You can just use __import__ as normal:
import pkgutil
# this is the package we are inspecting -- for...
How do I plot in real-time in a while loop using matplotlib?
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Did not work on Win64/Anaconda matplotlib.__version__ 1.5.0. An initial figure window opened, but did not display anything, it remained in a blocked state until I closed it
– isti_spl
Feb 4 '16 at 8:39
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