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How to check if the string is empty?
... the fact that empty sequences are false.
So you should use:
if not some_string:
or:
if some_string:
Just to clarify, sequences are evaluated to False or True in a Boolean context if they are empty or not. They are not equal to False or True.
...
Python multiprocessing PicklingError: Can't pickle
...as mp
class Foo():
@staticmethod
def work(self):
pass
if __name__ == '__main__':
pool = mp.Pool()
foo = Foo()
pool.apply_async(foo.work)
pool.close()
pool.join()
yields an error almost identical to the one you posted:
Exception in thread Thread-2:
Tracebac...
How do I print to the debug output window in a Win32 app?
... either maps to OutputDebugStringA(char const*) or OutputDebugStringW(wchar_t const*). In the later case you will have to supply a wide character string to the function. To create a wide character literal you can use the L prefix:
OutputDebugStringW(L"My output string.");
Normally you will use th...
How can I hash a password in Java?
...m recommended cost, used by default
*/
public static final int DEFAULT_COST = 16;
private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int SIZE = 128;
private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
private final Se...
while (1) vs. while(True) — Why is there a difference (in python 2 bytecode)?
...oes.
Here's 2.7:
>>> dis.dis('True == 1')
1 0 LOAD_GLOBAL 0 (True)
3 LOAD_CONST 1 (1)
6 COMPARE_OP 2 (==)
9 RETURN_VALUE
>>> dis.dis('True == 1')
1 0 LOAD_GLOBAL ...
How do I include a pipe | in my linux find -exec command?
...o use your top level shell to perform the piping like so:
find -name 'file_*' -follow -type f -exec zcat {} \; | agrep -dEOE 'grep'
In terms of efficiency this results costs one invocation of find, numerous invocations of zcat, and one invocation of agrep.
This would result in only a single agre...
Is there a way to access method arguments in Ruby?
...meters # => [[:req, :x], [:req, :y]]
You can use the special variable __method__ to get the name of the current method. So within a method the names of its parameters can be obtained via
args = method(__method__).parameters.map { |arg| arg[1].to_s }
You could then display the name and value ...
Assigning a variable NaN in python without numpy
...e 1, in <module>
File "C:\Python35\lib\fractions.py", line 146, in __new__
numerator)
ValueError: Invalid literal for Fraction: 'nan'
>>>
>>> Fraction(float('nan'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Python35\...
Find out time it took for a python script to complete execution
...test function"
L = []
for i in range(100):
L.append(i)
if __name__=='__main__':
from timeit import Timer
t = Timer("test()", "from __main__ import test")
print t.timeit()
Then to convert to minutes, you can simply divide by 60. If you want the script runtime in an easi...
Read-only and non-computed variable properties in Swift
...property which returns that property:
public class Clock {
private var _hours = 0
public var hours: UInt {
return _hours
}
}
But this can be achieved in a different, shorter way, as stated in the section "Access Control" of the "The Swift Programming Language" book:
public class Clo...