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Multiprocessing - Pipe vs Queue
...nableQueue() as a bonus; JoinableQueue() accounts for tasks when queue.task_done() is called (it doesn't even know about the specific task, it just counts unfinished tasks in the queue), so that queue.join() knows the work is finished.
The code for each at bottom of this answer...
mpenning@mpennin...
How do i find out what all symbols are exported from a shared object?
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Addresses of names: 00037644
Entry Pt Ordn Name
0001FDA0 1 pcre_assign_jit_stack
000380B8 2 pcre_callout
00009030 3 pcre_compile
...
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Creating the Singleton design pattern in PHP5
...ctor so nobody else can instantiate it
*
*/
private function __construct()
{
}
}
To use:
$fact = UserFactory::Instance();
$fact2 = UserFactory::Instance();
$fact == $fact2;
But:
$fact = new UserFactory()
Throws an error.
See http://php.net/manual/en/language.variable...
enum - getting value of enum on string conversion
...;>> member.name
'red'
>>> member.value
1
You could add a __str__ method to your enum, if all you wanted was to provide a custom string representation:
class D(Enum):
def __str__(self):
return str(self.value)
x = 1
y = 2
Demo:
>>> from enum import E...
How can I implement a tree in Python?
...s easy to create. For example, a binary tree might be:
class Tree:
def __init__(self):
self.left = None
self.right = None
self.data = None
You can use it like this:
root = Tree()
root.data = "root"
root.left = Tree()
root.left.data = "left"
root.right = Tree()
root.right...
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...
Change auto increment starting number?
In MySQL, I have a table, and I want to set the auto_increment value to 5 instead of 1 . Is this possible and what query statement does this?
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How can I read a function's signature including default argument values?
...
@darth_coder: In Python2, getargspec raises TypeError if the input is not recognized as a Python function -- that is, a function implemented in Python. In CPython, Exception.__init__ is implemented in C, hence the TypeError. You'll...
Python nested functions variable scoping [duplicate]
...When I run your code I get this error:
UnboundLocalError: local variable '_total' referenced before assignment
This problem is caused by this line:
_total += PRICE_RANGES[key][0]
The documentation about Scopes and Namespaces says this:
A special quirk of Python is that – if no global st...
hidden symbol ... is referenced by DSO 剖析 - C/C++ - 清泛网 - 专注C/C++及内核技术
...因是符号(函数)未导出导致的，添加导出申明即可解决：__attribute__ ((visibility("default")) DSO 是动态共享对象，Linux报“hidden symbol ... is referenced by DSO”错误的原因是符号(函数)未导出导致的，添加导出申明即可解决：
__attribute__ (...