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When is assembly faster than C?
...igh part of 64 bit integer multiplication: A portable version using uint64_t for 32x32 => 64-bit multiplies fails to optimize on a 64-bit CPU, so you need intrinsics or __int128 for efficient code on 64-bit systems.
_umul128 on Windows 32 bits: MSVC doesn't always do a good job when multiplying ...
What are 'closures' in .NET?
...thod and the variable j
[CompilerGenerated]
private sealed class <>c__DisplayClass2
{
public <>c__DisplayClass2();
public void <fillFunc>b__0()
{
Console.Write("{0} ", this.j);
}
public int j;
}
for the function:
static void fillFunc(int count) {
...
Dynamic instantiation from string name of a class in dynamically imported module?
...
You can use getattr
getattr(module, class_name)
to access the class. More complete code:
module = __import__(module_name)
class_ = getattr(module, class_name)
instance = class_()
As mentioned below, we may use importlib
import importlib
module = importlib.imp...
What is the effect of extern “C” in C++?
...n it posted yet.
You'll very often see code in C headers like so:
#ifdef __cplusplus
extern "C" {
#endif
// all of your legacy C code here
#ifdef __cplusplus
}
#endif
What this accomplishes is that it allows you to use that C header file with your C++ code, because the macro "__cplusplus" will...
What happens to global and static variables in a shared library when it is dynamically linked?
...yntax similar to the function export/import syntax, i.e.:
#ifdef COMPILING_THE_DLL
#define MY_DLL_EXPORT extern "C" __declspec(dllexport)
#else
#define MY_DLL_EXPORT extern "C" __declspec(dllimport)
#endif
MY_DLL_EXPORT int my_global;
When you do that, the global variable is added to the list of...
Adding information to an exception?
....message +
' happens at %s' % arg1), sys.exc_info()[2]
bar('arg1')
Traceback (most recent call last):
File "test.py", line 16, in <module>
bar('arg1')
File "test.py", line 11, in bar
foo()
File "test.py", line 5, in foo
raise IOError('Stuff...
ASP.NET Identity's default Password Hasher - How does it work and is it secure?
...ashedPassword(string hashedPassword, string password)
{
byte[] _passwordHashBytes;
int _arrayLen = (SaltByteSize + HashByteSize) + 1;
if (hashedPassword == null)
{
return false;
}
if (password == null)
{
throw new...
C# Lazy Loaded Automatic Properties
... 4.0 Lazy<T> type to create this pattern
private Lazy<string> _someVariable =new Lazy<string>(SomeClass.IOnlyWantToCallYouOnce);
public string SomeVariable => _someVariable.Value;
This code will lazily calculate the value of _someVariable the first time the Value expression i...
What is the Python equivalent of static variables inside a function?
...e at the top instead of the bottom, you can create a decorator:
def static_vars(**kwargs):
def decorate(func):
for k in kwargs:
setattr(func, k, kwargs[k])
return func
return decorate
Then use the code like this:
@static_vars(counter=0)
def foo():
foo.coun...
What algorithm does Readability use for extracting text from URLs?
...spaper';
readSize = 'size-medium';
readMargin = 'margin-wide';
_readability_script = document.createElement('script');
_readability_script.type = 'text/javascript';
_readability_script.src = 'http://lab.arc90.com/experiments/readability/js/readability.js?x=' + (Math.random());
...