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Split string in Lua?
...
Doesn't work if string contains empty values, eg. 'foo,,bar'. You get {'foo','bar'} instead of {'foo', '', 'bar'}
– andras
Sep 19 '16 at 21:38
5
...
What is move semantics?
...to members
Sooner or later, you are going to write code like this:
class Foo
{
unique_ptr<Shape> member;
public:
Foo(unique_ptr<Shape>&& parameter)
: member(parameter) // error
{}
};
Basically, the compiler will complain that parameter is an lvalue. If you...
Validating parameters to a Bash script
... it as a commentar). i did "$#" to fix it. second, the regex also matches "foo123bar". i fixed it by doing ^[0-9]+$. you may also fix it by using grep's -x option
– Johannes Schaub - litb
Mar 31 '09 at 1:21
...
How to update PATH variable permanently from Windows command line?
...nvironment:PATH=...
...
> REM ## Query env-var:
> setenv.py PATH C:\foo
!!!Cannot access HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment:PATH due to: [WinError 5] Access is denied
!!!Cannot find HKEY_CURRENT_USER\Environment:PATH due to: [WinError 2] The syst...
“for” vs “each” in Ruby
...
Never ever use for it may cause almost untraceable bugs.
Don't be fooled, this is not about idiomatic code or style issues. Ruby's implementation of for has a serious flaw and should not be used.
Here is an example where for introduces a bug,
class Library
def initialize
@ary = []
...
What does the “at” (@) symbol do in Python?
...ons and class definitions
for more about decorators.
So, we see that
@foo
def bar():
pass
is semantically the same as:
def bar():
pass
bar = foo(bar)
They are not exactly the same because Python evaluates the foo expression (which could be a dotted lookup and a function call) befo...
how does array[100] = {0} set the entire array to 0?
...d the initialiser.
If your array is auto, then it is another story.
int foo(void)
{
char array[100] = {0};
...
}
In this case at every call of the function foo you will have a hidden memset.
The code above is equivalent to
int foo(void)
{
char array[100];
memset(array, 0, sizeof(array));
.....
Recursive Lock (Mutex) vs Non-Recursive Lock (Mutex)
...s not efficiency. Non-reentrant mutexes lead to better code.
Example: A::foo() acquires the lock. It then calls B::bar(). This worked fine when you wrote it. But sometime later someone changes B::bar() to call A::baz(), which also acquires the lock.
Well, if you don't have recursive mutexes,...
How do I get the object if it exists, or None if it does not exist?
... python is to wrap it in a try catch:
try:
go = SomeModel.objects.get(foo='bar')
except SomeModel.DoesNotExist:
go = None
What I did do, is to subclass models.Manager, create a safe_get like the code above and use that manager for my models. That way you can write: SomeModel.objects.safe_...
What does the “static” modifier after “import” mean?
... fields / method of a class instead of:
package test;
import org.example.Foo;
class A {
B b = Foo.B_INSTANCE;
}
You can write :
package test;
import static org.example.Foo.B_INSTANCE;
class A {
B b = B_INSTANCE;
}
It is useful if you are often used a constant from another class in yo...