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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...
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...
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));
.....
Batch file to delete files older than N days
I am looking for a way to delete all files older than 7 days in a batch file. I've searched around the web, and found some examples with hundreds of lines of code, and others that required installing extra command line utilities to accomplish the task.
...
How are cookies passed in the HTTP protocol?
How are cookies passed in the HTTP protocol?
4 Answers
4
...
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,...
libpthread.so.0: error adding symbols: DSO missing from command line
When I'm compiling openvswitch-1.5.0, I've encountered the following compile error:
14 Answers
...
Hibernate JPA Sequence (non-Id)
...nly, your property mapping (.hbm.xml) would look like:
<property name="foo" generated="insert"/>
For properties generated on insert and update your property mapping (.hbm.xml) would look like:
<property name="foo" generated="always"/>
Unfortunately, I don't know JPA, so I don't kno...