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Configuring Log4j Loggers Programmatically
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You can add/remove Appender programmatically to Log4j:
ConsoleAppender console = new ConsoleAppender(); //create appender
//configure the appender
String PATTERN = "%d [%p|%c|%C{1}] %m%n";
console.setLayout(new PatternLayout(PATTERN));
console.setThres...
Is a Python list guaranteed to have its elements stay in the order they are inserted in?
... what if I return a local list from a function and use that in the calling function. That is def fn_1(): lst = [] lst.append(1) lst.append(2) return lst and def fn_2(): print(fn_1()) Will the order be same ALWAYS irrespective of how many times or where ever I use fn_1() ?
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Pure virtual function with implementation
...se type can still define an implementation. A derived class can explicitly call the base class implementation (if access permissions allow it) by using a fully-scoped name (by calling A::f() in your example - if A::f() were public or protected). Something like:
class B : public A {
virtual vo...
SVN how to resolve new tree conflicts when file is added on two branches
...ming add upon merge' variety. Fixed expectations in r35341.
(This is also called "evil twins" in ClearCase by the way):
a file is created twice (here "added" twice) in two different branches, creating two different histories for two different elements, but with the same name.
The theoretical soluti...
Difference between 'new operator' and 'operator new'?
...y unusual unless you're writing something like your own container, you can call operator new directly, like:
char *x = static_cast<char *>(operator new(100));
It's also possible to overload operator new either globally, or for a specific class. IIRC, the signature is:
void *operator new(si...
Difference between JVM and HotSpot?
...For more on it, visit its site.
The current JVM provided by Sun/Oracle is called HotSpot because it seeks hot spots of use in the code (places where code is more intensively used) for "just-in-time" optimization. From the wikipedia, HotSpot, released as the "Java HotSpot Performance Engine" is a Ja...
Hidden Features of Java
...hen I first discovered it, never heard of it before.
ThreadLocals are typically not so widely known as a way to store per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interes...
What is __main__.py?
...ry or zipfile on the command line, and it executes the __main__.py automatically:
$ python my_program_dir
$ python my_program.zip
# Or, if the program is accessible as a module
$ python -m my_program
You'll have to decide for yourself whether your application could benefit from being executed lik...
STAThread and multithreading
...eading is a COM concept; if you're not using COM, and none of the APIs you call use COM "under the covers", then you don't need to worry about apartments.
If you do need to be aware of apartments, then the details can get a little complicated; a probably-oversimplified version is that COM objects t...
Difference between ref and out parameters in .NET [duplicate]
...out x); // OK
int y;
Foo(ref y); // Error: y should be initialized before calling the method
Ref parameters are for data that might be modified, out parameters are for data that's an additional output for the function (eg int.TryParse) that are already using the return value for something.
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