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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...t[AnyVal] because Int is a subtype of AnyVal. This means that you may provide an instance of List[Int] when a value of type List[AnyVal] is expected. This is really a very intuitive way for generics to work, but it turns out that it is unsound (breaks the type system) when used in the presence of ...
How to add a local repo and treat it as a remote repo
...
I am posting this answer to provide a script with explanations that covers three different scenarios of creating a local repo that has a local remote. You can run the entire script and it will create the test repos in your home folder (tested on windows git...
Just what is Java EE really? [closed]
...
Why can't the libraries function outside of the application server environment?
Actually they can. Most of the libraries can be directly used standalone (in Java SE) or included in a .war (practically that's nearly always Tomcat). Some parts of Java EE, like JP...
What are the best PHP input sanitizing functions?
...ons.
It's important to understand the difference between sanitizing and validating user data, escaping data for storage, and escaping data for presentation.
Sanitizing and Validating User Data
When users submit data, you need to make sure that they've provided something you expect.
Sanitization and ...
Covariance, Invariance and Contravariance explained in plain English?
...pes, other say it is about type conversion and others say it is used to decide whether a method is overwritten or overloaded.
All of the above.
At heart, these terms describe how the subtype relation is affected by type transformations. That is, if A and B are types, f is a type transformation, a...
Differences between ExpandoObject, DynamicObject and dynamic
..., the DLR performs late-bound calls to the instance's normal methods.
The IDynamicMetaObjectProvider interface allows a class to take control of its late-bound behavior.
When you use the dynamic keyword to interact with an IDynamicMetaObjectProvider implementation, the DLR calls the IDynamicMetaObj...
Java 8: performance of Streams vs Collections
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Stop using LinkedList for anything but heavy removing from the middle of the list using iterator.
Stop writing benchmarking code by hand, use JMH.
Proper benchmarks:
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@BenchmarkMode(Mode.AverageTime)
@OperationsPerInvocation(StreamVsVanilla.N)
publi...
Creating a daemon in Linux
...on (syslogd) is used for logging messages to files (debug, error,...).
Besides that, there are a few required steps to daemonize a process.
If I remember correctly these steps are:
fork off the parent process & let it terminate if forking was successful. -> Because the parent process ha...
.NET Global exception handler in console application
...ng you can work from perhaps:
using System;
class Program {
static void Main(string[] args) {
System.AppDomain.CurrentDomain.UnhandledException += UnhandledExceptionTrapper;
throw new Exception("Kaboom");
}
static void UnhandledExceptionTrapper(object sender, Unhandled...
What is the difference between graph search and tree search?
...p condition. open holds the nodes in memory, which are currently under consideration, the open list. Note that the following pseudo code is not correct in every aspect (2).
Tree Search
open <- []
next <- start
while next is not goal {
add all successors of next to open
next <- se...