Each process in erlang has a process identifier (Pid) in this format <x.x.x>, x being a natural number. Below is an example of a Pid
<0.1252.0>
Pid can be used to send messages to the process using 'bang' (!), also Pid can be bounded to a variable, both are shown below
MyProcessId =...
Maybe
Maybe is a Functor containing a possibly-absent value:
instance Functor Maybe where
fmap f Nothing = Nothing
fmap f (Just x) = Just (f x)
Maybe's instance of Functor applies a function to a value wrapped in a Just. If the computation has previously failed (so the Maybe value is ...
An atomic type can be used to safely read and write to a memory location shared between two threads.
A Bad example that is likely to cause a data race:
#include <thread>
#include <iostream>
//function will add all values including and between 'a' and 'b' to 'result'
void add(int...
In PCRE, matched groups used for backreferences before a recursion are kept in the recursion. But after the recursion they all reset to what they were before entering it. In other words, matched groups in the recursion are all forgotten.
For example:
(?J)(?(DEFINE)(\g{a}(?<a>b)\g{a}))(?<a...
It's easier to implement some UDFs on the worksheet if full column references can be passed in as parameters. However, due to the explicit nature of coding, any loop involving these ranges may be processing hundreds of thousands of cells that are completely empty. This reduces your VBA project (and ...
PM2 lets you run your nodejs scripts forever. In the event that your application crashes, PM2 will also restart it for you.
Install PM2 globally to manager your nodejs instances
npm install pm2 -g
Navigate to the directory in which your nodejs script resides and run the following command each t...
The format of the struct statement is this:
struct [structure tag]
{
member definition;
member definition;
...
member definition;
} [one or more structure variables];
Example: declare the ThreeFloats structure:
typedef struct {
float x, y, z;
} ThreeFloats;
@inter...
Edit /etc/init/docker.conf and update the DOCKER_OPTS variable to the following:
DOCKER_OPTS='-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock'
Restart Docker deamon
service docker restart
Verify if Remote API is working
curl -X GET http://localhost:4243/images/json
Method references make excellent self-documenting code, and using method references with Streams makes complicated processes simple to read and understand. Consider the following code:
public interface Ordered {
default int getOrder(){
return 0;
}
}
public interface Valued<...
When working with existing model that is quite big and is being regenerated quite often in cases where abstraction needed it might be costly to manually go around redecorating model with interfaces. In such cases one might want to add some dynamic behavior to model generation.
Following example wil...
try (Realm realm = Realm.getDefaultInstance()) {
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
//whatever Transaction that has to be done
}
});
//No need to close realm in try-wit...
C# developers get a lot of null reference exceptions to deal with. F# developers don't because they have the Option type. An Option<> type (some prefer Maybe<> as a name) provides a Some and a None return type. It makes it explicit that a method may be about to return a null record.
For...
When using Access you can retrieve data using queries. These queries are built using Structured Query Language (SQL). Understanding SQL is important because it can help build better, more useful queries.
When creating queries in Access, you can switch to "SQL View". An example of a "...
Be aware that Microsoft Excel 2013 (and higher) uses Single Document
Interface (SDI) and that Excel 2010 (And below) uses Multiple Document
Interfaces (MDI).
This implies that for Excel 2013 (SDI), each workbook in a single instance of Excel contains its own ribbon UI:
Conversely for Excel...
The easiest method to bypass cache is to change the URL. This is used as a best practice when the URL contains a version or a checksum of the resource, e.g.
http://example.com/image.png?version=1
http://example.com/image.png?version=2
These two URLs will be cached separately, so even if …?versi...
The simple answer, when asking how to use threads in Python is: "Don't. Use processes, instead." The multiprocessing module lets you create processes with similar syntax to creating threads, but I prefer using their convenient Pool object.
Using the code that David Beazley first used to...
