Language

The new lang.Closeable interface and ARM blocks

The new lang.Closeable interface and the io.streams classes being retrofitted to implement it may not seem very useful on the first glance, although they serve the purpose of supporting the so-called ARM blocks. These are a feature supported by XP Language and reuse the try keyword:

  try ($expression[, $expression[, ...]]) {
    // Statements
  }

XP language cheat sheet: Differences from PHP

Now that we know the basics about the XP language - how to write a "hello world" application, how to compile and run it, and after looking at the underlying type system, and have seen both is quite similar to PHP - let's explore the differences, the object and concatenation operators, changed foreach, array and map syntaxes, the removed function keyword, as well as the now syntactically supported annotations, chaining, enumerations, varargs, and finally, the finally block.

The XP language's type system

As promised in the first article of our XP language series, we will have a look at the type system. The XP language knows about the following types:

• Primitives - The following primitives exist: int, float, string and bool
  
• Reference types - Classes, interfaces and enums, e.g. lang.Object, util.log.Traceable and util.DateInterval
  
• Arrays - An array is a zero-based and continuously numbered list of any type, e.g. string[] or util.Date[].
  
• Maps - A map is a hashtable mapping string keys to any type, e.g. [:string] or [:lang.XPClass]
  
• The variable type - Marks a type that may either be a primitive or any reference type, declared with the keyword "var". The compiler will not be able to verify type correctness in this case and will warn about this - checks will be deferred until runtime.
  

First steps with the XP Language

The XP language is not completely different from the way PHP works, it keeps the flexibility and the general "look and feel" while adding syntactical support for features PHP doesn't support or doesn't support in all versions the XP Framework runs on.

Like in the XP framework, the entry point is always a class. In their most simple form, these classes have a static main() method. An example:

  public class HelloWorld {
    public static void main(string[] $args) {
      util.cmd.Console::writeLine('Hello World from ', self::class.getName(), '!');
    }
  }

Introducing: The next big thing

If you have recently updated your SVN checkout, you may have seen a line like the following flying by:

U    devel/xp/trunk/rfc/0052.rfc.txt

Stay tuned

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