/**

\page doc_global Globals

All global declarations share the same namespace so their names may not
conflict. This includes extended data types and built-in functions registered
by the host application. Also, all declarations are visible to all, e.g. a
function to be called does not have to be declared above the function that calls
it.

    <ul>
    <li>\ref doc_global_function
    <li>\ref doc_global_variable
    <li>\ref doc_global_class
    <li>\ref doc_global_interface
    <li>\ref doc_global_import
    <li>\ref doc_global_enums
    <li>\ref doc_global_typedef
    <li>\ref doc_global_funcdef
    </ul>




\section doc_global_function Functions

Global functions are declared normally, just as in C/C++. The function body must be defined, 
i.e. it is not possible to declare prototypes, nor is it necessary as the compiler can resolve 
the function names anyway.

For parameters sent by reference, i.e. with the <code>&amp;</code> modifier it is necessary to 
specify in which direction the value is passed, <code>in</code>, <code>out</code>, or <code>inout</code>, e.g. <code>&amp;out</code>. If no keyword 
is used, the compiler assumes the <code>inout</code> modifier. For parameters marked with <code>in</code>, the value is 
passed in to the function, and for parameters marked with <code>out</code> the value is returned from the function.

Parameters can also be declared as <code>const</code> which prohibits the alteration of their value. It is
good practice to declare variables that will not be changed as <code>const</code>,
because it makes for more readable code and the compiler is also able to take advantage 
of it some times. Especially for <code>const &amp;in</code> the compiler is many times able to avoid a copy of the value.

Note that although functions that return types by references can't be
declared by scripts you may still see functions like these if the host
application defines them. In that case the returned value may also
be used as the target in assignments.

<pre>
  int MyFunction(int a, int b)
  {
    return a + b;
  }
</pre>





\section doc_global_variable Variables

Global variables may be declared in the scripts, which will then be shared between 
all contexts accessing the script module.

The global variables may be initialized by simple expressions that do not require 
any functions to be called, i.e. the value can be evaluated at compile time.

Variables declared globally like this are accessible from all functions. The 
value of the variables are initialized at compile time and any changes are 
maintained between calls. If a global variable holds a memory resource, e.g. 
a string, its memory is released when the module is discarded or the script engine is reset.

<pre>
  int MyValue = 0;
  const uint Flag1 = 0x01;
</pre>

Variables of primitive types are initialized before variables of non-primitive types.
This allows class constructors to access other global variables already with their
correct initial value. The exception is if the other global variable also is of a 
non-primitive type, in which case there is no guarantee which variable is initialized 
first, which may lead to null-pointer exceptions being thrown during initialization.






\section doc_global_class Classes

In AngelScript the script writer may declare script classes. The syntax is
similar to that of C++ or Java.

With classes the script writer can declare new data types that hold groups
of variables and methods to manipulate them. The classes also supports inheritance
and polymorphism through \ref doc_global_interface "interfaces".

<pre>
  // The class declaration
  class MyClass
  {
    // The default constructor
    MyClass()
    {
      a = 0;
    }

    // A class method
    void DoSomething()
    {
      a *= 2;
    }

    // A class property
    int a;
  }
</pre>

\see \ref doc_script_class





\section doc_global_interface Interfaces

An interface works like a contract, the classes that implements an interface
are guaranteed to implement the methods declared in the interface. This allows
for the use of polymorphism in that a function can specify that it wants an
object handle to an object that implements a certain interface. The function
can then call the methods on this interface without having to know the
exact type of the object that it is working with.

<pre>
  // The interface declaration
  interface MyInterface
  {
    void DoSomething();
  }

  // A class that implements the interface MyInterface
  class MyClass : MyInterface
  {
    void DoSomething()
    {
      // Do something
    }
  }
</pre>

A class can implement multiple interfaces; Simply list all the interfaces
separated by a comma.





\section doc_global_import Imports

Sometimes it may be useful to load script modules dynamically without having to recompile 
the main script, but still let the modules interact with each other. In that case the script 
may import functions from another module. This declaration is written using the import 
keyword, followed by the function signature, and then specifying which module to import from.

This allows the script to be compiled using these imported functions, without them actually 
being available at compile time. The application can then bind the functions at a later time, 
and even unbind them again.

If a script is calling an imported function that has not yet been bound the script will be 
aborted with a script exception.

<pre>
  import void MyFunction(int a, int b) from "Another module";
</pre>





\section doc_global_enums Enums

Enums are a convenient way of registering a family of integer constants that may be used throughout the script 
as named literals instead of numeric constants. Using enums often help improve the readability of the code, as
the named literal normally explains what the intention is without the reader having to look up what a numeric value
means in the manual.

Even though enums list the valid values, you cannot rely on a variable of the enum type to only contain values
from the declared list. Always have a default action in case the variable holds an unexpected value.

The enum values are declared by listing them in an enum statement. Unless a specific value is given for an enum 
constant it will take the value of the previous constant + 1. The first constant will receive the value 0, 
unless otherwise specified.

<pre>
  enum MyEnum
  {
    eValue0,
    eValue2 = 2,
    eValue3,
    eValue200 = eValue2 * 100
  }
</pre>






\section doc_global_typedef Typedefs

Typedefs are used to define aliases for other types.

Currently a typedef can only be used to define an alias for primitive types, but a future version will have
more complete support for all kinds of types.

<pre>
  typedef float  real32;
  typedef double real64;
</pre>



\section doc_global_funcdef Funcdefs

Funcdefs are used to define a function signature that will be used to store pointers to 
functions with matching signatures. With this a function pointer can be created, which is 
able to store dynamic pointers that can be invoked at a later time as a normal function call.

<pre>
  // Define a function signature for the function pointer
  funcdef bool CALLBACK(int, int);
</pre>

\see \ref doc_datatypes_funcptr for more information on how to use this

*/
