An Introduction to Dragon/Lessons/Variables

Variables

To create a new variable, you just need to determine the variable name & value. The value will determine the variable type and you can change the value to switch between the types using the same variable name.

Syntax:

	<Variable Name> = <Value>

.. tip::

The operator '=' is used here as an assignment operator and the same operator can be used in conditions, but for testing equality of expressions.

.. note::

The variable will contain the real value (not a reference). This means that once you change the variable value, the old value will be removed from memory (even if the variable contains a list or object).

Dynamic Typing

Dragon uses dynamic typing:

	x = "Hello"		// x is a string
	showln x  		// print list items
	x = 5			// x is a number (int)
	showln x 
	x = 1.2 		// x is a number (double)
	showln x 
	x = [1,2,3,4]	// x is a list
	showln x

Deep Copy

We can use the assignment operator '=' to copy variables. We can do that to copy values like strings & numbers, and even complete lists & objects! The assignment operator will do a complete duplication for us. This operation is called a deep copy.

	list = [1,2,3,"four","five"]
	list2 = list
	list = []
	show list	// print the first list - no items to print
	showln "********" 
	show list2	// print the second list - contains 5 items

Weakly Typed

Dragon is a weakly typed language. This means that the language can automatically convert between data types (like string & numbers) when that conversion makes sense.