Alchemy Data Types

This section describes the data types available for use in a Alchemy script. A brief summary of each data type is given below.

Data Types

Type	Description	Examples
Array	A data structure consisting of a number of elements that are accessed by specifying an index.	$name = ["US", "United States"]
Boolean	A boolean can be one of three values: true, false or null.	$boolean_variable = true $access_allowed = false
Column	A data column within a shapefile table. A trailing question mark ('?') indicates that one or more cells in the column may contain a null value.	%id_type %roads3?
Hash Table	A hash table is a one-to-one unique mapping between a key-value pair. A value may be retrieved by specifying the corresponding key.	$hashTbl = { "GB" : "Great Britain", "NZ" : "New Zealand", "US" : "United States" }
Number	Floating point and integer numbers are supported; these may be signed or unsigned.	100 1.4142 -3.1416
String	Strings are a sequence of symbols (letters, numbers and some punctuation). Strings must be surrounded by double quotation marks (" ").	"Alchemy" "1-2-3 go!"
Variable	Variable names must begin with a dollar sign ($) immediately followed by a letter. The remainder of the name may contain letters (A - Z, a - z), numbers (0 - 9) and underscores (_).	$variable1 $terminal_velocity