Brightsign BrightScript 2 Reference Guide Manual de usuario descargar pdf (Pagina 7)

Expressions, Variables, and Types

Identifiers

Identifiers (names of variables, functions, labels, or object member functions or interfaces

(appear after a “.”)) have the following rules.

 must start with an alphabetic character (a – z)

 may consist of alphabetic characters, numbers, or the symbol “_” (underscore)

 are not case sensitive

 may be of any length

 may not use a “reserved word” as the name (see appendix for list of reserved

words).

 if a variable: may end with an optional type designator character ($ for string, %

for integer, ! for float, # for double) (functions do not support this).

For example:

boy5

super_man$

Types

BrightScript uses dynamic typing. This means that every value also has a type

determined at run time. However, BrightScript also supports declared types. This

means that a variable can be made to always contain a value of a specific type. If a value

is assigned to a variable (which has a specific type), the type of the value assigned will be

converted to the variables type, if possible. If not possible, a runtime error will result.

The following types are supported in BrightScript:

 Boolean – either true or false

 Integer– 32 bit signed integer number

 Float – the smallest floating point number format supported by the hardware or

software

 Double - the largest floating point number format supported by the hardware or

software. Note that although BrightScript supports Double, Roku Objects do not.

 String. – a sequence of ASCII characters. Currently strings are ASCII, not UTF-

 Object – a reference to a Roku Object (native component). Note that if you use

the “type()” function, you will not get “rotOBJECT”. Instead you will get the

type of object. E.g.: “roList”, “roVideoPlayer”, etc. Also note that there is no

special type for “intrinsic” BrightScript objects. BrightScript objects are all built

on the Roku Object type “roAssociatiaveArray”.

 Interface- An interface in a Roku Object. If a “dot operator” is used on an

interface type, the member must be static (since there is no object context).

 Invalid – the type invalid has only one value – invalid. It is returned in various

cases, for example, when indexing an array that has never been set.

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Brightsign BrightScript 2 Reference Guide Manual de usuario Pagina 7