Special Variable Syntax

4RPL supports special syntax for referencing global variables, vectors, lists, and tables.

<-* ->* -?* –* <-!* ->!* -?!* –!*

All of the variable commands can also be used followed by the * symbol in order to access global variables instead. Global variables do not belong to one single script, reading or writing to a global variable will modify the same exact value from any script.

Global variables belong to a map and can be accessed from within different CPACK's. For this reason it is recommended to stick to a unique naming convention to prevent collisions with other CPACK's.

Global variables may have the same names as local variables, there is no interference between them.

One example global variables may be used for is storing values which should always be the same across all units. That way it isn't necessary to send a message to each individual unit.

# --SomeScript--
true ->*disableMyCustomUnits

# --CustomUnit--
if (<-*disableMyCustomUnits)
    SetUnitDebugText(self "Disabled")
else
    SetUnitDebugText(self "")
    @Operate
endif

⇐ Index

Vectors contain up to 4 fields. These fields can be referenced with a suffix that implies the use of the vector

• .x .y .z .w (coordinates)
• .r .g .b .a (color)
• .0 .1 .2 .3 (index)

Simply place the suffix after the variable name for reading or writing. Suffixes are fungible.

V4(1 2 3 4) ->vector
traceallsp(<-vector.x <-vector.y)
42 ->vector.2
V3(255 0 0) ->red

A brief note on color values:

Color is represented by 4 values, each of the first 3 the intensity of one of the primary colors (Red, Green and Blue) and the 4th value the Alpha channel. Alpha values indicate transparency or opacity. All of these values are floating-point values ranging from 0 to 1, with higher values truncated to 1.

Example:

V4(1,1,1,1)

is white.

V4(1 0 0 1)

is red.

V4(0 1 0 1)

is green.

V4(0 0 1 1)

is blue.

Combining different values result in any other intermediate color.

Changing the 4th field to a lesser value would increase the transparency, until at 0 it would render the text invisible

⇐ Index

⇐ List Commands

Lists are collections of data. They are similar to arrays but they do not have a fixed length. They can have items added or removed. The elements in a list can be referenced using specific APIS, like GetListElement (and other List APIs). They can also be accessed using square bracket notation [<-index], which is a compact way of writing list-element getters/setters.

[<-index] can be written on its own and will translate to <-index GetListElementRPL, effectively getting the element at the given index from a list at the top of the stack. If the item on the stack is no list an error will be printed to the console.

However, if [<-index] is preceded by a variable setter, ->variable [<-index], it along with the variable setter will translate to <-variable <-index SetListElementRPL, effectively setting element number “index” of the variable to whichever value is on top of the stack. If variable is not a list, a warning will be printed to the console.

See also: coerce table to list

CreateList ->list
"abc" ->list[0]   
traceallsp(<-list[0])

⇐ Index

⇐ Table Commands

Tables are collection of named data. They are sometimes called dictionaries in other languages. They contain data made up of a string name (the key) and a value. A value can be quickly looked up by its name/key. Data in a table can be referenced with GetTableElement (and other Table APIs). Data can also be accessed using curly brace syntax {<-key}, which is a compact way of writing table-element getters/setters.

{<-key} can be written on its own and will translate to <-key GetTableElementRPL, effectively getting the element at the given key from a table at the top of the stack. If the item on the stack is not a table, an error will be printed to the console.

However, if {<-key} is preceded by a variable setter, ->variable {<-key}, it along with the variable setter will translate to <-variable <-key SetTableElementRPL, effectively setting the value of that key in the variable to whichever value is on top of the stack. If variable is not a table, a warning will be printed to the console.

CreateTable ->table
42 ->table{"SomeName"}
traceallsp(<-table{"SomeName"})

It is possible to iterate over the elements in a table by coercing the table into a list. The following shows two equivalent methods to extract data from a table. Method Two is slightly more efficient.

#Make sure some units are on the map when testing!
 
"Cannon"    V2(0.03 75) 
"Mortar"    V2(0.05 25) 
"Sniper"    V2(0.02 20) 
Table ->units 
 
# method One
 
Do (GetTablecount(<-units) 0)
	GetUnitsByType (<-units[I] 1) ->unitList
	<-units{<-units[I]} ->value
	TraceAllSp ("Found:" GetListCount(<-unitList) <-units[I]  <-value )
Loop
 
# method Two
 
GetTableKeys(<-units)->keys
Do (Getlistcount(<-keys) 0) 
	<-keys[I] ->k
	GetUnitsByType (<-k 1) ->unitList
	<-units{<-k} ->value
	TraceAllSp ("Found:" GetListCount(<-unitList) <-k  <-value )
Loop