Environment Variables in UnrealScript

Environment variables are a universal mechanism for conveying configuration information to programs. Let’s look at how to set, get, and list environment variables in UnrealScript.

class EnvironmentVariables extends Object;

var string FOO, BAR;

function Init()
{
    // To set a key/value pair, we can use a class variable
    FOO = "1";
    
    // To get a value for a key, we can access the class variable
    `log("FOO:" @ FOO);
    `log("BAR:" @ BAR); // This will be empty as we haven't set it
}

function ListEnvironmentVariables()
{
    local array<string> EnvVars;
    local string EnvVar;
    
    // In UnrealScript, we don't have direct access to system environment variables
    // Instead, we can simulate it by creating our own list
    EnvVars.AddItem("TERM_PROGRAM=UnrealEditor");
    EnvVars.AddItem("PATH=/UnrealEngine/bin");
    EnvVars.AddItem("SHELL=/bin/unrealscript");
    EnvVars.AddItem("FOO=" $ FOO);
    
    `log("Listing all environment variables:");
    foreach EnvVars(EnvVar)
    {
        `log(Split(EnvVar, "=", true));
    }
}

defaultproperties
{
    FOO=""
    BAR=""
}

In UnrealScript, we don’t have direct access to system environment variables like in other languages. Instead, we can simulate this behavior by using class variables and custom functions.

To set a key/value pair, we use class variables. To get a value for a key, we simply access these variables. If a variable hasn’t been set, it will return an empty string.

FOO = "1";
`log("FOO:" @ FOO);
`log("BAR:" @ BAR);

To list all key/value pairs in the environment, we create a custom function that simulates this behavior. In this example, we’re using an array of strings to store our “environment variables”:

function ListEnvironmentVariables()
{
    local array<string> EnvVars;
    local string EnvVar;
    
    EnvVars.AddItem("TERM_PROGRAM=UnrealEditor");
    EnvVars.AddItem("PATH=/UnrealEngine/bin");
    EnvVars.AddItem("SHELL=/bin/unrealscript");
    EnvVars.AddItem("FOO=" $ FOO);
    
    `log("Listing all environment variables:");
    foreach EnvVars(EnvVar)
    {
        `log(Split(EnvVar, "=", true));
    }
}

To run this in UnrealScript, you would typically call these functions from another class or script:

class MyGame extends GameInfo;

function PreBeginPlay()
{
    local EnvironmentVariables EnvVars;
    
    super.PreBeginPlay();
    
    EnvVars = new class'EnvironmentVariables';
    EnvVars.Init();
    EnvVars.ListEnvironmentVariables();
}

This would output something like:

FOO: 1
BAR:
Listing all environment variables:
TERM_PROGRAM
PATH
SHELL
FOO

Remember that in UnrealScript, we’re simulating environment variables. In a real UnrealScript environment, you would typically use configuration files or other UnrealEngine-specific methods to manage game settings and configurations.

Context in UnrealScript

Signals in UnrealScript

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Environment Variables in UnrealScript