Scripting: Logic

Logic is what makes your scripts smart! It allows your code to make decisions and react to different situations. Think of it like teaching your script to think: "If this happens, then do that."

If you're new to programming logic, don't worry - we'll start from the very basics and build up gradually.

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The Problem Without Logic

Let's start with a simple example to show why we need logic:

function onCreated() {
    temp.value = 3;
    echo("value equals 1");
    echo("value equals 2");
    echo("value equals 3");
}

If you run this script, it will print ALL three messages, even though our value is only 3. That's not very smart, is it?

Output:

value equals 1
value equals 2
value equals 3

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The Solution: If Statements

We can fix this using if statements. An if statement only runs code when a certain condition is true:

function onCreated() {
    temp.value = 3;
    if (temp.value == 1) {
        echo("value equals 1");
    }
    if (temp.value == 2) {
        echo("value equals 2");
    }
    if (temp.value == 3) {
        echo("value equals 3");
    }
}

Now it will only print "value equals 3" because that's the only condition that's true!

Output:

value equals 3

Basic If Statement Syntax

if (condition) {
    // Code to run if condition is true
}

• condition: A test that results in true or false
• {}: Curly braces contain the code to run when the condition is true

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Comparison Operators

To create conditions, we use comparison operators. These compare two values and return true or false:

Operator	Meaning	Example
==	Equals	a == b (a equals b)
!=	Not equals	a != b (a does not equal b)
>	Greater than	a > b (a is greater than b)
<	Less than	a < b (a is less than b)
>=	Greater than or equal	a >= b (a is greater than or equal to b)
<=	Less than or equal	a <= b (a is less than or equal to b)

Example: Testing All Operators

function onCreated() {
    temp.a = 5;
    temp.b = 3;

    if (temp.a == temp.b) echo("a equals b");
    if (temp.a != temp.b) echo("a does not equal b");
    if (temp.a > temp.b)  echo("a is greater than b");
    if (temp.a < temp.b)  echo("a is less than b");
    if (temp.a >= temp.b) echo("a is greater than or equal to b");
    if (temp.a <= temp.b) echo("a is less than or equal to b");
}

Output:

a does not equal b
a is greater than b
a is greater than or equal to b

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Else Statements

Sometimes you want to do something when a condition is not true. That's where else comes in:

function onCreated() {
    temp.value = 2;
    if (temp.value == 3) {
        echo("Welcome, number 3!");
    } else {
        echo("Sorry, we only accept 3s here. You are: " @ temp.value);
    }
}

Output:

Sorry, we only accept 3s here. You are: 2

Else If: Multiple Conditions

You can chain multiple conditions using else if:

function onCreated() {
    temp.score = 85;

    if (temp.score >= 90) {
        echo("Grade: A - Excellent!");
    } else if (temp.score >= 80) {
        echo("Grade: B - Good job!");
    } else if (temp.score >= 70) {
        echo("Grade: C - Not bad");
    } else {
        echo("Grade: F - Study harder!");
    }
}

Output:

Grade: B - Good job!

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Logical Operators

You can combine multiple conditions using logical operators:

Operator	Meaning	Example
&&	AND (both must be true)	(a == 1 && b == 2)
||	OR (at least one must be true)	(a == 1 || b == 2)

Example: AND Operator

function onCreated() {
    temp.username = "Alice";
    temp.level = 25;

    if (temp.username == "Alice" && temp.level >= 20) {
        echo("Welcome back, Alice! You're high level enough to enter.");
    } else {
        echo("Access denied.");
    }
}

Example: OR Operator

function onCreated() {
    temp.day = "Saturday";

    if (temp.day == "Saturday" || temp.day == "Sunday") {
        echo("It's the weekend! Time to relax.");
    } else {
        echo("It's a weekday. Time to work!");
    }
}

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Range Checking

When you need to check if a value falls within a specific range, GraalScript provides a cleaner syntax using the in operator:

Using the in Operator for Ranges

if (value in |min,max|) {
    // Code to run if value is between min and max (inclusive)
}

Example: Range Checking

function onCreated() {
    temp.playerLevel = 15;
    temp.playerX = 5;
    temp.playerY = 8;

    // Check if player level is between 10 and 20
    if (temp.playerLevel in |10,20|) {
        echo("Player is in the intermediate level range");
    }

    // Check if player is within safe zone coordinates
    if (temp.playerX in |0,10| && temp.playerY in |0,10|) {
        echo("Player is in the safe zone");
    }
}

Comparing Range Checking Methods

function onCreated() {
    temp.score = 85;

    // Traditional way (longer)
    if (temp.score >= 80 && temp.score <= 90) {
        echo("Good score! (Traditional method)");
    }

    // Using range operator (cleaner)
    if (temp.score in |80,90|) {
        echo("Good score! (Range method)");
    }
}

Both methods work the same way, but the in |min,max| syntax is more readable and less prone to errors when checking ranges.

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Loops: Repeating Code

Sometimes you need to repeat the same code multiple times. Instead of copying and pasting, you can use loops!

While Loops

A while loop repeats code as long as a condition remains true:

function onCreated() {
    temp.count = 1;

    while (temp.count <= 3) {
        echo("Count is: " @ temp.count);
        temp.count++; // Increase count by 1
    }

    echo("Loop finished!");
}

Output:

Count is: 1
Count is: 2
Count is: 3
Loop finished!

⚠️ Warning: Make sure your condition eventually becomes false, or you'll create an infinite loop!

For Loops (Traditional)

For loops are perfect when you know exactly how many times you want to repeat something:

function onCreated() {
    // Count from 0 to 2 (3 times total)
    for (temp.i = 0; temp.i < 3; temp.i++) {
        echo("Loop number: " @ temp.i);
    }
}

Output:

Loop number: 0
Loop number: 1
Loop number: 2

For Loop Syntax:

for (start; condition; increment) {
    // Code to repeat
}

• start: Initialize the counter variable
• condition: Loop continues while this is true
• increment: What happens after each loop (usually ++ to add 1)

For Loops with Arrays (For-Each)

The most useful type of loop is iterating through arrays. GraalScript2 makes this super easy:

function onCreated() {
    temp.names = {"Ruan", "Fireenn", "Cody"};

    // Loop through each name in the array
    for (temp.name : temp.names) {
        echo("Hello, " @ temp.name @ "!");
    }
}

Output:

Hello, Ruan!
Hello, Fireenn!
Hello, Cody!

For-Each Syntax:

for (variable : array) {
    // Code runs for each item in the array
    // 'variable' contains the current item
}

Practical Loop Examples

Example 1: Processing Player Inventory

function checkInventory() {
    temp.inventory = {"Sword", "Shield", "Potion", "Key"};

    echo("Your inventory contains:");
    for (temp.item : temp.inventory) {
        echo("- " @ temp.item);
    }
}

Example 2: Counting Down

function countdown() {
    temp.seconds = 5;

    while (temp.seconds > 0) {
        echo("Countdown: " @ temp.seconds);
        temp.seconds--;
        sleep(1); // Wait 1 second
    }

    echo("Blast off!");
}

Loop Control Keywords

• break: Exit the loop immediately
• continue: Skip to the next iteration

function onCreated() {
    temp.numbers = {1, 2, 3, 4, 5};

    for (temp.num : temp.numbers) {
        if (temp.num == 3) {
            continue; // Skip 3
        }
        if (temp.num == 5) {
            break; // Stop before 5
        }
        echo(temp.num);
    }
}

Output:

1
2
4

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Practice Time!

Try modifying these examples and experiment with different values to get comfortable with logic statements. Understanding these concepts is crucial for creating interactive and dynamic scripts!