Feature Request: Support for Local Variable Scoping in Functions

[hientrung]

Subject: Request to allow local variable declarations within functions to avoid "Illegal variable re-declaration" errors.

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1. Description

Currently, cgscript triggers an "Illegal variable re-declaration" error when the same variable name is used in different scopes. The engine seems to treat all variable declarations as if they share a single global namespace, even when they are defined inside independent function blocks.

2. Current Behavior (Failure Scenarios)

The compiler/interpreter fails in the following scenarios, which are standard practices in most modern programming languages:

Scenario 1: Conflict between Local and Global scope

The following code triggers an error because the variable a is declared both inside the function and in the global scope.

Function test = function() {
    string a; // Local declaration
};

string a; // Global declaration - triggers "Illegal variable re-declaration"
test.Call();

Scenario 2: Conflict between two different Function scopes

The following code triggers an error even though the variables are isolated within two independent functions.

Function test = function() {
    string a; // Local to 'test' function
};

Function hi = function() {
    string a; // Local to 'hi' function - also triggers "Illegal variable re-declaration"
};

test.Call();
hi.Call();

3. Requested Change

I would like to request an update to the scoping logic to support Local/Lexical Scoping:

• Scope Isolation: Variables declared inside a function block should be private to that function's execution context.
• Namespace Reusability: Multiple functions should be able to declare variables with the same name (e.g., string a) without interference.
• Variable Shadowing: Local variables should be allowed to have the same name as global variables without triggering re-declaration errors.

4. Why this is needed

Proper variable scoping is essential for modularity. Currently, the lack of this feature leads to:

• Namespace Pollution: Developers must use unique names for every variable across the entire script.
• High Maintenance: Harder to manage large projects and increases the risk of naming collisions.
• Code Fragility: Difficult to write reusable libraries or modules without constant naming conflicts.

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Thank you for considering this improvement to cgscript!

[hientrung]

This issue was only fixed in the compile mode, but it still crashes at runtime. However, I think this will be a major change and we can wait for it later.