PuerTS 3.0 Multi-Language Comparison Cheat Sheet

This table summarizes the syntax differences between JavaScript, Lua, and Python when interacting with C# in PuerTS, for quick reference.

📖 Detailed tutorials for each language: JS | Lua | Python

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1. Environment Creation

Language	C# Code
JavaScript	var env = new ScriptEnv(new BackendV8());
Lua	var env = new ScriptEnv(new BackendLua());
Python	var env = new ScriptEnv(new BackendPython());

All three languages share a unified ScriptEnv + Backend architecture, differing only in the Backend type.

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2. C# Namespace / Type Access

Language	Syntax
JavaScript	CS.UnityEngine.Vector3 — access directly via the global CS object
Lua	local CS = require('csharp') then CS.UnityEngine.Vector3
Python	import UnityEngine.Vector3 as Vector3 or puerts.load_type('UnityEngine.Vector3')

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3. Object Creation

Language	Example
JavaScript	let v = new CS.UnityEngine.Vector3(1, 2, 3);
Lua	local v = CS.UnityEngine.Vector3(1, 2, 3) — no new
Python	v = Vector3(1, 2, 3) — no new

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4. Instance Method Calls

Language	Example	Notes
JavaScript	rect.Contains(point)	Dot syntax
Lua	rect:Contains(point)	Colon syntax (auto-passes self)
Python	rect.Contains(point)	Dot syntax

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5. Static Method Calls

Language	Example
JavaScript	CS.UnityEngine.Debug.Log('msg')
Lua	CS.UnityEngine.Debug.Log('msg') — dot syntax
Python	Debug.Log('msg') — requires import first

In Lua, static methods use dot ., instance methods use colon :; JS and Python uniformly use dot.

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6. Property Read/Write

Language	Read	Write
JavaScript	let w = rect.width	rect.width = 0.1
Lua	local w = rect.width	rect.width = 0.1
Python	w = rect.width	rect.width = 0.1

Property read/write syntax is identical across all three languages, all using dot notation.

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7. ref/out Parameters

Language	Create Container	Pass as Argument	Get Result
JavaScript	let p = puer.$ref(initialValue)	Func(p)	puer.$unref(p)
Lua	local p = {initialValue} or {}	Func(p)	p[1]
Python	p = [initialValue] or [None]	Func(p)	p[0]

Comparison example (out int b, ref int c):

// JavaScript
let outB = puer.$ref();
let refC = puer.$ref(10);
Example.InOutArgFunc(100, outB, refC);
console.log(puer.$unref(outB), puer.$unref(refC)); // 100, 20

-- Lua
local outB = {}
local refC = {10}
CS.Example.InOutArgFunc(100, outB, refC)
print(outB[1], refC[1])  -- 100, 20

# Python
outB = [None]
refC = [10]
Example.InOutArgFunc(100, outB, refC)
print(outB[0], refC[0])  # 100, 20

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8. Generic Type Creation

Language	Generic Class Name	Creating List<int>
JavaScript	List$1	puer.$generic(CS.System.Collections.Generic.List$1, CS.System.Int32)
Lua	List_1	CS.System.Collections.Generic.List_1(CS.System.Int32)
Python	List	List[System.Int32]

In Python, using import XXX imports a special generic factory type. When called with type arguments, it creates an instance of a generic type based on the number of mixed-in type arguments.

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9. Generic Method Calls

Language	Syntax
JavaScript	Call directly, V8 auto-infers type parameters
Lua	puerts.genericMethod(Type, 'MethodName', GenericArgs...)
Python	puerts.generic_method(Type, 'MethodName', GenericArgs...)

-- Lua example
local func = puerts.genericMethod(CS.MyClass, 'MyMethod', CS.System.Int32)
func(obj)

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10. Array and Indexer Access ([] Operator)

C# [] operators (arrays, List, Dictionary, custom indexers) cannot be accessed directly with [] in these three languages. You must use get_Item() / set_Item().

Language	Read (C# arr[0])	Write (C# arr[0] = val)
JavaScript	arr.get_Item(0)	arr.set_Item(0, val)
Lua	arr:get_Item(0)	arr:set_Item(0, val)
Python	arr.get_Item(0)	arr.set_Item(0, val)

⚠️ Lua uses colon : syntax for instance methods, while JS and Python use dot . syntax. This rule applies to all C# types with indexers (arrays, List, Dictionary, etc.).

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11. typeof

Language	Syntax
JavaScript	puer.$typeof(CS.UnityEngine.ParticleSystem)
Lua	require('puerts').typeof(CS.UnityEngine.ParticleSystem)
Python	puerts.typeof(ParticleSystem)

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12. null Representation

Language	Script-side null	Notes
JavaScript	null / undefined	Standard JS null values
Lua	nil	Standard Lua null value
Python	None	Standard Python null value

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13. Callbacks / Lambda

Language	Example
JavaScript	obj.Callback = (msg) => { console.log(msg); }
Lua	obj.Callback = function(msg) print(msg) end
Python	obj.Callback = lambda msg: print(msg)

Getting a script function as a delegate on the C# side:

// Same for all three languages
Action<string> fn = env.Eval<Action<string>>("script code");
fn("hello");

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14. Throwing Exceptions

Language	Syntax
JavaScript	throw new Error('msg')
Lua	error('msg')
Python	raise Exception('msg')

Exceptions thrown from the script side are wrapped as corresponding exception types on the C# side, catchable via try/catch.

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Appendix: Key API Reference Table

Feature	JavaScript (puer.xxx)	Lua (require('puerts').xxx)	Python (puerts.xxx)
Generic type	puer.$generic()	List_1(TypeArgs...) — direct call	You can import the generic directly using import (e.g., import List). For details, refer to the explanation of generics above.
Generic method	— (auto-inferred)	puerts.genericMethod()	puerts.generic_method()
typeof	puer.$typeof()	puerts.typeof()	puerts.typeof()
ref/out create	puer.$ref()	{} (table)	[] (list)
ref/out retrieve	puer.$unref()	[1]	[0]
async/await	puer.$promise(task)	—	—

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📖 Detailed tutorials for each language:

• JavaScript: Getting Started · JS to C# · C# to JS
• Lua: Getting Started · Lua to C# · C# to Lua
• Python: Getting Started · Python to C# · C# to Python