🚀 Dynamic Coding

A reference guide on dynamic code execution across multiple programming languages. This shows how code can be executed directly from a string, either natively or through runtime compilation.

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🔑 Overview

Not all languages allow direct execution of code strings. Some provide eval or similar features natively, while others require compiling code on the fly.

✅ Languages with native support

• JavaScript (eval, new Function)
• Python (exec, eval)
• Ruby (eval)
• PHP (eval)
• Lisp-family languages (e.g., Clojure)

⚠️ Languages requiring compilation or scripting APIs

• Java
• C#
• C++
• Go
• Kotlin
• Swift
• Rust

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🧩 How It Works

1. JavaScript (native support)

let code = `
  let {a, b} = data;
  console.log("Sum =", a+b);
  console.log("Product =", a*b);
`;
new Function("data", code)({a:6, b:2});

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2. Python (native support)

code = """
a = data['a']
b = data['b']
print("Sum =", a+b)
print("Product =", a*b)
"""

data = {"a": 6, "b": 2}
exec(code)

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3. Ruby (native support)

code = "
a = data[:a]
b = data[:b]
puts \"Sum = #{a+b}\"
puts \"Product = #{a*b}\"
"

data = {a: 6, b: 2}
eval(code)

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4. PHP (native support)

<?php
$code = '
$a = $data["a"];
$b = $data["b"];
echo "Sum = " . ($a + $b) . "\n";
echo "Product = " . ($a * $b) . "\n";
';

$data = ["a" => 6, "b" => 2];
eval($code);
?>

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5. Java (via compiler API, not native)

// Requires javax.tools.JavaCompiler API (JSR-199). // Dynamically compile and execute code strings.

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6. C# (via Roslyn Scripting API)

// Requires Microsoft.CodeAnalysis.CSharp.Scripting
using Microsoft.CodeAnalysis.CSharp.Scripting;

var code = @"
var sum = data[""a""] + data[""b""];
Console.WriteLine($""Sum = {sum}"");
";

var data = new Dictionary<string,int>{{"a",6},{"b",2}};
await CSharpScript.EvaluateAsync(code, globals: new { data });

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7. C++ (no eval, needs external compiler)

• Write code to a .cpp file.
• Compile with g++ → run the binary.

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8. Go (no eval, needs runtime compiler)

• Write code to a .go file.
• Execute via go run temp.go.

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9. Kotlin (via scripting API)

// Requires kotlin.script.experimental package.

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10. Swift (via interpreter)

• Use swift - to feed and run code strings.

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11. Rust (no eval, needs compiler)

• Write code string to .rs file.
• Compile using rustc temp.rs.
• Execute binary.

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📌 JavaScript Example (Detailed)

This repository includes a working example of dynamic code execution in JavaScript.

Code

new Function('data', codeSample1_Logic)(codeSample1_Data)

Input

// Code data
let codeSample1_Data = { a: 6, b: 2 };

// Code logic
let codeSample1_Logic = `
console.log('data='+JSON.stringify(data))
let {a, b} = data
console.log('a='+a)
console.log('b='+b)
console.log('a+b='+(a+b))
console.log('a-b='+(a-b))
console.log('a*b='+(a*b))
console.log('a/b='+(a/b))
`;

Output

data={"a":6,"b":2}
a=6
b=2
a+b=8
a-b=4
a*b=12
a/b=3

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📖 Example Repository

👉 Dynamic Code in JavaScript (GitHub Example)

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⚡ Summary

• Dynamic execution is simple in scripting languages (JS, Python, Ruby, PHP).
• Compiled languages need special handling (APIs, interpreters, compilers).
• Use cases:
  • Sandboxed script execution
  • Plugins and customization
  • Learning and experimentation