bx-jython: Execute Python in BoxLang

Installation

install-bx-module bx-jython
# CommandBox
box install bx-jython

BIFs

Basic Usage

// Execute inline Python
jythonEval( "print('Hello from Python!')" )

// Execute Python from a file
jythonEvalFile( "/app/scripts/process.py" )

// Python with arithmetic
jythonEval( "
result = 5 * 10
print('Result:', result)
" )

Variable Bindings

BoxLang automatically binds all variables scope values into the Python engine. Use them as native Python variables:

// Set variables in BoxLang
variables.name    = "Luis Majano"
variables.message = "Hello from BoxLang"

// These are available directly in Python
jythonEval( "print(name)" )            // Luis Majano
jythonEval( "print(message.upper())" ) // HELLO FROM BOXLANG

Using Python Modules (Files)

# /app/scripts/mathutils.py
def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)

def fibonacci(n):
    a, b = 0, 1
    for _ in range(n):
        a, b = b, a + b
    return a

// Load the Python module
jythonEvalFile( "/app/scripts/mathutils.py" )

// Call the Python function
result = jythonEval( "factorial(10)" )
fib    = jythonEval( "fibonacci(20)" )
println( result )  // 3628800
println( fib )     // 6765

bx:jython Component

Use the component for larger multi-line Python blocks captured in a variable:

bx:jython variable="result" {
    writeOutput( "
x = 10
y = 20
sum = x + y
product = x * y
print(f'Sum: {sum}, Product: {product}')
" )
}

Capturing the Result

The jythonEval() / jythonEvalFile() functions return a struct:

engineResult = jythonEval( "42 + 8" )

engineRef  = engineResult.engine       // Reference to the Jython engine
globalScope = engineResult.globalScope // JSR223 global scope
engineScope = engineResult.engineScope // JSR223 engine scope

Common Patterns

// Use Python for math/scientific processing not easily available in BoxLang
variables.numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
jythonEvalFile( "/app/scripts/statistics.py" )
mean   = jythonEval( "mean(numbers)" )
stddev = jythonEval( "std_dev(numbers)" )

Common Pitfalls

• ✅ All variables in the BoxLang variables scope are automatically accessible in Python — no explicit passing needed
• ❌ Python uses indentation for blocks — ensure your code strings use consistent indentation
• ✅ Use jythonEvalFile() for complex Python logic; use jythonEval() for quick invocations
• ❌ Jython runs Python 2.7 syntax (Jython's Python compatibility level) — not Python 3.x