Python exec() Function

#Use the exec() Function

#A string containing valid Python code
source_string = """
def add(a, b):
    return a + b
a = 100
b = 200
print(add(a, b))
"""
#Compile the source string using the builtin compile() function
code_object = compile(source_string, "<string>", "exec")

#call the exec function with the code object
exec(code_object)

The exec() function enables execution of dynamically-generated code.

It takes one required argument, the object to be executed, this can be a string containing valid Python code or a code object generated by the builtin compile() function.

Syntax:

exec(source, globals = None, locals = None)

The function executes the arbitrary Python object given in the source arguments.

Example with strings:

exec("a = 1 + 3\nprint(a)")
//4
code = "print('Hello, World!')"
exec(code)
//Hello, World!
add_string = "def add(a, b):\n    print('{} + {} = {}'.format(a, b, a + b))\nadd(30, 50)"
exec(add_string)
//30 + 50 = 80

Using compiled code object:

The built-in compile function is used to compile a Python code from a string, it returns a code object which can then be executed by passing it as an argument to the exec() function. Examples:

code_string = "def prod(a, b):\n    print('%s * %s = %s'%(a, b, a*b))\nprod(10, 50)"
compiled_object = compile(code_string, '', 'exec')
exec(compiled_object)
//10 * 50 = 500