Call a Function Dynamically by Name in Python

Use globals() to look up and call a function by its name as a string, with optional arguments.

Easy Python 3.9+ Aug 9, 2026 Functions & basics 13 views 0 copies

globals dynamic-dispatch reflection

Python code

25 lines

Python 3.9+

def greet():
    return "Hello from greet!"

def add(a, b):
    return a + b

def multiply(a, b):
    return a * b

if __name__ == "__main__":
    func_name = "add"
    args = (3, 5)
    
    # Call function dynamically by name from globals
    result = globals()[func_name](*args)
    print(f"{func_name}({', '.join(map(str, args))}) = {result}")
    
    func_name = "multiply"
    args = (4, 6)
    result = globals()[func_name](*args)
    print(f"{func_name}({', '.join(map(str, args))}) = {result}")
    
    func_name = "greet"
    result = globals()[func_name]()
    print(f"{func_name}() = {result}")

Output

stdout

add(3, 5) = 8
multiply(4, 6) = 24
greet() = Hello from greet!

How it works

The globals() function returns a dictionary representing the current global symbol table, mapping names to their values. Accessing globals()[func_name] retrieves the function object associated with the string name. The * unpacking operator passes each element of the tuple args as a separate argument to the function. This approach works for any callable defined at the module level, including imported functions passed through globals().

Common mistakes

Forgetting to use the `*` operator when passing a tuple of arguments.
Assuming the function name exists, which raises a `KeyError` if not.
Trying to call methods or nested functions that are not in the global scope.

Variations

Use `locals()` instead of `globals()` when the function is defined inside another function.
Use `getattr(module, func_name)` to call a function imported from a module.

Real-world use cases

Dispatching HTTP handlers based on a route string without writing a long if‑else chain.
Building a plugin system where plugin names are read from a config file and invoked at runtime.
Implementing a calculator CLI that maps operator symbols to function names entered by the user.

Call a Function Dynamically by Name in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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