ironclad

ironclad helps developers write defensive, self-documenting Python code.

It enforces parameter types, constrains values with predicates or enums, and raises precise errors on violation—keeping interfaces explicit and code clean. Simple, composable guards harden functions and classes with correctness and security, with minimal overhead and maximum readability.

Features

• Strict type checks: Fail fast on mismatches with clear TypeErrors.
• Value constraints: Allowlists, enums, ranges, and custom predicates.
• Composable guards: Combine checks for rich, readable contracts.
• Low-boilerplate API: Keep validation close to the signature, not scattered.
• Security-minded: Reduce attack surface from unexpected inputs.

Installation

You can install ironclad in one of two ways:

1. Install via pip:

pip install ironclad

2. Clone this repository:

git clone https://github.com/Zentiph/ironclad

Quick Start

Importing the library:

>>> import ironclad as ic

Ensuring strict type enforcements on functions:

>>> # enforcing types with instance/type spec checks
>>> @ic.enforce_types(price=float, tax_rate=float)
... def add_sales_tax(price, tax_rate):
...     return price * (1 + tax_rate)
...
>>> add_sales_tax(50.0, 0.08)
54.0
>>> add_sales_tax(50.0, "0.08")
TypeError: add_sales_tax(): 'tax_rate' expected 'float', got 'str' with value '0.08'
>>>
>>> # enforcing types with type annotations
>>> @ic.enforce_annotations()
... def get_even(l: list[int]) -> list[int]:
...     return [e for e in l if e % 2 == 0]
...
>>> get_even([1, 2, 3])
[2]
>>> get_even([1.0, 2.0, 3.0])
TypeError: get_even(): 'l' expected 'list[int]', got 'list' with value [1.0, 2.0, 3.0]

Creating type-enforced runtime overloads:

>>> @ic.runtime_overload
... def describe(x: int):
...     return f"int: {x}"
...
>>> @describe.overload
... def _(x: str):
...     return f"str: '{x}'"
...
>>> describe(1)
'int: 1'
>>> describe("hi")
"str: 'hi'"
>>> describe(2.3)
InvalidOverloadError: No overload of describe() matches (float). Candidates: describe(x: int) | describe(x: str)

Creating predicates

>>> is_pos = ic.predicates.Predicate[int](
...     lambda x: x > 0, "is positive"
... )
>>> is_pos(4)
True
>>> is_pos(-1)
False

Documentation

ironclad's documentation is deployed on GitHub Pages.

Contributions

See the contributing page.

License

See the license page.