CODEWITHSUNDEEP
python-3.x
pancho
pancho

Reputation: 211

Is it possible to ignore all members of a module in Python3?

I want to implement a argument type checker. I've read several times about Python and Duck typing, but I'm tired of hunting bugs when I could easily enforce the type of inputs for my functions.

My plan is to implement a type checker that right after the function definition, receives the inputs and does its assertion job.

Something like this

import sanity_check
fun1(a,b):
    sanity_check.fun1(a,b)
    <do something>

fun2(a,b):
    sanity_check.fun2(a,b)
    <do something>

It is not my intention for this type checker to clearly estate what is checking (that is left for the comments on the functions), but just to enforce types.

My idea would be that after implementation, I can erase this sanity check module by just automatically erase all lines with the "sanity_check" word. So, it is not intended permanent use, just during implementation.

Onto my question. I do not want to be constantly erasing and copying back these lines whenever I want to test for real the code, since given the nature of the codes I'm implementing, I know the function call overhead will make significant delays on my codes.

Is it there a way to ignore all the members of this "sanity_check" module?

Setting all the members to None could be a way, but I do not know how to do this.

Upvotes: 0

Views: 44

Answers (1)

deceze
deceze

Reputation: 522451

It sounds like you want a combination of type annotations with a static type checker like mypy, plus some assert statements:

Assert statements are a convenient way to insert debugging assertions into a program [..] The current code generator emits no code for an assert statement when optimization is requested at compile time.

You can use this to make runtime checks in debug mode and choose to run your code using the -O flag to omit assert statements and get maximum performance.

Static type hints can catch other types of problems without incurring (significant) runtime overhead; see https://mypy.readthedocs.io/en/stable/getting_started.html#function-signatures-and-dynamic-vs-static-typing.

Example:

def foo(bar: list):
    assert len(bar) >= 3, 'List must be at least 3 long, got %d' % len(bar)
    ...

mypy will help you find bugs where you're not even passing a list into foo, while the assert statement will warn you at runtime if the list is too short, and the check can be omitted if you run the code via python -O foo.py.

Upvotes: 2

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