Why assert is not a function?

[Chris Angelico]

On Wed, Mar 3, 2021 at 7:53 AM Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
>
> I have a curiosity. Python, as many languages, has assert as a
> keyword. Can't it be implemented as a function? Is there an advantage
> to have it as a keyword?

It could, but it would need some magic. A lot of test frameworks have
their own set of assertions and you have to pick the one you want -
for instance:

assertEqual(x, y)

instead of

assert x == y

The trouble is that, if you write a function for this, it will just
get True or False, without any explanation of the cause - making it
somewhat unhelpful when something goes wrong. To compensate, function
equivalents inevitably have to have myriad types of assertions, where
the language just needs one.

ChrisA