Why does 'raised Error' work, but 'assert' doesn't?

Question

There is a difference when I use assert and raised ValuError, why?

The following code, only stop my script when I use raise ValueError, assert does not work.

assert (len(dictA) != len(dictB)), 'Your have an .... error'

if len(dictA) != len(dictB):
    raise ValueError('Your have an ... error')

Note also that this isn't best practice usage of assert, see e.g. https://stackoverflow.com/a/945135/3001761 — jonrsharpe, Jan 16 '19 at 12:16

score 3 · Answer 1 · answered Jan 16 '19 at 12:14

3

You need to use

assert (len(dictA) == len(dictB))

The error is thrown when the condition evaluates to False.

answered Jan 16 '19 at 12:14

Filipe Aleixo

Thank you Felipe. Do you mind to explain which one (assert or valueerror) is better to use in this situation? – gusa10 Jan 16 '19 at 13:23
Depends on your use case. Check the accepted answer to this question https://stackoverflow.com/questions/40182944/difference-between-raise-try-and-assert/40183195 – Filipe Aleixo Jan 16 '19 at 13:47

1 Answers1