Parameters aren't validated when passed via constructor

[mikekap]

class Task(luigi.Task):
    p = luigi.IntParameter()

print Task(p='hi').p  # 'hi'

While the above is a trivial case of "something will probably break down the line," this can introduce subtle bugs when e.g. a date parameter is passed to a datetime parameter (or vice-versa).

My suggestion would be to add some sort of validation, and possibly the ability to tweak the value (similar to parse) to the Parameter interface. The latter would be useful when implementing an e.g. "every N hours" parameter that automatically floors to the nearest hour.

[erikbern]

Yeah that sounds reasonable. Would you mind putting together a PR?

[Tarrasch]

Sounds great. Though beware that a couple of (bad) tests would break. Also I'm not sure what to do with the None issue.

[dlstadther]

Resolved