Length() schema validator does not interpolate

[jenstroeger]

It looks like

colander/src/colander/__init__.py

Lines 557 to 558 in 6cc5ddb

	min_err = _(self.min_err, mapping={'min': self.min})
	raise Invalid(node, min_err)

should actually be

min_err = _(self.min_err, mapping={'min': self.min}).interpolate()
raise Invalid(node, min_err)

and likewise with max_error below. Otherwise the raised Invalid() exception will contain

Longer than maximum length ${max}

[stevepiercy]

In the tests, interpolate() is called. I wonder if that is to allow translations? See Change History

[jenstroeger]

Hmm, that’s an interesting choice — the raised exception doesn’t contain the final error string but I’m supposed to expand/interpolate values on it?

I wonder if that is to allow translations?

The translated string (without expanded values) is already part of the exception object, though, then why not expand its values too?

Also, it might be problematic for users to delegate .interpolate() because it might fail if the Invalid exception doesn’t contain a a TranslationString — or is it guaranteed that it does? Just feels odd to me to expect users of an exception to continue manipulating the exception message 🤔