I would argue against that approach. Make it a requirement that a given API must be used with correct values.

e.g. #hours:minutes: requires hours between 00 and 23 and minutes between 00 and 59.

If you want to convert equivalent time values, use a specific API. For example, many time implementations publicly define a seconds-based API, such as Time class>>#fromSeconds:. You can do the same with your implementation with a class-side #fromMinutes: method. (The corresponding instance methods would be #asSeconds and #asMinutes or something similar.)

Moment, I do not know if I understand you right.

so I would use the given method and use on the instance another function that takes care of the converting to or a valid time object or for example convert it to minutes and on display take care that a valid time is shown.

Do I understand you right ?

I send this personal because I cannot send to the mailing list according to some spam list