[threeten-dev] [threeten-develop] TemporalAdder and TemporalSubtractor

[Stephen Colebourne]

On 21 December 2012 07:54, Xueming Shen <xueming.shen at oracle.com> wrote:
A TemporalPeriod concept is reasonable, however I don't think it
removes the need for Adder/Subtractor.

Consider the a balanced equivalence:

 Temporal - defines the date-time type
 TemporalAdjuster - deifnes how to make the adjustment

 TemporalPeriod - defines the period type
 TemporalAdder/Subtractor - defines how to add/subtract

Currently, we don't have TemporalPeriod, primarily because we don't
have period formatting (a useful thing for JDK9 maybe).

Under this balanced equivalence approach, the TemporalPeriod would
look something like this:

 isSupported(Unit)
 get(Unit)
 getLong(Unit)

ie, it would provide access to the unit-long map, not the
addition/subtraction (which is what would be needed for a period
formatter)

By contrast, your chosen set of methods for TemporalPeriod are really
an extended set from Adder/Subtractor, and would not fulfil the period
formatter use case.

Stephen