Extension points

phil/recurrence

The library is plain PHP: it declares no service and no port, and its classes are final. What an application chooses goes through arguments.

Point	How
The time zone of the occurrences	The zone of the start given to `Recurrence::of()`, or the zone given to `RecurrenceRule::parse()` for an `UNTIL` read without one
Dates left out	The `$exclusions` of `Recurrence::of()`: cancelled occurrences, holidays the application computes
Dates added	The `$additions` of `Recurrence::of()`: a session moved to another day, an extra date
Where added and removed dates are kept	`(string) RecurrenceDates::of(...)` writes an `RDATE` or `EXDATE` line, and `RecurrenceDates::parse()` reads it back
How many occurrences are read	The `$limit` of `between()`, or `occurrences()` read lazily and stopped by the caller
Where a rule is kept	`(string) $rule` writes the RFC 5545 text the application stores, and `RecurrenceRule::parse()` reads it back
Rules in words, in other languages	Written by the application over `RecurrenceRule`'s public properties; the library writes no prose
Catching the library's errors	Every exception implements `Phil\Recurrence\Exception\RecurrenceException`

Frequencies finer than a day (HOURLY, MINUTELY, SECONDLY) are refused rather than extended: occurrences at a time of day come from the start's time.