Feature parity with Carbon: missing methods and utilities

Summary

After a comprehensive comparison with Carbon, here are features that could be valuable additions to Chronos while maintaining its minimal, immutable-only philosophy.

So:
Which of the following are useful enough to warrant their implementation?

It helps to close the gap, but at the same time we only want to include actually useful things.

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Very High Priority (Quick Wins)

These are small, high-value additions:

Factory Methods

• createFromTimestampMs(int $timestamp) - Create from millisecond timestamp (JavaScript interop)
• createFromTimestampMsUTC(int $timestamp) - Create from ms timestamp in UTC

Validation

• hasFormat(string $date, string $format): bool - Check if string matches a date format
• canBeCreatedFromFormat(string $date, string $format): bool - Validate format match without throwing

Serialization

• toArray(): array - Convert to associative array (['year' => 2024, 'month' => 1, ...])
• toIso8601ZuluString(): string - UTC ISO8601 with Z suffix (common for APIs)
• toDateTimeLocalString(): string - HTML5 datetime-local input format

Timezone

• utc(): static - Convenience method for ->setTimezone('UTC')
• shiftTimezone(DateTimeZone|string $tz): static - Change timezone keeping local time (different from setTimezone which converts)

Boundary Methods

• startOfHour(): static - Reset to hour start (X:00:00)
• endOfHour(): static - Set to hour end (X:59:59.999999)

Comparison Methods

• isStartOfDay(): bool - Check if time is 00:00:00
• isEndOfDay(): bool - Check if time is 23:59:59
• isMidnight(): bool - Alias for isStartOfDay
• isMidday(): bool - Check if time is 12:00:00

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High Priority

Rounding Methods

• round(string $unit, int $precision = 1): static - Round to nearest unit
• floor(string $unit, int $precision = 1): static - Floor to unit
• ceil(string $unit, int $precision = 1): static - Ceil to unit

Safe Creation

• createSafe(int $year, int $month, int $day, ...): static - Throws on invalid dates instead of silent overflow (e.g., Feb 31 throws instead of becoming Mar 3)

Difference Methods

• diffInMilliseconds(?DateTimeInterface $other = null, bool $absolute = true): int
• diffInMicroseconds(?DateTimeInterface $other = null, bool $absolute = true): int

DST-Safe Operations

• addRealUnit(string $unit, int $value): static - Add without DST adjustment
• subRealUnit(string $unit, int $value): static - Subtract without DST adjustment

Navigation

• nextWeekday(): static - Move to next Monday-Friday
• previousWeekday(): static - Move to previous Monday-Friday
• nextWeekendDay(): static - Move to next Saturday/Sunday
• previousWeekendDay(): static - Move to previous Saturday/Sunday

Generic Boundary Methods

• startOf(string $unit): static - Generic start of any unit
• endOf(string $unit): static - Generic end of any unit
• isStartOf(string $unit): bool - Check if at start of unit
• isEndOf(string $unit): bool - Check if at end of unit

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Medium Priority

Comparison Methods

• isNowOrFuture(): bool - True if now or in the future
• isNowOrPast(): bool - True if now or in the past
• isLongYear(): bool - Check if year has 53 weeks
• isSameQuarter(DateTimeInterface $date, bool $ofSameYear = true): bool
• isSameUnit(string $unit, DateTimeInterface $date): bool - Generic same-unit check

Properties

• $daysInYear property - Days in the year (365 or 366)
• $dayOfYear property - Day of year (1-366)

Serialization

• getTimestampMs(): int - Millisecond timestamp
• valueOf(): int - JavaScript Date valueOf (ms timestamp)
• toObject(): stdClass - Convert to stdClass

Calendar Format

• calendar(?DateTimeInterface $referenceTime = null): string - Calendar-relative format ("Today at 2:00 PM", "Yesterday at 3:00 PM", "Last Monday")

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Lower Priority (Specialized)

Precision Support

• toTimeString(string $precision = 'second'): string - Time with precision (minute/second/ms/us)
• toDateTimeString(string $precision = 'second'): string - DateTime with precision

Additional Boundaries

• startOfMinute(): static / endOfMinute(): static
• startOfSecond(): static / endOfSecond(): static
• midDay(): static - Set to 12:00:00

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Out of Scope (By Design)

These Carbon features are intentionally not planned for Chronos to maintain its minimal footprint:

• ❌ Macro system (macro(), mixin())
• ❌ 824 locale files - Chronos has basic English only
• ❌ Mutable class - Chronos is immutable-only
• ❌ CarbonInterval - Chronos uses plain DateInterval
• ❌ Full localization with Symfony Translation
• ❌ PHP 8.1 Unit/WeekDay/Month enums

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Related PRs

• #498 - withTestNow() for scoped time mocking
• #499 - Zero interval validation for periods
• #500 - "just now" for zero-second differences

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References

• Carbon comparison analysis
• Carbon documentation
• briannesbitt/Carbon#3283 - withTestNow fix
• briannesbitt/Carbon#3259 - Zero interval issue

No implementation file, test, or entry point is named. Start by reviewing the Chronos API and the linked Carbon documentation, then narrow the wishlist to a specific method or coherent group. Done would require an agreed scope, implementation details, and tests for the selected additions.