datetime/date_time_intl_display_extensions library

Locale-correct DateTime display via intl skeletons — the one opt-in module in lib/datetime/ that pulls the intl dependency.

The rest of this package deliberately avoids intl (see date_format_preset_utils.dart, which formats manually with injectable names in a FIXED layout). These extensions exist because a fixed layout cannot reorder components per locale: intl skeletons (yMMMd, MMMEd, jm, ...) render "Jan 15, 1945" for en_US but "15 janv. 1945" for fr_FR and "1945年1月15日" for ja_JP, AND auto-detect each locale's clock convention (12h AM/PM vs 24h). None of the logic is domain-specific; it operates on any DateTime.

Callers that format non-English locales MUST call initializeDateFormatting() (from package:intl/date_symbol_data_local.dart) once per process before invoking these methods — intl throws for an unloaded locale, and every method here catches that and degrades rather than propagating.

Split across part files purely to honor the project's 200-line file cap. The display methods are grouped into three extensions on DateTime — DateTimeIntlDisplayExtensions (offset + explicit-pattern formatting), DateTimeIntlDateDisplayExtensions (calendar-date renderings), and DateTimeIntlTimeDisplayExtensions (clock renderings). All of it is ONE library, so the private helpers stay shared across the parts and every method is still called on a plain DateTime exactly as before; the split is invisible to callers, who import this file via the barrel.

Enums

UtcTimeDisplayEnum

Clock-display presets for DateTimeIntlDisplayExtensions.utcTimeDisplay.

Extensions

DateTimeIntlDateDisplayExtensions on DateTime

Locale-correct calendar-date renderings (no clock). locale is an intl locale string (e.g. 'en_US', 'fr_FR'); null lets intl use its default.

DateTimeIntlDisplayExtensions on DateTime

Locale-correct DateTime display: UTC offset and explicit-pattern formatting. locale throughout is an intl locale string (e.g. 'en_US', 'fr_FR'); null lets intl use its default.

DateTimeIntlTimeDisplayExtensions on DateTime

Locale-correct clock renderings. locale is an intl locale string (e.g. 'en_US', 'fr_FR'); null lets intl use its default.

Functions

formatUtcOffset(Duration offset, {bool verbose = false}) → String

Formats a UTC offset Duration as UTC+H:MM / UTC-H / UTC±0.