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Deprecate IMPERIAL_SYSTEM unit system and linked constants and properties

· One min read

As of Home Assistant Core 2022.11, the IMPERIAL_SYSTEM is deprecated, replaced by US_CUSTOMARY_SYSTEM. The is_metric and name properties of a unit system are likewise deprecated and should not be used.

Custom integrations referencing this unit system or these properties will need to be adjusted to use instance checks instead.

Correct:

if hass.config.units is METRIC_SYSTEM:
    pass

if hass.config.units is US_CUSTOMARY_SYSTEM:
    pass

To avoid confusion with future unit systems, the constants CONF_UNIT_SYSTEM_IMPERIAL and CONF_UNIT_SYSTEM_METRIC are also deprecated and should no longer be referenced:

  • if they were used to compare against the name of a unit system, then this is no longer needed.
  • if they were used for another reason, then local constants should be created instead.