SDK Property Metadata

Problem Description

For better tooling support, we would like to make two improvements to the metadata on property & style declarations:

• To break up large listings of properties on an item, need to grow the set standardized categories that properties and styles can be bucketed into.
• To provide validation of numeric input, need new metadata to specify the allowed numeric range of int and Number properties.

Decision

Complete this section when a decision has been made and approved

Decision Criteria

What factors should be accounted for in a reasonable solution to the problem?

Proposed Solution(s):

Categories

• Add two new values for the category="" metadata attribute:
  • "Text" – font/paragraph styles, text color, etc.
  • "Layout" – settings that affect how a component lays out its children (padding/gap/etc.) or how a component is laid out by its parent (constraints, etc.)
• Start using the category="" attribute as applicable on [Style] metadata too, not just [Inspectable] as today.

Numeric range
There are three proposals:

Syntax A:

• minValue="N" – value must be >= N
• minValueExclusive="N" – value must be > N
• maxValue="N" – value must be <= N
• maxValueExlusive="N" – value must be < N

Syntax B:

• minValue="N" – value must be >= N
• minValue=">N" – value must be > N
• maxValue="N" – value must be <= N
• maxValue="<N" – value must be < N

Syntax C:

• range="[N,M]" – value must be >= N, <= M
• range="(N,M)" – value must be > N, < M
• range="(N,M]" – value must be > N, <= M
• range="(N" – value must be > N
• etc.

Notes:

• N (or M) is any number – for int properties it must be an int; for Number properties it must be a Number
• In syntax A or B, if both min or both max attributes are specified, tooling's numeric validation behavior is undefined.
• If the range is inverted (min > max), tooling's numeric validation behavior is undefined.

Recommended Solution:

Categories
See above.

Numeric range
Recommend syntax A. This has the least "microsyntax"iness to it.