use_gap

v0.2.0 Warning Fix Widget Best Practices

This rule suggests replacing SizedBox and Padding spacers inside multi-child widgets (Column, Row, etc.) with the Gap widget from the gap package. Gap automatically picks the right axis based on its parent, so you never accidentally use width in a Column or height in a Row.

Why use this rule

Using SizedBox(height: 16) for spacing works, but it is error-prone in Row (where you need width instead) and verbose in either case. Gap(16) is axis-aware, shorter, and makes the intent clearer: this is a spacer, not a box with specific dimensions. It also reduces bugs when refactoring a Column to a Row or vice versa.

See also: gap package

Don’t

Column(
  children: [
    Text('First'),
    SizedBox(height: 16),
    Text('Second'),
  ],
)

Row(
  children: [
    Text('Left'),
    SizedBox(width: 8),
    Text('Right'),
  ],
)

Do

Column(
  children: [
    Text('First'),
    Gap(16),
    Text('Second'),
  ],
)

Row(
  children: [
    Text('Left'),
    Gap(8),
    Text('Right'),
  ],
)

Configuration

To disable this rule:

plugins:
  many_lints:
    diagnostics:
      use_gap: false