prefer_spacing

v0.4.0 Warning Fix Widget Best Practices

This rule detects SizedBox widgets used as uniform spacers between children in a Row, Column, or Flex, and suggests using the built-in spacing argument instead. It also catches separatedBy() and .expand() patterns that insert SizedBox spacers. Requires Flutter 3.27+.

Why use this rule

Scattering SizedBox(height: 10) between every child is verbose and easy to get wrong (miss one, use a different value, etc.). The spacing parameter on Row, Column, and Flex applies uniform spacing declaratively with a single property, making the intent clear and the code shorter. It also avoids polluting the children list with non-semantic spacer widgets.

See also: Column spacing

Don’t

Column(
  children: [
    Text('First'),
    SizedBox(height: 10),
    Text('Second'),
    SizedBox(height: 10),
    Text('Third'),
  ],
)

Do

Column(
  spacing: 10,
  children: [Text('First'), Text('Second'), Text('Third')],
)

Configuration

To disable this rule:

plugins:
  many_lints:
    diagnostics:
      prefer_spacing: false