Dart Best Practices

1. When to use this skill

Use this skill when:

• Writing or reviewing Dart code.

• Looking for guidance on idiomatic Dart usage.

2. Best Practices

Multi-line Strings

Prefer using multi-line strings (''' ) over concatenating strings with + and \n , especially for large blocks of text like SQL queries, HTML, or PEM-encoded keys. This improves readability and avoids lines_longer_than_80_chars lint errors by allowing natural line breaks.

Avoid:

final pem = '-----BEGIN RSA PRIVATE KEY-----\n' + base64Encode(fullBytes) + '\n-----END RSA PRIVATE KEY-----';

Prefer:

final pem = ''' -----BEGIN RSA PRIVATE KEY----- ${base64Encode(fullBytes)} -----END RSA PRIVATE KEY-----''';

Line Length

Avoid lines longer than 80 characters, even in Markdown files and comments. This ensures code is readable in split-screen views and on smaller screens without horizontal scrolling.

Prefer: Target 80 characters for wrapping text. Exceptions are allowed for long URLs or identifiers that cannot be broken.

Discovery

Multi-line Strings

To find candidates for multi-line strings, search for string concatenation with + involving newlines:

• Regex: ['"]\s*+\s*['"]

• Regex: +\s*['"].*\n

Line Length

• Rely on the lines_longer_than_80_chars lint from the analyzer.

Related Skills

• dart-modern-features: For idiomatic usage of modern Dart features like Pattern Matching (useful for deep JSON extraction), Records, and Switch Expressions.