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.