1.6 KiB
Structural Patterns
Patterns detected by the absence of a keyword or interface. These require codebase-wide counting scans, not single-file matching.
Seal Classes for Devirtualization
🟡 DO seal all leaf classes (those not subclassed) | .NET Core 3.0+
Sealing lets the JIT devirtualize/inline virtual calls and use pointer comparison for type checks. Every non-abstract, non-static class that is not subclassed should be sealed.
Detection: This is an absence pattern — scan for classes that are NOT sealed.
# Count unsealed (non-abstract, non-static) classes
grep -rn --include='*.cs' -E '^\s*((public|internal|private|protected|file)\s+)?(partial\s+)?class ' --exclude-dir=bin --exclude-dir=obj . | grep -v 'sealed' | grep -v 'abstract' | grep -v 'static' | wc -l
# Count already-sealed classes (verify the inverse)
grep -rn --include='*.cs' 'sealed class' --exclude-dir=bin --exclude-dir=obj . | wc -l
Exclusions: Do not seal classes that are subclassed elsewhere in the codebase. Identifying base classes requires manual review — grep for : ClassName patterns and cross-reference, but expect false positives from interface implementations and generic constraints.
❌
internal class MyHandler : Base
{ public override int Run() => 42; }
✅
internal sealed class MyHandler : Base
{ public override int Run() => 42; }
Impact: Virtual calls up to 500x faster; type checks ~25x faster. Severity scales with count.
Scale-based severity:
- 1-10 unsealed leaf classes → ℹ️ Info
- 11-50 unsealed leaf classes → 🟡 Moderate
- 50+ unsealed leaf classes → 🟡 Moderate (elevated priority)