Use Extension Methods Skill

This skill helps identify opportunities to use the project's custom extension methods for cleaner, more idiomatic code.

Extension Methods Available

StringExtensions (CSharperMcp.Server.Extensions)

• •

  IsNullOrEmpty() - Extension method wrapper for string.IsNullOrEmpty(value)

  • •Use: myString.IsNullOrEmpty() instead of string.IsNullOrEmpty(myString)
• •

  IsNullOrWhiteSpace() - Extension method wrapper for string.IsNullOrWhiteSpace(value)

  • •Use: myString.IsNullOrWhiteSpace() instead of string.IsNullOrWhiteSpace(myString)

CollectionExtensions (CSharperMcp.Server.Extensions)

• •OrEmpty<T>() - Returns the collection or an empty collection if null
  • •Works with: IEnumerable<T>, List<T>, T[], IReadOnlyList<T>
  • •Use: nullableList.OrEmpty().Where(...) instead of (nullableList ?? []).Where(...)
  • •Enables fluent null-safe chaining without the ?. operator

When to Use This Skill

Invoke this skill when:

• •Reviewing code that has verbose null checks on strings or collections
• •Refactoring code to be more fluent and readable
• •Writing new code that needs null-safe collection operations
• •Seeing patterns like (collection ?? []) or string.IsNullOrEmpty(variable)

Instructions

When this skill is invoked:

1. •

   Search for opportunities: Look for these patterns in the codebase:

   • •string.IsNullOrEmpty(variable) → Replace with variable.IsNullOrEmpty()
   • •string.IsNullOrWhiteSpace(variable) → Replace with variable.IsNullOrWhiteSpace()
   • •(collection ?? []) → Replace with collection.OrEmpty()
   • •collection?.Where(...) or collection?.Select(...) where null results in no action → Consider collection.OrEmpty().Where(...)
2. •

   Apply transformations:

   • •Add using directive if needed: using CSharperMcp.Server.Extensions;
   • •Replace static method calls with extension method calls
   • •Replace null-coalescing patterns with .OrEmpty() calls
   • •Ensure the code remains semantically equivalent
3. •

   Verify namespace:

   • •These extension methods are in the CSharperMcp.Server.Extensions namespace
   • •They are internal static classes, accessible within the CSharperMcp.Server project and test projects
4. •

   Report changes: Provide a summary of:

   • •Number of occurrences found
   • •Files modified
   • •Specific transformations applied

Examples

Before (String)

if (string.IsNullOrEmpty(fileName))
{
    return;
}

if (string.IsNullOrWhiteSpace(userInput))
{
    throw new ArgumentException("Input cannot be empty");
}

After (String)

using CSharperMcp.Server.Extensions;

if (fileName.IsNullOrEmpty())
{
    return;
}

if (userInput.IsNullOrWhiteSpace())
{
    throw new ArgumentException("Input cannot be empty");
}

Before (Collections)

var items = nullableList ?? [];
foreach (var item in items)
{
    Process(item);
}

var filtered = (diagnostics ?? []).Where(d => d.Severity == DiagnosticSeverity.Error).ToList();

After (Collections)

using CSharperMcp.Server.Extensions;

var items = nullableList.OrEmpty();
foreach (var item in items)
{
    Process(item);
}

var filtered = diagnostics.OrEmpty().Where(d => d.Severity == DiagnosticSeverity.Error).ToList();

Constraints

• •Only use these extension methods within the CSharperMcp.Server project and its test projects
• •Do not modify the extension method implementations themselves unless explicitly requested
• •Maintain semantic equivalence - ensure the behavior doesn't change
• •These are utility methods; use them where they improve readability, not everywhere possible

Usage

Invoke this skill with:

/use-extensions

Or with a specific scope:

/use-extensions src/CSharperMcp.Server/Services/