Add try-catch-finally code generation support

[Copilot]

The library had no support for generating try/catch/finally blocks. This adds first-class options for all three clauses, consistent with the existing control-flow option pattern (IfOption, LoopOption, etc.).

New types (TryCatchFinallyOption.cs)

• TryOption — renders the try { } block; owns its catch/finally clauses internally so the entire construct is encapsulated in a single child added to the parent
• CatchOption — supports bare catch, catch (Type), catch (Type var), and catch (Type var) when (filter)
• FinallyOption — renders the finally { } block
• TryCatchFinallyOptionExtensions — fluent .Catch(), .Finally(), .WithExceptionType(), .WithVariableName(), .WithWhenFilter()

Extension on MethodOption

Added MethodOption.Try(configure) to integrate naturally with the existing fluent method-building API.

Usage

new MethodOption()
    .WithKeyword("public")
    .WithName("Run")
    .WithReturnType("void")
    .Try(@try =>
    {
        @try.AppendLine("DoWork();");
        @try.Catch(c =>
        {
            c.WithExceptionType("Exception")
             .WithVariableName("ex")
             .WithWhenFilter("ex.Message.Contains(\"timeout\")")
             .AppendLine("HandleTimeout(ex);");
        });
        @try.Finally(f => f.AppendLine("Cleanup();"));
    })
    .Build();

Generates:

public void Run()
{
  try
  {
    DoWork();
  }
  catch (Exception ex) when (ex.Message.Contains("timeout"))
  {
    HandleTimeout(ex);
  }
  finally
  {
    Cleanup();
  }
}

[Copilot]

Pull request overview

Adds first-class C# code generation support for try/catch/finally blocks, integrating it into the existing option-based/fluent builder API used throughout Fengb3.EasyCodeBuilder.Csharp.

Changes:

• Introduces TryOption, CatchOption, FinallyOption, plus fluent extension methods for configuring catch signatures and filters.
• Extends MethodOption with .Try(...) to add a try statement into a generated method body.
• Adds xUnit tests covering common try/catch/finally generation scenarios.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
EasyCodeBuilder/Csharp/TryCatchFinallyOption.cs	Implements the new try/catch/finally option types and fluent configuration extensions.
EasyCodeBuilder/Csharp/MethodOption.cs	Adds MethodOption.Try(...) to integrate try/catch/finally into method generation.
EasyCodeBuilder.Test/Csharp/TryCatchFinallyTests.cs	Adds test coverage for generated try/catch/finally output.

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[Copilot]

TryOption.Build can emit a try { ... } block with no catch or finally when no clauses are added (_clauses is null). In C#, a try statement must have at least one catch or a finally, so this output can never be valid. Consider validating in Build (e.g., throw an InvalidOperationException with a clear message) or otherwise ensuring at least one clause is present before rendering.

Suggested change

	BeforeChildren?.Invoke(cb);
	cb.CodeBlock(OnChildren, "try");
	_clauses?.Invoke(cb);
	if (_clauses is null)
	{
	throw new InvalidOperationException("A try statement must include at least one catch or finally clause.");
	}
	BeforeChildren?.Invoke(cb);
	cb.CodeBlock(OnChildren, "try");
	_clauses.Invoke(cb);

[Copilot]

Clauses are stored via a multicast delegate (_clauses += clause), which makes it easy to generate invalid C# such as multiple finally blocks or catch clauses appearing after a finally (depending on call order). If this API is meant to generate valid C# by construction, consider storing catches in a list plus an optional single FinallyOption, and always render finally last (or throw if Catch() is called after Finally()).

[Copilot]

Catch(...) and Finally(...) invoke configure(...) directly. For consistency with the existing AddChild helpers (which tolerate null delegates), consider using a null-conditional invoke or explicitly throwing ArgumentNullException so the behavior is intentional and consistent across the fluent API surface.

[Copilot]

This test asserts that generating a try without any catch/finally is supported. Since try { } without at least one clause is not valid C#, this test will need to be updated/removed if TryOption is changed to enforce valid syntax (recommended).

[fengb3]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied all four review changes in e3f2c34:

1. Structured clause storage — replaced the multicast delegate with List<CatchOption> + optional FinallyOption? in TryOption, so order is always try → catches → finally regardless of call sequence.
2. Build() validation — throws InvalidOperationException if no catch or finally clause is present.
3. Invalid-ordering guards — AddCatch() throws if called after SetFinally(); SetFinally() throws if called more than once.
4. Null configure guards — Catch() and Finally() throw ArgumentNullException for null delegates.
5. Tests updated — removed the invalid TryOnly test; added TryWithoutCatchOrFinallyThrows, CatchAfterFinallyThrows, MultipleFinallyThrows, NullCatchConfigureThrows, and NullFinallyConfigureThrows.