Mastering Reflection and Dynamic Programming

Table of Contents

1. Deep Dive into Reflection Fundamentals

   • The Reflection Type System

   • Assembly Loading Strategies

   • Advanced Member Discovery

2. Dynamic Programming Techniques

   • Dynamic Instantiation Patterns

   • Method Invocation Optimization

   • Late-Bound Delegates

3. Performance Optimization

   • Reflection Caching Strategies

   • Emit vs Reflection Tradeoffs

   • Benchmark Comparisons

4. Real-World Applications

   • Plugin Architectures

   • Dynamic Proxies

   • Expression Tree Compilation

5. Advanced Scenarios

   • Cross-Assembly Reflection

   • Security Considerations

   • Debugging Techniques

1. Deep Dive into Reflection Fundamentals

1.1 The Reflection Type System Hierarchy

Key insights:

• Type is the gateway to all reflection operations

• All member types derive from MemberInfo

• Method and constructor information shares common base class

1.2 Assembly Loading Strategies

Loading Context Comparison:

1.3 Advanced Member Discovery

Beyond basic GetMethods(), C# offers granular control:

BindingFlags Cheat Sheet:

2. Dynamic Programming Techniques

Dynamic programming in C# leverages reflection to create flexible, runtime-determined behavior. Below are detailed explanations of each subsection.

2.1 Dynamic Instantiation Patterns

Option 1: Activator (Simplest)

The Activator.CreateInstance method is the easiest way to instantiate objects dynamically, but it has limitations:

Pros:

• Simple and concise.

• Works well for types with parameterless constructors.

Cons:

• Slower than direct instantiation.

• Limited control over constructor selection.

Option 2: ConstructorInfo (More Control)

For better performance and flexibility, use ConstructorInfo:

When to use:

• When you need to select a specific constructor.

• When performance is a concern (caching ConstructorInfo improves speed).

Option 3: FormatterServices (Bypass Constructors)

For advanced scenarios where you want to skip constructors (e.g., deserialization):

Use cases:

• Custom serialization.

• High-performance object creation (but requires manual initialization).

2.2 Method Invocation Optimization

Standard Reflection (Slow)

Drawbacks:

• Slow due to parameter boxing and runtime checks.

• Not suitable for high-frequency calls.

Delegate Cache (Faster)

Compile a delegate once and reuse it:

Performance gain:
✔ 20-100x faster than raw reflection.

Expression Tree Compilation (Fastest)

For near-native speed, compile a lambda at runtime:

Best for:
✔ High-performance scenarios (e.g., serialization, ORMs).

2.3 Late-Bound Delegates

Sometimes, you need dynamic delegates for unknown methods at compile time:

Use cases:
✔ Event handlers.
✔ Callback mechanisms in plugins.Performance Benchmark:

3. Performance Optimization

3.1 Reflection Caching Strategies

Basic Cache:

Hierarchical Cache:

3.2 Emit vs Reflection Tradeoffs

Emit Example (Dynamic Method Generation):

4. Real-World Applications

4.1 Plugin Architectures

4.2 Dynamic Proxies

5. Advanced Scenarios

5.1 Cross-Assembly Reflection

Reflection across multiple assemblies requires careful handling.

Loading Dependencies

Finding Types Across Assemblies

Strong-Named Assembly Resolution

5.2 Security Considerations

Reflection can bypass access modifiers, so security is critical.

Partial Trust Restrictions

Secure Critical Operations

Avoiding Malicious Code Execution

5.3 Debugging Dynamic Code

Debugging dynamically generated code requires special techniques.

Inspecting Dynamic Assemblies

Debugging Dynamic Methods

Using Debugger Attributes

Conclusion

This guide has explored reflection from basic type inspection to advanced code generation techniques. Key takeaways:

1. Understand the reflection hierarchy - Know how Type, MethodInfo, and related classes interact

2. Optimize performance - Cache reflection objects, use delegates, or generate IL

3. Apply patterns properly - Choose the right approach for plugins, proxies, or serialization

4. Consider security - Reflection requires careful permission management

5. Debug effectively - Special techniques needed for dynamic code