Pragmatic metaprogramming
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The document discusses the concept of pragmatic metaprogramming, highlighting the importance of avoiding code duplication and using techniques like loops and functions for efficient code management. It emphasizes the risks associated with complex code and the necessity of having an exit strategy. The content also touches on T4 code generation as a solution to reduce maintenance costs and streamline the development process.
![Repeating myself
[Serializable]
public class AnException : Exception
{
public AnException ();
public AnException (string message);
public AnException (string message, Exception exc);
protected AnException (
SerializationInfo info, StreamingContext context);
[SecurityPermission(
SecurityAction.Demand, SerializationFormatter = true)]
public override void GetObjectData (
SerializationInfo info, StreamingContext context)
}](https://image.slidesharecdn.com/pragmaticmetaprogramming-150204153333-conversion-gate02/85/Pragmatic-metaprogramming-9-320.jpg)
![Repeating myself
[Serializable]
public class AnException : Exception
{
public AnException ();
public AnException (string message);
public AnException (string message, Exception exc);
protected AnException (
SerializationInfo info, StreamingContext context);
[SecurityPermission(
SecurityAction.Demand, SerializationFormatter = true)]
public override void GetObjectData (
SerializationInfo info, StreamingContext context)
}](https://image.slidesharecdn.com/pragmaticmetaprogramming-150204153333-conversion-gate02/85/Pragmatic-metaprogramming-11-320.jpg)
![Repeating myself
public class MyViewModel : INotifyPropertyChanged
{
int m_myProperty = 0;
public int MyProperty
{
get { return m_myProperty; }
set
{
m_myProperty = value
OnRaisePropertyChanged ()
}
}
void OnRaisePropertyChanged ([CallerMemberName]string name = null);
}](https://image.slidesharecdn.com/pragmaticmetaprogramming-150204153333-conversion-gate02/85/Pragmatic-metaprogramming-37-320.jpg)
Pragmatic metaprogramming
- 4. DNRY Do Not Repeat Yourself
- 5. Loops are great x += 1; x += 2; x += 3; x += 4; x += 5; x += 6; x += 7; x += 8; x += 9; x += 10;
- 6. Loops are great for (var iter = 1; iter < 11; ++iter) { x += iter; }
- 7. Functions are great var z1 = t*(y1 – x1) + x1 var z2 = t*(y2 – x2) + x2 var z3 = t*(y3 – x3) + x3
- 8. Functions are great double Lerp (this double t, double x, double y) { return t*(y – x) + x; } var z1 = t.Lerp (x1, y1); var z2 = t.Lerp (x2, y2); var z3 = t.Lerp (x3, y3);
- 9. Repeating myself [Serializable] public class AnException : Exception { public AnException (); public AnException (string message); public AnException (string message, Exception exc); protected AnException ( SerializationInfo info, StreamingContext context); [SecurityPermission( SecurityAction.Demand, SerializationFormatter = true)] public override void GetObjectData ( SerializationInfo info, StreamingContext context) }
- 11. Repeating myself [Serializable] public class AnException : Exception { public AnException (); public AnException (string message); public AnException (string message, Exception exc); protected AnException ( SerializationInfo info, StreamingContext context); [SecurityPermission( SecurityAction.Demand, SerializationFormatter = true)] public override void GetObjectData ( SerializationInfo info, StreamingContext context) }
- 12. Repeating myself exception AnException of int*string
- 13. Repeating myself public class MyViewModel : INotifyPropertyChanged { int m_myProperty = 0; public int MyProperty { get { return m_myProperty; } set { m_myProperty = value OnRaisePropertyChanged ("MyProperty") } } void OnRaisePropertyChanged (string propertyName); }
- 15. Repeating myself public class MyViewModel : INotifyPropertyChanged { int m_myProperty = 0; public int MyProperty { get { return m_myProperty; } set { m_myProperty = value OnRaisePropertyChanged ("MyProperty") } } void OnRaisePropertyChanged (string propertyName); }
- 16. Repeating myself class Customer { public long Id ; public string FirstName; public string LastName ; } public Customer ReadCustomer (IDataReader dr) { return new Customer { Id = dr.GetInt64 (0), FirstName = dr.GetString (1), LastName = dr.GetString (2), }; }
- 17. Repeating myself class Customer { public long Id ; public string FirstName; public string LastName ; } public Customer ReadCustomer (IDataReader dr) { return new Customer { Id = dr.GetInt64 (0), FirstName = dr.GetString (1), LastName = dr.GetString (2), }; }
- 18. Repeating myself Customer long Id string FirstName string LastName
- 19. Repeating myself class Customer { public long Id ; public string FirstName; public string LastName ; } public Customer ReadCustomer (IDataReader dr) { return new Customer { Id = dr.GetInt64 (0), FirstName = dr.GetString (1), LastName = dr.GetString (2), }; }
- 20. Code duplication increases maintenance cost
- 21. Looking for answers Reflection LINQ Expression Trees Dynamic IL
- 22. Adding complexity Trading compile-time errors for run-time errors Hard to get enough test coverage Hard to understand No exit strategy Risky to change Limited
- 24. public Customer ReadCustomer (IDataReader dr) { return new Customer { Id = dr.GetInt64 (0), FirstName = dr.GetString (1), LastName = dr.GetString (2), }; }
- 25. Adding complexity Trading compile-time errors for run-time errors Hard to get enough test coverage Hard to understand No exit strategy Risky to change Limited
- 26. Complex code increases maintenance cost
- 29. Looking for answers Powerful Simple concept Language agnostic Exit strategy Lightweight
- 30. T4
- 31. class Example { public int X0 = 0; public int X1 = 1; public int X2 = 2; public int X3 = 3; public int X4 = 4; public int X5 = 5; public int X6 = 6; public int X7 = 7; public int X8 = 8; public int X9 = 9; } T4
- 32. class Example { <# for (var iter = 0; iter < 10; ++iter) { #> public int X<#=iter#> = <#=iter#>; <# } #> } T4
- 33. class Example { public int X0 = 0; public int X1 = 1; public int X2 = 2; public int X3 = 3; public int X4 = 4; public int X5 = 5; public int X6 = 6; public int X7 = 7; public int X8 = 8; public int X9 = 9; } T4
- 35. Betty Holberton Merge Sort Generator (1951)
- 36. Repeating myself public class MyViewModel : INotifyPropertyChanged { int m_myProperty = 0; public int MyProperty { get { return m_myProperty; } set { m_myProperty = value OnRaisePropertyChanged ("MyProperty") } } void OnRaisePropertyChanged (string propertyName); }
- 37. Repeating myself public class MyViewModel : INotifyPropertyChanged { int m_myProperty = 0; public int MyProperty { get { return m_myProperty; } set { m_myProperty = value OnRaisePropertyChanged () } } void OnRaisePropertyChanged ([CallerMemberName]string name = null); }
- 39. Repeating myself public class MyViewModel : INotifyPropertyChanged { int m_myProperty = 0; public int MyProperty { get { return m_myProperty; } set { m_myProperty = value OnRaisePropertyChanged ("MyProperty") } } void OnRaisePropertyChanged (string propertyName); }
- 40. Demo.002 Generating view model classes
- 41. T4 Powerful Simple concept Language agnostic Exit strategy Lightweight
- 42. Carnelian
- 43. class Example { <# for (var iter = 0; iter < 10; ++iter) { #> public int X<#=iter#> = <#=iter#>; <# } #> } T4
- 44. class Example { @@> for iter in 0..10 public int X@@=iter=@@ = @@=iter=@@; @@> end } Carnelian
- 46. Carnelian Powerful Simple concept Language agnostic Exit strategy Lightweight
- 47. Start small
- 48. class Example { <# for (var iter = 0; iter < 10; ++iter) { #> public int X<#=iter#> = <#=iter#>; <# } #> } T4 is ASP/PHP for code
- 49. T4 saved me
- 52. ”The CORRECT Way to Code a Custom Exception Class” http://bit.ly/1AsJ0UH
- 53. Vad tyckte du om sessionen? svara på vägen ut