pragmatic metaprogramming
TRANSCRIPT
Pragmatic MetaProgrammingMårten Rånge
SWETUGG 10:50
Mårten Rånge
@marten_range
Pragmatic MetaProgramming
DNRYDo Not Repeat Yourself
Loops are great
x += 1;x += 2;x += 3;x += 4;x += 5;x += 6;x += 7;x += 8;x += 9;x += 10;
Loops are great
for (var iter = 1; iter < 11; ++iter){
x += iter;}
Functions are great
var z1 = t*(y1 – x1) + x1var z2 = t*(y2 – x2) + x2var z3 = t*(y3 – x3) + x3
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);
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)
}
Repeating myself
AnException Exception
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)
}
Repeating myself
exception AnException of int*string
Repeating myself
public class MyViewModel : INotifyPropertyChanged{
int m_myProperty = 0;public int MyProperty{
get { return m_myProperty; }set{
m_myProperty = valueOnRaisePropertyChanged ("MyProperty")
}}
void OnRaisePropertyChanged (string propertyName);}
Repeating myself
int MyProperty
Repeating myself
public class MyViewModel : INotifyPropertyChanged{
int m_myProperty = 0;public int MyProperty{
get { return m_myProperty; }set{
m_myProperty = valueOnRaisePropertyChanged ("MyProperty")
}}
void OnRaisePropertyChanged (string propertyName);}
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),
};}
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),
};}
Repeating myself
Customer
long Id string FirstNamestring LastName
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),
};}
Code duplication increases maintenance cost
Looking for answers
Reflection
LINQ Expression Trees
Dynamic IL
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
public Customer ReadCustomer (IDataReader dr){
return new Customer{
Id = dr.GetInt64 (0),FirstName = dr.GetString (1),LastName = dr.GetString (2),
};}
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
Complex code increases maintenance cost
Looking for answers
Powerful
Simple concept
Language agnostic
Exit strategy
Lightweight
T4
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
class Example{<# for (var iter = 0; iter < 10; ++iter) { #>
public int X<#=iter#> = <#=iter#>;<# } #>}
T4
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
Demo.001Getting started with T4
Betty Holberton
Merge Sort Generator (1951)
Repeating myself
public class MyViewModel : INotifyPropertyChanged{
int m_myProperty = 0;public int MyProperty{
get { return m_myProperty; }set{
m_myProperty = valueOnRaisePropertyChanged ("MyProperty")
}}
void OnRaisePropertyChanged (string propertyName);}
Repeating myself
public class MyViewModel : INotifyPropertyChanged{
int m_myProperty = 0;public int MyProperty{
get { return m_myProperty; }set{
m_myProperty = valueOnRaisePropertyChanged ()
}}
void OnRaisePropertyChanged ([CallerMemberName]string name = null);}
Repeating myself
int MyProperty
Repeating myself
public class MyViewModel : INotifyPropertyChanged{
int m_myProperty = 0;public int MyProperty{
get { return m_myProperty; }set{
m_myProperty = valueOnRaisePropertyChanged ("MyProperty")
}}
void OnRaisePropertyChanged (string propertyName);}
Demo.002Generating view model classes
T4
Powerful
Simple concept
Language agnostic
Exit strategy
Lightweight
Carnelian
class Example{<# for (var iter = 0; iter < 10; ++iter) { #>
public int X<#=iter#> = <#=iter#>;<# } #>}
T4
class Example{@@> for iter in 0..10
public int X@@=iter=@@ = @@=iter=@@;@@> end
}
Carnelian
Demo.003Carnelian
Carnelian
Powerful
Simple concept
Language agnostic
Exit strategy
Lightweight
Start small
class Example{<# for (var iter = 0; iter < 10; ++iter) { #>
public int X<#=iter#> = <#=iter#>;<# } #>}
T4 is ASP/PHP for code
T4 saved me
Mårten Rånge
@marten_range
T4
T4 Addinhttp://t4-editor.tangible-engineering.com/
T4 Bloghttp://www.olegsych.com/
T4Includehttp://github.com/mrange/t4Include/
Vad tyckte du om sessionen?
svara på vägen ut