Design By contract with types in runtime in c#
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using System; | |
using System.Collections.Generic; | |
using System.Linq; | |
using System.Text; | |
namespace TypesContracts | |
{ | |
class Program | |
{ | |
static void Main(string[] args) | |
{ | |
string s = Size(null);//result: argument exception | |
Console.WriteLine(Lenght(null));//result 0 | |
DivByZero(0);// result: argument exception | |
Log(5);//result: log 5 to console | |
AddTenSymbols("");//result: if result string has lenght more than 10 then log result string/ | |
Console.ReadKey(); | |
} | |
static Check<string, IsNotNull<string>> Size(Check<object, IsNotNull<object>> obj) | |
{ | |
return obj.ToString(); | |
} | |
static int Lenght(Check<string, AndReplaceByEmptyIfNull> str) | |
{ | |
string stri = str; | |
return stri.Length; | |
//return ((string)str).Length; | |
} | |
static int DivByZero(Check<int, If<int, EqualsTo<Zero>, ThenThrowArgumentException<int>>> i) | |
{ | |
return 1 / i; | |
} | |
static Check<int, If<int, BothTrue<Not<EqualsTo<Zero>>, Not<MoreThan<Ten>>>, ThenLog<int>>> Log(int i) | |
{ | |
return i; | |
} | |
static Check<string, If<string, Member<string, int, StringLenght, MoreThan<Ten>>, ThenLog<string>>> AddTenSymbols(string s) | |
{ | |
return s + "asffgsdfgd"; ; | |
} | |
} | |
public struct Check<T, U> where U : Constraint<T>, new()//we cant create shortcurs for struct or maybe we can? | |
{ | |
private T _val; | |
public Check(T val) | |
{ | |
_val = new U().CheckAndReturn(val); | |
} | |
public static implicit operator T(Check<T, U> d) | |
{ | |
return d._val; | |
} | |
public static implicit operator Check<T, U>(T d) | |
{ | |
return new Check<T, U>(d); | |
} | |
public T Val { get { return _val; } } | |
public override string ToString() | |
{ | |
return _val.ToString(); // or we can throw exception | |
} | |
public override bool Equals(object obj) | |
{ | |
return _val.Equals(obj); | |
} | |
public override int GetHashCode() | |
{ | |
return _val.GetHashCode(); | |
} | |
} | |
public abstract class Constraint<T> | |
{ | |
public abstract T CheckAndReturn(T inp); | |
} | |
public class IsNotNull<T> : Constraint<T> where T : class | |
{ | |
public override T CheckAndReturn(T inp) | |
{ | |
if (inp == null) throw new ArgumentException("bl a bla"); | |
return inp; | |
} | |
} | |
public class DefaultInsteadOfNull<T> : Constraint<T> where T : class, new()//doesnt work with string coz str doesnt have empty ctor | |
{ | |
public override T CheckAndReturn(T inp) | |
{ | |
if (inp == null) throw new ArgumentException("bl a bla"); | |
return inp == null ? new T() : inp; | |
} | |
} | |
public class AndReplaceByEmptyIfNull : Constraint<String>//string doesnt have empty ctor | |
{ | |
public override String CheckAndReturn(String inp) | |
{ | |
return inp == null ? String.Empty : inp; | |
} | |
} | |
//more cool stuff | |
public class If<T, C, D> : Constraint<T> | |
where C : Compare<T>, new() | |
where D : Then<T>, new() | |
{ | |
public override T CheckAndReturn(T inp) | |
{ | |
var comp = new C(); | |
if (comp.DoComparison(inp)) new D().Do(inp); | |
return inp; | |
} | |
} | |
public abstract class Value<V> | |
{ | |
private V _val; | |
public Value(V val) | |
{ | |
_val = val; | |
} | |
public V Get() | |
{ | |
return _val; | |
} | |
} | |
public abstract class Compare<T> | |
{ | |
public abstract bool DoComparison(T val1); | |
} | |
public abstract class Getter<T, U> | |
{ | |
public abstract U Get(T val1); | |
} | |
public class StringLenght : Getter<String, int> | |
{ | |
public override int Get(string val1) | |
{ | |
return val1.Length; | |
} | |
} | |
public class Member<VALUE, SELECTEDVALUE, GETTER, COMPARER> : Compare<VALUE> | |
where GETTER : Getter<VALUE, SELECTEDVALUE>, new() | |
where COMPARER : Compare<SELECTEDVALUE>, new() | |
{ | |
public override bool DoComparison(VALUE val1) | |
{ | |
var getter = new GETTER(); | |
var comparer = new COMPARER(); | |
return comparer.DoComparison(getter.Get(val1)); | |
} | |
} | |
public abstract class Then<T> | |
{ | |
public abstract void Do(T inp); | |
} | |
public class ThenThrowArgumentException<T> : Then<T> | |
{ | |
public override void Do(T inp) | |
{ | |
throw new ArgumentException(""); | |
} | |
} | |
public class ThenLog<T> : Then<T> | |
{ | |
public override void Do(T inp) | |
{ | |
Console.WriteLine(inp.ToString()); | |
} | |
} | |
public class Zero : Value<int> { public Zero() : base(0) { } } | |
public class One : Value<int> { public One() : base(1) { } } | |
public class Ten : Value<int> { public Ten() : base(10) { } } | |
public class MoreThan<V> : Compare<int> where V : Value<int>, new() | |
{ | |
public override bool DoComparison(int val1) | |
{ | |
var v = new V(); | |
return val1 > v.Get(); | |
} | |
} | |
public class LessThan<V> : Compare<int> where V : Value<int>, new() | |
{ | |
public override bool DoComparison(int val1) | |
{ | |
var v = new V(); | |
return val1 < v.Get(); | |
} | |
} | |
public class EqualsTo<V> : Compare<int> where V : Value<int>, new() | |
{ | |
public override bool DoComparison(int val1) | |
{ | |
var v = new V(); | |
return val1 == v.Get(); | |
} | |
} | |
public class BothTrue<C1, C2> : Compare<int> | |
where C1 : Compare<int>, new() | |
where C2 : Compare<int>, new() | |
{ | |
public override bool DoComparison(int val1) | |
{ | |
var c1 = new C1(); | |
var c2 = new C2(); | |
return c1.DoComparison(val1) && c2.DoComparison(val1); | |
} | |
} | |
public class Not<C1> : Compare<int> | |
where C1 : Compare<int>, new() | |
{ | |
public override bool DoComparison(int val1) | |
{ | |
var c1 = new C1(); | |
return !c1.DoComparison(val1); | |
} | |
} | |
} |
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