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2010-05-26T15:31:53Z

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2010-05-26T12:17:49Z

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==Dynamically invoking constructors==

<source lang="csharp">using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
public class MainClass
{
public static void Main()
{
ConstructorInfo ci = typeof(string).GetConstructor(new Type[] { typeof(char[]) });
string s = (string)ci.Invoke(new object[] {new char[] { "H", "e", "l", "l", "o" } });
Console.WriteLine(s);
}
}</source>
<pre class=codeResult>Hello</pre>

==Find matching constructor==

<source lang="csharp">using System;
using System.Reflection;

class MyClass {
public MyClass(int i) {
Console.WriteLine("Constructing MyClass(int). ");
}

public MyClass(int i, int j) {
Console.WriteLine("Constructing MyClass(int, int). ");
}

public int sum() {
return 0;
}

public bool isBetween(int i) {
return false;
}

public void set(int a, int b) {
Console.Write("Inside set(int, int). ");
}

public void set(double a, double b) {
Console.Write("Inside set(double, double). ");
}

public void show() {
Console.WriteLine("Values");
}
}

class MainClass {
public static void Main() {
Type t = typeof(MyClass);
int x;
// Find matching constructor.
ConstructorInfo[] ci = t.GetConstructors();

for(x=0; x < ci.Length; x++) {
ParameterInfo[] pi = ci[x].GetParameters();
if(pi.Length == 2) break;
}

if(x == ci.Length) {
Console.WriteLine("No matching constructor found.");
return;
}
else
Console.WriteLine("Two-parameter constructor found.\n");

}
}</source>
<pre class=codeResult>Two-parameter constructor found.</pre>

==Get constructor information: Display return type, name and parameters==

<source lang="csharp">using System;
using System.Reflection;

class MyClass {
public MyClass(int i) {
Console.WriteLine("Constructing MyClass(int). ");
}

public MyClass(int i, int j) {
Console.WriteLine("Constructing MyClass(int, int). ");
}

public int sum() {
return 0;
}

public bool isBetween(int i) {
return false;
}

public void set(int a, int b) {
Console.Write("Inside set(int, int). ");
}

public void set(double a, double b) {
Console.Write("Inside set(double, double). ");
}

public void show() {
Console.WriteLine("Values");
}
}

class MainClass {
public static void Main() {
Type t = typeof(MyClass);

// Get constructor info.
ConstructorInfo[] ci = t.GetConstructors();

Console.WriteLine("Available constructors: ");
foreach(ConstructorInfo c in ci) {
// Display return type and name.
Console.Write(" " + t.Name + "(");

// Display parameters.
ParameterInfo[] pi = c.GetParameters();

for(int i=0; i < pi.Length; i++) {
Console.Write(pi[i].ParameterType.Name + " " + pi[i].Name);
if(i+1 < pi.Length)
Console.Write(", ");
}

Console.WriteLine(")");
}
Console.WriteLine();
}
}</source>
<pre class=codeResult>Available constructors:
MyClass(Int32 i)
MyClass(Int32 i, Int32 j)</pre>

==Using a ConstructorInfo to create new instance==

<source lang="csharp">using System;
using System.Reflection;
using System.Globalization;
class Class1
{
DateTime[] dateTimes = new DateTime[10];
public DateTime this[int index]
{
get{ return dateTimes[index]; }
set{ dateTimes[index] = value;}
}

private DateTime dateOfBirth;
public DateTime DateOfBirth
{
get{ return dateOfBirth; }
set{ dateOfBirth = value; }
}

public void Test()
{
Console.WriteLine("Test method called");
}

private string field;

public string Property
{
get{ return field; }
set{ field = value; }
}

}

class MainClass{

static void Main(string[] args)
{
Type type = Type.GetType("Class1");
object o = Activator.CreateInstance(type);

type.InvokeMember("Test", BindingFlags.InvokeMethod,null, o, new object[]{});

// Using a ConstructorInfo
ConstructorInfo constructorInfo = type.GetConstructor(new Type[]{});

o = constructorInfo.Invoke(new object[]{});

type.InvokeMember("Test", BindingFlags.InvokeMethod,null, o, new object[]{});

// Type.InvokeMember
o = type.InvokeMember("Class1", BindingFlags.CreateInstance, null, null, new object[]{});

type.InvokeMember("Test", BindingFlags.InvokeMethod,null, o, new object[]{});
}
}</source>

==Utilize MyClass without assuming any prior knowledge: invoke constructor==

<source lang="csharp">using System;
using System.Reflection;
class MyClass {
public MyClass(int i) {
Console.WriteLine("Constructing MyClass(int). ");
}

public MyClass(int i, int j) {
Console.WriteLine("Constructing MyClass(int, int). ");
}

public int sum() {
return 0;
}

public bool isBetween(int i) {
return false;
}

public void set(int a, int b) {
Console.Write("Inside set(int, int). ");
}

public void set(double a, double b) {
Console.Write("Inside set(double, double). ");
}

public void show() {
Console.WriteLine("Values");
}
}

class MainClass {
public static void Main() {
Assembly asm = Assembly.LoadFrom("main.exe");

Type[] alltypes = asm.GetTypes();

Type t = alltypes[0]; // use first class found

Console.WriteLine("Using: " + t.Name);

ConstructorInfo[] ci = t.GetConstructors();

// Use first constructor found.
ParameterInfo[] cpi = ci[0].GetParameters();
object reflectOb;

if(cpi.Length > 0) {
object[] consargs = new object[cpi.Length];

// initialize args
for(int n=0; n < cpi.Length; n++)
consargs[n] = 10 + n * 20;

// construct the object
reflectOb = ci[0].Invoke(consargs);
} else
reflectOb = ci[0].Invoke(null);

}
}</source>
<pre class=codeResult>Using: MyClass
Constructing MyClass(int).</pre>

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в 15:31, 26 мая 2010

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