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<p>One aspect of Groovy ( and Ruby, Python , etc ) I really like is the combination of closures and support for them in the Groovy DK .</p>

<p>As an example, consider iterating through every line in a text file :</p>

<h2>Groovy </h2>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
file = new File("c:/dynamic.ini");
file.eachLine{
    println(it)
}
</pre></td></tr></table>

<p>Very elegant and easy on the old eyes.</p>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
BufferedReader  input = null;
try {
      input = new BufferedReader (new FileReader("c:/dynamic.ini")); 
      String line;
      while ((line = input.readLine()) != null) {
	System.out.println(line);
      }
} finally {
   if(input != null){
       input.close();
   }
}

</pre></td></tr></table>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
Iteration.eachLine("c:/dynamic.ini", new LineHandler() {
	public void handleLine(String line) {
		System.out.println(line);
	}
});

</pre></td></tr></table>

<p>and the supporting code :</p>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre> 
public static void eachLine(String path, LineHandler handler) throws IOException {
	FileReader file = null;
	try {
		file = new FileReader(path); // Open the file.
		BufferedReader input = new BufferedReader(file);
		String line;
		while ((line = input.readLine()) != null) {
			handler.handleLine(line);
		}
	} finally {
		if (file != null) {
			file.close();
		}
	}
}
</pre></td></tr></table>
<h2>C# </h2>

<p>Apologies for my C#, I have not been writing it for very long...</p>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
string line;
using (StreamReader reader = File.OpenText(@"c:\dynamic.ini")) {
    while((line = reader.ReadLine()) != null){
        Console.WriteLine(line);
    } 
}
</pre></td></tr></table>

<p>No need to escape path string is nice</p>

<p>With C# 2.0 and the 2.0 .NET framework the addition of anonymous delegates we can produce a very concise and readable solution</p>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>

Iterators.EachLine(@"c:\dynamic.ini", delegate(string it) {
   Console.WriteLine(it);
});

</pre></td></tr></table>
<p>similar in elegance to the Groovy one.</p>

<p>This depends on the following utility class </p>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
public static class Iterators {

public delegate void Closure&lt;T>(T it);

public static void EachLine(string path, Closure&lt;string> closure) {
            string line = null;
            using (StreamReader reader = File.OpenText(path)) {
                line = reader.ReadLine();
                while (line != null) {
                    closure(line);
                    line = reader.ReadLine();
                }
            }
        }
 }
</pre></td></tr></table>

<h2>Groovinating C#</h2>

<p>You will notice that I have started implementing the Groovy DK set of collection iterators (each, findAll, find , etc ) for C# 2.0.</p>

<p>I do wish Microsoft  and Sun would have built this kind of simplicity in....</p>

<p>There are 2 possible approaches to the Collections :</p>

<ol>
	<li>Subclass and add the grooviness</li>
	<li>Add the grooviness as a set statci methods you plass the collection to</li>
</ol>

<p>Here is some perlimenary code and tests of both types.<br />
This subclasses List&lt;T&gt; and adds the groovination, and offers the same support ina static class </p>

<h2>C# 2.0 Code </h2>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
#region Using directives

using System;
using System.Collections.Generic;
using System.IO;

#endregion

namespace Groovinator {

#region Delegatros
    public class Delegatros {
        public delegate void Closure&lt;T>(T it);
        public delegate T Functor&lt;T>(T it);
        public delegate bool Predicate&lt;T>(T it);
    }

#endregion
    #region Collection Iterators

public class List&lt;T> : System.Collections.Generic.List&lt;T> {
        public void Each(Delegatros.Closure&lt;T> closure) {
            foreach (T it in this) {
                closure(it);
            }
        }
        
        public List&lt;T> FindAll(Delegatros.Predicate&lt;T> predicate) {
            //this is a bit poor 
            List&lt;T> result = new List&lt;T>();
            foreach (T it in this) {
                if (predicate(it)) {
                    result.Add(it);
                }
            }
            return result;
        }

public T Find(Delegatros.Predicate&lt;T> predicate) {
            foreach (T it in this) {
                if (predicate(it)) {
                    return it;
                }
            }
            return default(T);
        }

public void Map(Delegatros.Functor&lt;T> functor) {
            List&lt;T> result = new List&lt;T>();
            for(int i = 0;i&lt; this.Count;++i){
                this[i] = functor(this[i]);
            }
        }
    }

public static class Iterators {
        
        // Collections
        public static void Each&lt;T>(IEnumerable&lt;T> enumerable, Delegatros.Closure&lt;T> closure) {
            foreach (T it in enumerable) {
                closure(it);
            }
        }

public static List&lt;T> FindAll&lt;T>(IEnumerable&lt;T> enumerable, Delegatros.Predicate&lt;T> predicate) {
            //this is a bit poor 
            List&lt;T> result = new List&lt;T>();
            foreach (T it in enumerable) {
                if (predicate(it)) {
                    result.Add(it);
                }
            }
            return result;
        }

public static T Find&lt;T>(IEnumerable&lt;T> enumerable, Delegatros.Predicate&lt;T> predicate) {
            foreach (T it in enumerable) {
                if (predicate(it)) {
                    return it;
                }
            }
            return default(T);
        }

public static List&lt;T> Map&lt;T>(IEnumerable&lt;T> enumerable, Delegatros.Functor&lt;T> functor) {
            List&lt;T> result = new List&lt;T>();
            foreach (T it in enumerable) {
                result.Add(functor(it));
            }
            
            return result;
        }

}

#endregion
    #region File Iterators
    public static class IOIterators{
        // File related iterators
        public static void EachLine(string path, Delegatros.Closure&lt;string> closure) {
            string line = null;
            using (StreamReader reader = File.OpenText(path)) {
                line = reader.ReadLine();
                while (line != null) {
                    closure(line);
                    line = reader.ReadLine();
                }
            }
        }
    }
    #endregion
}

</pre></td></tr></table>

<h2>Some Usage Examples</h2>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
// open, print all lines of a text file , close
IOIterators.EachLine(@"c:\dynamic.ini", delegate(string it) {
    Console.WriteLine(it);
});

List&lt;string> list = new List&lt;string>();

// populate list

// print a list of string
list.Each(delegate(string it) {
    Console.WriteLine(it);
});

System.Collections.Generic.IEnumerable&lt;string> res;

// find all items matching the predicate item.Contaons("8")
res = list.FindAll(delegate(string it) {
    return it.Contains("8");
});

// find the first item where Item.Equals("10")
string ten = list.Find(delegate(string it) {
    return it.Equals("10");
});

List&lt;int> nums = new List&lt;int>();
for (int j = 1; j &lt; 11; ++j) {
    nums.Add(j);
}

// apply a functor ( multiply by 2 ) to a list of ints
nums.Map(delegate(int num) {
        return num * 2;
});

</pre></td></tr></table>