Desktop Developer - Author(s): Christiaan Baes (chrissie1)

Fody Anotar weaving and logging combined into one package.

Christiaan Baes (chrissie1) — Thu, 25 Apr 2013 06:53:00 +0000

Introduction

I said it once and I will say it again. Logging is very important once your app goes live. It's the best way for you to find out what the user did to destroy your sanity.
I am always on the lookout for new and exiting things that will make logging easier for me. I want less code but maximum information.
You can get lots of information with Gibraltar's Loupe but you can get even less code and more information with Anotar.

The code

It's easy.

Just add the Anotar.Nlog package from nuget and then add some config for nlog. Like this.

Code: xml

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog"/>
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5"/>
</startup>
<system.serviceModel>
<bindings/>
<client/>
</system.serviceModel>
<nlog>
<targets>
<target name="file" type="File" fileName="_${level}.log" layout="${longdate} ${threadid} [${level:uppercase=true}] ${message}" archiveFileName="_${level}.{#}.log" archiveAboveSize="1048576" archiveNumbering="Sequence" maxArchiveFiles="10" concurrentWrites="true" keepFileOpen="false" encoding="iso-8859-2"/>
</targets>
<rules>
<logger name="*" minlevel="Debug" writeTo="file"/>
</rules>
</nlog>
</configuration>

And try it with this code.

Code: vbnet

Module Module1

Sub Main()
Dim l As New Logthing
l.TestSub()
Console.WriteLine(l.TestFunction)
Anotar.NLog.Log.Info("Some info in a static method")
End Sub

Public Class Logthing
Public Sub TestSub()
Anotar.NLog.Log.Debug("My message for sub")
End Sub

Public Function TestFunction() As String
Anotar.NLog.Log.Debug("My message for function")
Return "This thing"
End Function

End Class

End Module

This is then the resulting debug log file.

2013-04-25 13:24:00.1197 8 [DEBUG] Method: 'System.Void ConsoleApplication1.Module1/Logthing::TestSub()'. Line: ~12. My message for sub
2013-04-25 13:24:00.1387 8 [DEBUG] Method: 'System.String ConsoleApplication1.Module1/Logthing::TestFunction()'. Line: ~16. My message for function

And the info file.

2013-04-25 13:24:00.1387 8 [INFO] Method: 'System.Void ConsoleApplication1.Module1::Main()'. Line: ~7. Some info in a static method

The lines seem to be correct and the other information too.

But how does Fody do it?

Well, it changes your code at compile time.

This for instance is the LogThing class after a decompile by JustDecompile.

Code: vbnet

Public Class Logthing
Private Shared AnotarLogger As Logger

Shared Sub New()
Logthing.AnotarLogger = LogManager.GetLogger("ConsoleApplication1.Module1/Logthing")
End Sub

<DebuggerNonUserCode> _
Public Sub New()
MyBase.New()
End Sub

Public Function TestFunction() As String
Dim V_2 As Object() = New Object(0)
Dim V_1 As String = "My message for function"
V_1 = String.Concat("Method: 'System.String ConsoleApplication1.Module1/Logthing::TestFunction()'. Line: ~16. ", V_1)
Logthing.AnotarLogger.Debug(V_1, V_2)
Dim TestFunction As String = "This thing"
Return TestFunction
End Function

Public Sub TestSub()
Dim V_1 As Object() = New Object(0)
Dim V_0 As String = "My message for sub"
V_0 = String.Concat("Method: 'System.Void ConsoleApplication1.Module1/Logthing::TestSub()'. Line: ~12. ", V_0)
Logthing.AnotarLogger.Debug(V_0, V_1)
End Sub
End Class

As you can see it is not doing any reflection in your code. It just replaces your Log.Debug code with other code. Which means it should be faster at runtime.

This also means that compiling will be slower, because it has to change your code. How much? No idea.

Conclusion

I like this.

Original post blogged on LessThanDot.

ServiceStack.Text has a nice extension method called Dump and it has a few friends

Christiaan Baes (chrissie1) — Mon, 31 Dec 2012 07:49:00 +0000

Introduction

Yesterday I was adding a pdf feature to my Nancy service. And I was outputting my objects to the pdf like this.

Code: csharp

foreach (var prop in model.GetType().GetProperties())
{
oDoc.Add(new Paragraph(prop.Name + ":" + prop.GetValue(model).ToString()));
}

But we all know this is far from finished and will only work in the most simple of cases, once you add complex types to your type the results will be less than optimal.

Of course you are not alone in this world and other people have had to do this to. And Demis Bellot even made a nuget package out of his solution. So here is Servicestack.Text and the Dump extension method and friends.

Dump

So go ahead and look for servicestack.text on nuget and add it to your project.

First of all I would like to change my method above to use the Dump() method.

And so my method now looks like this.

Code: chsarp

protected virtual Action<Stream> GetPdfContents(TModel model)
{
return stream =>
{
var oDoc = new Document(PageSize.A4);
PdfWriter.GetInstance(oDoc, stream);
oDoc.Open();
oDoc.Add(new Paragraph(model.Dump()));
oDoc.Close();
};
}

So you just need you object and call the Dump() extension method on it and the output will look like this.

{
propertyname: value,
propertyname2: value
}

Nicely formatted JSV.

Yep that's it.

The output now looks like this.

Or I could output a list of objects and that would look like this.

And that is very convenient. This is the the same as doing SerializeAndFormat().

PrintDump

And do you remember this code?

Code: csharp

var trees = http.Get("http://localhost:65367/trees");
foreach (var t in trees.DynamicBody.Trees)
{
Console.WriteLine(t.Id);
Console.WriteLine(t.Genus);
}
var result = http.Get("http://localhost:65367/trees/1");
var tree = result.DynamicBody;
Console.WriteLine(tree.Id);
Console.WriteLine(tree.Genus);

Lots of Console.Writelines and not very robust.

Code: csharp

var trees = http.Get("http://localhost:65367/trees");
trees.StaticBody<Object>().PrintDump();
var result = http.Get("http://localhost:65367/trees/1");
result.StaticBody<Object>().PrintDump();

PrintDup won't work on dynamic objects so I switched to a staticobject, but easyhttp doesn't mind.

And I get this as the result.

{
Trees:
[
{
Id: 1,
Genus: Fagus
},
{
Id: 2,
Genus: Quercus
},
{
Id: 3,
Genus: Betula
},
{
Id: 4,
Genus: Fagus
},
{
Id: 5,
Genus: Quercus
},
{
Id: 6,
Genus: Betula
},
{
Id: 7,
Genus: Fagus
},
{
Id: 8,
Genus: Quercus
},
{
Id: 9,
Genus: Betula
},
{
Id: 10,
Genus: Fagus
},
{
Id: 11,
Genus: Quercus
},
{
Id: 12,
Genus: Betula
},
{
Id: 13,
Genus: Fagus
},
{
Id: 14,
Genus: Quercus
},
{
Id: 15,
Genus: Betula
}
],
NumberOfTrees: 15
}
{
Id: 1,
Genus: Fagus
}

Genius.

SerializeToString

And if you on't like the formatting then you can use SerializeToString().

Code: csharp

var trees = http.Get("http://localhost:65367/trees");
Console.WriteLine(trees.StaticBody<Object>().SerializeToString());
var result = http.Get("http://localhost:65367/trees/1");
Console.WriteLine(result.StaticBody<Object>().SerializeToString());

Which will have this kind of output.

{"Trees":[{"Id":1,"Genus":"Fagus"},{"Id":2,"Genus":"Quercus"},{"Id":3,"Genus":"B
etula"},{"Id":4,"Genus":"Fagus"},{"Id":5,"Genus":"Quercus"},{"Id":6,"Genus":"Bet
ula"},{"Id":7,"Genus":"Fagus"},{"Id":8,"Genus":"Quercus"},{"Id":9,"Genus":"Betul
a"},{"Id":10,"Genus":"Fagus"},{"Id":11,"Genus":"Quercus"},{"Id":12,"Genus":"Betu
la"},{"Id":13,"Genus":"Fagus"},{"Id":14,"Genus":"Quercus"},{"Id":15,"Genus":"Bet
ula"}],"NumberOfTrees":15}
{"Id":1,"Genus":"Fagus"}

Conclusion

These are methods that come in very handy when you do a spike or they would even come in handy for debugging, sometimes even in production.

And there are even more extension methods in that little package. You can find them all on their github page. Just look at ToJson and ToXml.

Original post blogged on LessThanDot.

Batch renaming files with powershell

Christiaan Baes (chrissie1) — Thu, 27 Dec 2012 15:13:00 +0000

I like powershell and from time to time I even use it.

This time I needed to rename a lot of files in some directory I had.

First thing to note is that these files are on a NAS.

No problem just do

text

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cd \\192.168.1.152\series

and you're on that drive.

That doesn't work with the normal commandline BTW.

So now we are there we can see we have bunch of files.

It is clear that these files don't say a lot about the contents, I will want to fix that. I want to prefix them all with Stargate. Easy just cd your way to that directory Stargate/SG1/Season 1 and do this.

text

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Dir *.mkv | rename-item -newname { "Stargate " + $_.Name}

Yep that's one line of code.

But darnit I have more than one season of Stargate, I have 10.

Not to worry just go to the Stargate/SG1 directory instead and do this.

text

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Get-ChildItem -recurse | Where {$_ -IS [IO.FileInfo]} | rename-item -newname { "Stargate " + $_.Name}

And done. Oh no, I made a misstake I also have Atlantis and Universe on there so I would better name them Stargate - SG1.

Not to worry I can just replace what I did before. Like this.

text

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Get-ChildItem -recurse | Where {$_ -IS [IO.FileInfo]} | rename-item -newname { -replace "Stargate ","Stargate - SG1 " }

And I'm done. Now to just do this for the 2 others and everything is a lot clearer from now on.

Happy powershelling people.

Original post blogged on LessThanDot.

Smalltalk

Christiaan Baes (chrissie1) — Sat, 08 Dec 2012 06:24:00 +0000

Introduction

A few days ago Demis Bellot (the creator of Servicestack) was talking about Smalltalk on twitter. A little discussion came about involving Alex Ullrich.

So my next mission was to learn a thing or two about smalltalk myself.

Installation

I tried two smalltalk IDE's. Squeak (which I couldn't get to work on Win8) and Dolphin X6 community edition.

So I stuck with Dolphin. And the installation is next, next, next and finish.

The beginning

So how does one learn Smalltalk, on starts with finding a good tutorial. And I found a very good one by Bitwise magazine.

Lesson 1 has Dolphin and Squeak in it but from Lesson 2 you can go to a dedicated Dolphin page(s).

Just follow that tutorial and you will be fine.

To be honest, smalltalk is weird. I have done a few languages in my time, lots of basic dialects (visual basic, turbobasic VBA, ...), lots of c dialects (C++, Java, C#, javascript, PHP, ...), COBOL, Delphi, and some I have forgotten what the syntax looks like. Smalltalk however is nothing like the previous languages.

It uses the comma to concatenate strings.

Code: smalltalk

'Hello',' World!'.

It uses the dot as a line-ending character.

It uses square brackets for blocks of code.

Code: smalltalk

1 timesRepeat: [Transcript clear.
Transcript show: 'Hello'; cr.
Transcript show: 'Hello2'; cr.].

It uses the space as a seperator character to define arrays.

Code: smalltalk

mixedlist := #( 'one' 2 (3 4 5) $6 ).

It uses capitalization to determine scope, variables starting with an uppercase letter are Global scope, variables with a lowercase are local to your workspace.

And there are many more things you will discover.

Learning something like smalltalk is really cool. It opens your eyes a bit.

Conclusion

Go ahead, download dolphin and follow the bitwise tutorial, you will learn something new if you have never tried smalltalk before.

Original post blogged on LessThanDot.

Kotlin and Maven

Christiaan Baes (chrissie1) — Mon, 03 Dec 2012 09:54:00 +0000

Introduction

Last week I asked if Spek was on a Maven repository so I could easily add it to my project and test it.
Someone who will remain anonymous (who still needs to wash my car) and runs the Spek project told me it wasn't and that I could be so nice to add it.

I know next to nothing about Maven, except that it exists. So I went on the Google and found... a lot of things that I didn't know about. But in the end I found this.

And that helped just a little.

Setting up Maven

Apparently everybody knows how to set up Maven but forget to tell how it is done.
So first of all I downloaded Maven 3.0.4 and then unzipped that in the Program files folder (x86). Then I had to add this E:\Program Files (x86)\apache-maven-3.0.4\bin to my Path in the System Variables whiyou can find in Control Panel -> System -> Advanced settings -> Environment variables. I also needed to add the system variable JAVA_HOME and set it to this E:\Program Files (x86)\Java\jdk1.7.0\jre or the path to your jre of your JDK.

You can also add the system variable M2_HOME and set it to this E:\Program Files (x86)\apache-maven-3.0.4 or not. You can choose to add it manually to your module too.

If you get this error

Error running kotlindeom [test]: No valid Maven installation found. Either set the home directory in the configuration dialog or set the M2_HOME environment variable on your system.

then the above did not work. In Intellij go to File -> Settings -> Maven and copy the Maven directory in the Maven home directory field.

And now Maven works with Intellij 12. Oh joy.

MavenModule

It is now time to make our project.

Make a new project and make it a Maven module.

use the quickstart archetype, or any other archetype since we are not going to use it anyway.

override the maven home directory if you did not set M2_HOME or if you so desire.

Now we can change the pom.xml file to this.

Code: xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 <a href="http://maven.apache.org/xsd/maven-4.0.0.xsd">">http://maven.apache.org/xsd/maven-4.0.0.xsd"></a>

<modelVersion>4.0.0</modelVersion>

<groupId>kotlindemos</groupId>
<artifactId>kotlindeom</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
<kotlin.version>0.1-SNAPSHOT</kotlin.version>
<junit.version>4.11</junit.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-stdlib</artifactId>
<version>${kotlin.version}</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>

<build>
<sourceDirectory>${project.basedir}/src/main</sourceDirectory>
<testSourceDirectory>${project.basedir}/src/test</testSourceDirectory>

<plugins>
<plugin>
<artifactId>kotlin-maven-plugin</artifactId>
<groupId>org.jetbrains.kotlin</groupId>
<version>${kotlin.version}</version>

<configuration/>
<executions>
<execution>
<id>compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>test-compile</id>
<phase>test-compile</phase>
<goals>
<goal>test-compile</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

<repositories>
<repository>
<id>jetbrains-all</id>
<url>http://repository.jetbrains.com/all</url>
</repository>
</repositories>

<pluginRepositories>
<pluginRepository>
<id>jetbrains-all</id>
<url>http://repository.jetbrains.com/all</url>
</pluginRepository>
</pluginRepositories>
</project>

If everything is well you should not see any red in there.

Does it work?

Now we can start adding our kotlin files in.

Create a package kotlin.kotlindemo in the main and remove the package java. Add a kotlin file to that and use this code.

Code: java

package demo

data class MyClass(val i : Int, val s : String)

Now add a kotlin.kotlindemo package to the test folder and add a kotlin file.

With this code.

Code: java

package demo.test

import demo.MyClass
import kotlin.test.assertEquals
import org.junit.Test as test
import kotlin.test.assertTrue
import kotlin.test.assertFalse

public class TestMyClass
{
test fun IfPropertyIIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals(1,c1.i)
}

test fun IfPropertySIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals("t",c1.s)
}

test fun If2MyClassesWithTheSamePropertiesAreEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(1,"t")
assertTrue(c1.equals(c2))
}

test fun If2MyClassesWithDifferentPropertiesAreNotEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(2,"t")
assertFalse(c1.equals(c2))
}

test fun IfToStringReturnsTheCorrectString()
{
val c1 = MyClass(1, "t")
assertEquals("MyClass(i=1, s=t)",c1.toString())
}
}

You might think this is the same class as in my previous blogpost but it isn't. My previous class was called testMyClass and by convention Maven only finds Test*, *Test or TestCase* classes. I found that out the hard way. Lucky me.

Anyway, your project should look like this.

And now when we open our Maven project view. we should see this.

you can now doubleclick on test and see the magic happen.

This should be the result.

5 tests run and none faild. Woohoo.

Conclusion

It took me a while to get it to work since I could not find Maven and IntelliJ for dummies and the Maven site is full of XML. But it works and I'm happy. Now on to Spek and getting the package into a repo, be afraid, be very afraid.

Original post blogged on LessThanDot.

Kotlin and testing

Christiaan Baes (chrissie1) — Sun, 02 Dec 2012 12:28:00 +0000

Introduction

When learning a language it is important to know how to write unittests for it. Most modern languages have testing built in. And Kotlin is no exception. Kotlin has the kotlin.test namespace that has all the asserts you need.

Configuration

You will find plenty of examples how to write tests with Kotlin but something was escaping me because my tests would not run.

Let's take our class.

Code: java

package demo

data class MyClass(val i : Int, val s : String)

uhm yeah.

Now lets try our first test.

Code: java

package demo.test

import demo.MyClass
import kotlin.test.assertEquals

public class tests
{
test fun IfPropertyIIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals(1,c1.i)
}
}

I was excpeting the above to run. It doesn't give a compilation error but the Intellij testrunner doesn't like it. So I was doing something wrong.

The thing I missed was that it also needs JUnit. You can get maven to download and install it.

And add this line to you import.

Code: java

import org.junit.Test as test

Now the intellij testrunner will like them and run them.

More tests.

And here are some more tests.

Code: text

package demo.test

import demo.MyClass
import kotlin.test.assertEquals
import org.junit.Test as test
import kotlin.test.assertTrue
import kotlin.test.assertFalse

public class tests
{
test fun IfPropertyIIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals(1,c1.i)
}

test fun IfPropertySIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals("t",c1.s)
}

test fun If2MyClassesWithTheSamePropertiesAreEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(1,"t")
assertTrue(c1.equals(c2))
}

test fun If2MyClassesWithDifferentPropertiesAreNotEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(2,"t")
assertFalse(c1.equals(c2))
}

test fun IfToStringReturnsTheCorrectString()
{
val c1 = MyClass(1, "t")
assertEquals("MyClass(i=1, s=t)",c1.toString())
}
}

But you can just as well do this.

Code: java

package demo.test

import demo.MyClass
import org.junit.Assert.assertEquals
import org.junit.Test as test
import org.junit.Assert.assertTrue
import org.junit.Assert.assertFalse

public class tests
{
test fun IfPropertyIIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals(1,c1.i)
}

test fun IfPropertySIsSetCorrectly()
{
val c1 = MyClass(1,"t")
assertEquals("t",c1.s)
}

test fun If2MyClassesWithTheSamePropertiesAreEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(1,"t")
assertTrue(c1.equals(c2))
}

test fun If2MyClassesWithDifferentPropertiesAreNotEqual()
{
val c1 = MyClass(1,"t")
val c2 = MyClass(2,"t")
assertFalse(c1.equals(c2))
}

test fun IfToStringReturnsTheCorrectString()
{
val c1 = MyClass(1, "t")
assertEquals("MyClass(i=1, s=t)",c1.toString())
}
}

Notice the difference?

Conclusion

Not sure if kotlin.test adds much. We can just as well use Junit directly, you need it anyway.

Original post blogged on LessThanDot.

Your queue is not threadsafe and sometimes that can give unwanted sideeffects

Christiaan Baes (chrissie1) — Wed, 28 Nov 2012 06:58:00 +0000

Introduction

For one of my projects I needed to show the 30 last messages to the user. I was not interested in keeping these messages. So I decided to use a queue. The messages come from different sources and different threads.

And the different threads bit is important.

The queue

Here is what can happen if you use the not threadsafe queue.

Let's take this little example.

Code: vbnet

Imports System.Threading

Module Module1
Private _queue As Queue(Of String)
Private _count As Integer

Sub Main()
Console.WriteLine("Not concurrent threads")
_count = 0
Dim t As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessage(x))))
Dim t2 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessage(x))))
Dim t3 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessage(x))))
Dim t4 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessage(x))))
t.Start()
t2.Start()
t3.Start()
t4.Start()
Do While _count < 4

Loop
_count = 1
For Each q In _queue.Reverse.ToList
Console.WriteLine(_count & ". " & q)
_count += 1
Next
Console.ReadLine()
End Sub

Public Sub Addmessages(ByVal action As Action(Of String))
For x = 1 To 1000000
action.Invoke("test")
Next
_count += 1
End Sub

Public Sub AddMessage(message As String)
If _Queue Is Nothing Then
_queue = New Queue(Of String)(1000000)
End If
If Not String.IsNullOrEmpty(message) Then
_Queue.Enqueue(message)
End If
Dim result As String
If _queue.Count > 10 Then
_queue.Dequeue()
End If
End Sub

End Module

That is 4 threads that add 1000000 messages to the queue at an alarming rate. And I only want to keep the last 10 messages in my queue.

The result.

128683. test
128684. test
128685. test
128686. test
128687. test
128688. test
128689. test
128690.
128691. test
128692. test
128693. test
128694. test
128695. test
128696. test
128697. test
128698. test
128699. test
128700. test
128701. test
128702. test
128703. test
128704. test

Those are only the last ones. There are 128704 elements in our queue and some are empty. Not sure how I get the empty ones but I guess it must be somewhere between an enqueue and a dequeue.

Anyway the results are not what we desire.

And of course now I could start adding blocks here and there to make sure the enqueue and dequeue are atomic operations and what not but Since .Net 4.0 there are Concurent collections and they are threadsafe by design. Lucky us.

The concurrent queue

We can simply change our code to this.

Code: vbnet

Imports System.Collections.Concurrent
Imports System.Threading

Module Module1
Private _concurrentQueue As ConcurrentQueue(Of String)
Private _count As Integer

Sub Main()
Console.WriteLine("concurrent threads")
_count = 0
Dim t5 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessageConcurrently(x))))
Dim t6 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessageConcurrently(x))))
Dim t7 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessageConcurrently(x))))
Dim t8 As New Thread(New ParameterizedThreadStart(Sub() Addmessages(Sub(x) AddMessageConcurrently(x))))
t5.Start()
t6.Start()
t7.Start()
t8.Start()
Do While _count < 4

Loop
_count = 1
For Each q In _concurrentQueue.Reverse.ToList
Console.WriteLine(_count & ". " & q)
_count += 1
Next
Console.ReadLine()
End Sub

Public Sub Addmessages(ByVal action As Action(Of String))
For x = 1 To 1000000
action.Invoke("test")
Next
_count += 1
End Sub

Public Sub AddMessageConcurrently(message As String)
If _concurrentQueue Is Nothing Then
_concurrentQueue = New ConcurrentQueue(Of String)()
End If
If Not String.IsNullOrEmpty(message) Then
_concurrentQueue.Enqueue(message)
End If
Dim result As String
If _concurrentQueue.Count > 10 Then
_concurrentQueue.TryDequeue(result)
End If
End Sub

End Module

And now the result is.

concurrent threads
1. test
2. test
3. test
4. test
5. test
6. test
7. test
8. test
9. test
10. test

And that is exactly what I expected.

Conclusion

There is a namespace in .Net since 4.0 that contains threadsafe collections. And it is there for you to use. I would however not overuse it since I expect the blocking to have an effect on performance.

Original post blogged on LessThanDot.

Kotlin: val and var

Christiaan Baes (chrissie1) — Sun, 25 Nov 2012 06:46:00 +0000

Introduction

I am now using kotlin plugin 0.4.221 while I was using 0.4.214 just yesterday.

In the last couple of weeks I started dabbling in kotlin a bit and wrote a first blogpost about the data class, because the data class was a new concept that I have not yet encountered in one of the many programminglanguages I have used over the years. But that probably means I have just been using the wrong ones all these years. Another new concept for me was the val keyword.

The val keyword tells the compiler that our object is immutable.

To val or not to val

So let's see what that means.

Let's make a data class with a val property and a var property.

Code: java

data class MyClass(var i : Int, val s : String)

And now let's try and use our class, like this.

Code: java

fun main(args : Array<String>) {
val c1 = MyClass(1,"t")
c1.i = 2
c1.s = "s"
}

you will get an error on the c1.s = "s" line because s is immutable and has been set in the constructor.

You might have noticed that we instantiated our class with the val keyword as well. this means you can no longer assign another instance to it..

So when I try this.

Code: java

c1 = MyClass(1,"s")

I will get the same error as before.

So if you want to change an immutable class then you will have to create another instance and start passing that along.

Code: java

data class MyClass(val i : Int, val s : String)

fun main(args : Array<String>) {
val c1 = MyClass(1,"t")
println(c1.i)
println(c1.s)
val c2 = MyClass(c1.i,"s")
println(c2.i)
println(c2.s)
}

Conclusion

Immutability is desirable a lot of the time, it protects you from unwanted side effects.

According to wikipedia.

Immutable objects are often useful because they are inherently thread-safe.[1] Other benefits are that they are simpler to understand and reason about and offer higher security than mutable objects.

Original post blogged on LessThanDot.

Kotlin the data class and the class

Christiaan Baes (chrissie1) — Sat, 24 Nov 2012 06:41:00 +0000

Introduction

Over the last few weeks I have been playing around with Kotlin.

First let me tell you that it can be a bit frustrating because Kotlin is far from a finished product. It works on an EAP version of IntelliJ with nightly builds of the plugin. So you are bound to have version that don't work. I had 2 of those over the last week. But it now works with IntelliJ 123.4 and kotlin plugin 0.4.214.

And that things still change can be proven by the fact that the samples use tuples while tuples have been removed and replaced by data classes. So you can expect to find errors in the documentation and in the samples on github.

But we are here to learn. And I found the concept of the data class very intriguing.

The class

in kotlin you can define a class like this.

Code: java

class MyClass(val i : Int, val s : String)

That's a class with two properties named i and s.

And we can read out all the usual methods like this.

Code: java

fun main(args : Array<String>) {
val c1 = MyClass(1,"t")
val c2 = MyClass(1,"t")
val c3 = MyClass(2,"t")
println(c1.toString())
println(c1.equals(c2))
println(c1.equals(c3))
println(c1.equals(c1))
println(c1.hashCode())
println(c2.hashCode())
println(c3.hashCode())
println(c1.i)
println(c1.s)
}

with this as the result.

demo.MyClass@337d0f
false
false
true
3374351
21356612
8831815
1
t

That's how I would expect any class to behave even in .Net and Java. Nothing special.

The data class

Now lets add the keyword data in front of it.

Code: java

data class MyClass(val i : Int, val s : String)

and run our code again.

MyClass(i=1, s=t)
true
false
true
147
147
178
1
t

the result is completely different. c1 and c2 are the same the tostring is differnt and the hashcodes are different.

The data class behaves as a DTO.

But the data class is also a tupple.

Which we can demonstrate by adding these two lines to our main.

Code: java

println(c1.component1())
println(c1.component2())

Which will now give us the following output.

MyClass(i=1, s=t)
true
false
true
147
147
178
1
t
1
t

Just like a tupple.

So tostring, equals and hashcode are autoimplemented for a data class and based on the properties you provide.

But you can also override that behavior if you want.

Code: java

data class MyClass(val i : Int, val s : String)
{
fun equals(val obj : Any) : Boolean {
return (obj as MyClass).s.equals(s)
}

fun hashCode() : Int
{
return s.hashCode()
}

fun toString() : String {
return s.toString()
}
}

with this as the result.

t
true
true
true
116
116
116
1
t
1
t

Cool.

Conclusion

I very much like the data class and it would come in handy in many other languages.

Original post blogged on LessThanDot.

Json.Net 's JObject to dynamic in VB.Net

Christiaan Baes (chrissie1) — Sun, 11 Nov 2012 12:44:00 +0000

In my previous post I showed you how to get an object from a call to a SignalR method.

That call on the client side returns a Json.Net JObject. This is dynamic object.

However, the implementation of this object is not very VB.Net friendly.

If you try this.

Code: vbnet

Imports System.Runtime.CompilerServices
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
Imports Microsoft.AspNet.SignalR.Client.Hubs

Module Module1

Sub Main()
Dim connection = New HubConnection("http://localhost:50865")

Dim plants = connection.CreateHubProxy("Plants")

plants.On(Of String)("addMessage", Sub(data) Console.WriteLine(data.ToString()))

connection.Start().Wait()

Dim line As String = Nothing
Console.WriteLine("type the id + enter to send, type exit + enter to exit.")
While line <> "exit"
line = Console.ReadLine()
plants.Invoke(Of Object)("GetPlant", line).ContinueWith(Sub(data)
If data.Result IsNot Nothing Then
Console.WriteLine(data.Result.ToString)
Dim result = data.Result
Console.WriteLine(result.Id)
Console.WriteLine(result.Genus)
Console.WriteLine(result.Species)
For Each commonName In result.CommonNames
Console.WriteLine(commonName)
Next
Else
Console.WriteLine("No plant with that id.")
End If
End Sub)
End While
End Sub

End Module

You will get an exception on result.Id

System.MissingMemberException was unhandled by user code
HResult=-2146233070
Message=Public member 'Id' on type 'JObject' not found.
Source=Microsoft.VisualBasic
StackTrace:
at Microsoft.VisualBasic.CompilerServices.Symbols.Container.GetMembers(String& MemberName, Boolean ReportErrors)
at Microsoft.VisualBasic.CompilerServices.NewLateBinding.ObjectLateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
at Microsoft.VisualBasic.CompilerServices.NewLateBinding.FallbackGet(Object Instance, String MemberName, Object[] Arguments, String[] ArgumentNames)
at CallSite.Target(Closure , CallSite , Object )
at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
at Invoker(CallSiteBinder , Object , Object[] )
at Microsoft.VisualBasic.CompilerServices.IDOUtils.CreateRefCallSiteAndInvoke(CallSiteBinder Action, Object Instance, Object[] Arguments)
at Microsoft.VisualBasic.CompilerServices.IDOBinder.IDOGet(IDynamicMetaObjectProvider Instance, String MemberName, Object[] Arguments, String[] ArgumentNames, Boolean[] CopyBack)
at Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
at SignalRConsole.Module1._Lambda$__2(Task`1 data) in E:\Users\christiaan\Documents\Visual Studio 2012\Projects\SignalRTesting\SignalRConsole\Module1.vb:line 25
at System.Threading.Tasks.ContinuationTaskFromResultTask`1.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
InnerException:

The problem is the LateGet. But you can found out all about why this is a problem for VB.Net in the following post by Matthew Doig.

And none of the Json.net converters can solve this for us.

But we can use another library that does work with VB.Net.

And it's called JSonFX. Just add it to your project via Nuget and then we can change our code to this.

Code: vbnet

Imports System.Runtime.CompilerServices
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
Imports Microsoft.AspNet.SignalR.Client.Hubs

Module Module1

Sub Main()
Dim connection = New HubConnection("http://localhost:50865")

Dim plants = connection.CreateHubProxy("Plants")

plants.On(Of String)("addMessage", Sub(data) Console.WriteLine(data.ToString()))

connection.Start().Wait()

Dim line As String = Nothing
Console.WriteLine("type the id + enter to send, type exit + enter to exit.")
While line <> "exit"
line = Console.ReadLine()
plants.Invoke(Of Object)("GetPlant", line).ContinueWith(Sub(data)
If data.Result IsNot Nothing Then
Console.WriteLine(data.Result.ToString)
Dim reader = New JsonFx.Json.JsonReader()
Dim result = reader.Read(data.Result.ToString)
Console.WriteLine(result.Id)
Console.WriteLine(result.Genus)
Console.WriteLine(result.Species)
For Each commonName In result.CommonNames
Console.WriteLine(commonName)
Next
Else
Console.WriteLine("No plant with that id.")
End If
End Sub)
End While
End Sub

End Module

Now our result will be.

type the id + enter to send, type exit + enter to exit.
1
{
"Id": 1,
"Genus": "Fagus",
"Species": "Sylvatica",
"CommonNames": [
"Common Beech"
]
}
Someone requested id: 1
1
Fagus
Sylvatica
Common Beech

Which is ultra cool.

Original post blogged on LessThanDot.