Software Salariman

Wrote an article about converting an simple Java program to C# and Windows Forms and discussed development features in Visual Studio C# 2008 Express.

This blog entry is used for discussion, if any.

Labels: CSharp, DotNet, Programming

link posted by Kam-Hung Soh @ 10:02 PM   0 comments
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In an earlier article, we used an associative array to group words with the same property (in this case, the same set of letters) to find anagrams. While that solution worked, it seemed to me that there should be an easier solution using the Group-Object cmdlet.

> "add", "dad", "dam", "mad", "made", "madam", "set" | group { $_.toCharArray() | sort-object }

Count Name                      Group
----- ----                      -----
    2 a d d                     {add, dad}
    2 a d m                     {dam, mad}
    1 a d e m                   {made}
    1 a a d m m                 {madam}
    1 e s t                     {set}

Looking good, so let's try a bigger set of words in a file:

> get-content test.txt | group-object { $_.toCharArray() | sort-object }

Count Name                      Group
----- ----                      -----
    2 a d d                     {test.txt, test.txt}
    2 a d m                     {test.txt, test.txt}
    1 a d e m                   {test.txt}
    1 a a d m m                 {test.txt}
    1 e s t                     {test.txt}

That's mighty weird. For some reason, the group has the name of the file rather than the actual word while the signature in the Name column is computed correctly. Is the problem to do with the expression for the group-object? Let's try a simpler expression:

> get-content test.txt | group-object { $_.length }

Count Name                      Group
----- ----                      -----
    5 3                         {test.txt, test.txt, test.txt, test.txt...}
    1 4                         {test.txt}
    1 5                         {test.txt}

It's very puzzling and it seems like group-object was treating each file rather than each word as an input. But then, why is the expression being computed for each word?

Even stranger is when you assign the contents of a file to a variable and get the same result!

> $l = get-content test.txt
> move-item test.txt test2.txt #Ensure original file is no longer available.
> $l | group-object {$_.length}

Count Name                      Group
----- ----                      -----
    5 3                         {test.txt, test.txt, test.txt, test.txt...}
    1 4                         {test.txt}
    1 5                         {test.txt}

In this case, I would have thought that group-object would operate on a list of words and not refer to the original file.

Later … .Net has a function string[] ReadAllLines() that returns an array of strings, so the following works a treat:

> [System.IO.File]::ReadAllLines("C:\temp\download\doc\language\test.txt") | group-object {$_.ToCharArray() | sort-object}

Count Name                      Group
----- ----                      -----
    2 a d d                     {add, dad}
    2 a d m                     {dam, mad}
    1 a d e m                   {made}
    1 a a d m m                 {madam}
    1 e s t                     {set}

At least PowerShell's integration with the .Net Framework makes it possible to solve a problem if the pre-defined cmdlets don't work as you expect.

2-Jan-2008. If you're using PowerShell 2.0 CTP, the Get-Content version works.

Labels: DotNet, PowerShell

link posted by Kam-Hung Soh @ 8:19 AM   0 comments
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The Python language has been ported to two major virtual machine platforms: IronPython for Microsoft .Net and Jython for Java. To get a flavour of these implementations, here are two Hello World scripts that open a window containing a label and a button.

IronPython Hello World Window

import clr
clr.AddReference("System.Drawing")
from System.Drawing import ContentAlignment, Size
clr.AddReference("System.Windows.Forms")
from System.Windows.Forms import Button, FlowLayoutPanel, Form, Label

p = FlowLayoutPanel()
p.Controls.Add(Label(Text="A label:", Size=Size(50,20), TextAlign=ContentAlignment.BottomLeft))
p.Controls.Add(Button(Text="Press Me"))
f = Form(Text="Hello World", Size=Size(160,70))
f.Controls.Add(p)
f.ShowDialog()

Jython Hello World Window

# Jython Hello Window
from java.awt import FlowLayout
from javax.swing import JButton, JFrame, JLabel

f = JFrame("Hello", defaultCloseOperation=JFrame.DISPOSE_ON_CLOSE, size=(170,70), layout=FlowLayout())
f.add(JLabel("A label:"))
f.add(JButton("Press Me"))
f.show()

Mini Observations

• IronPython makes loading the .Net libraries explicit by using the clr module.
• Both implementations allow setX functions in object constructor's argument list.

Labels: DotNet, Java, Python

link posted by Kam-Hung Soh @ 8:00 PM   0 comments
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