Russell Smithers"Experience is the only teacher we have" – Swami Vivekananda

Hello,

I originally started to write this for a post in a closed, Open University forum for TT381 (Open Source Development Tools, part of Web Applications Development qualification). I wanted to widen the audience. So apologies if it reads a little odd for a web post. I don’t have time to rewrite it.

I was just wondering what version control system (or systems) you use at work, and if you have thought about how your ways of working, branching and migration of changes would map onto a DVCS, like GIT if your using a VCS like Subversion of CVS. Or maybe how a VCS would be used if you use a DVCS and had to switch back).

Last night I went to bed pondering how we do things at work using Subversion, and how I would be able to use GIT to achieve the same. We have a very prescribed way of managing changes, including when we move them. (Testing and other parts of life cycle need to be synced)

I had to setup the way we use subversion to accomplish the way the company wanted to work. I know it’s the simplest way we could setup Subversion, but it’s slightly unconventional. We don’t merge al changes back to a main trunk, and if I was to spend the time explaining you would see why.We have to use a very targeted management change, so working on a branch and merging it back to main trunk doesn’t work for a few reasons. We have to be able to tailor whats on a branch.

The up shot is, having proved for myself the way we use Subversion at work is probably the only way we could use it. This is based on considering the existing way is simple and effective, and that a better way of doing it would involve more complexity, and therefore more understanding and commitment from the rest of the team.

We could map the same way of working onto a DVCS, in this case GIT, very easily. And it would make migration of change operations allot quicker, simpler and easier. It would be easy to use a main trunk rather than successive branches.

So, my question is, would using a DVCS like GIT (pick your own poison here, Mercurial etc), improve your way of software development?

The only problem we would have is, that we have to have a custom made interface for our version control system, and switching is an effort. Creation of a new front end would take too much development time out and we have too many real world projects. Then the planning and switch over would incurr another over head and affect the whole team. So at least whilst writing the new GUI it’s just me offline for projects. Then there is the bedding in and ironing out of issues once we have switched. Of course not forgetting all that training.

Russell

“The Daily WTF” (TDWTF) website is one that most people I know probably wouldn’t want to read on a daily basis, but I follow it with the help of an RSS feed. However, there are two stories on the TDWTF that I have to share, because you don’t need to be techy or geek to understand them, and they are fab!

The Proven Fix – I like this because it goes to show that actually testing something is 110% better than working through some intelectual process that suggests it might work!

Lacking Knowledge Essentials – Just when you think a company is so bad they will go out of business, they work with another business who makes them look organised! lol fantastic!

Here are three web based resources for people who use KCML, KFORM and KDB.

1. A group on LinkedIn called The KCML Programming Language
2. Forums for the entire KCML tool set; www.kcmlhelp.co.uk
3. A group on Facebook; http://www.facebook.com/group.php?gid=83435884572

Subversion is used for version control and, having recently set up a subversion repository, I wanted to share the experience. Previously my experience of versioning was SCCS and CVS, both of these systems do the job, but Subversion is very easy to use and setup. Over the last few months I have used it extensively and become very knowledgeable about it. I would recommend Subversion to any one needing version control, I use it for source files, but it would be equally good for any thing else, it handles binary and text files so there is no limit.

Here are some links should you want to find out more;

Subversion website – subversion.tigris.org
Subversion forums – www.svnforum.org

Calculator Class

Description

Provides the graphical user interface of the calculator. Looking at the code you will see the method;

public void actionPerformed(ActionEvent e)

which is the central hub of the Calculator, it is the point at which the user actions (events) are turned into sequences of actions that result in calculations being performed, and their result being shown to the user.

Source

/*
 * Calculator
 *
 * Russell Smithers
 * 26 October 2006
 *
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Calculator implements ActionListener
{
    // Display area references
    public JPanel mainPanel, selectPanel, displayPanel, actionPanel, memoryPanel;
    private JLabel displayScreen;

    // Calculation references and variables
    Calculation currentCalc;
    StringBuilder screenValue;
    double value;
    char valueInput;

    /**
     * Create a GUI Calculator - sets up swing with relevant controls
     */
    public Calculator()
    {
        // Main panel that holds all controls
        mainPanel = new JPanel();
        mainPanel.setLayout(new GridLayout(0,2));
        mainPanel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));

        // Screen areas
        this.displayPanel = this.addPanel("Result",0,0);
        this.memoryPanel = this.addPanel("Memory",0,1);
        this.selectPanel = this.addPanel("Keypad",0,3);
        this.actionPanel = this.addPanel("Operations",0,1);

        // Number buttons
        for (int button=9; button>=0; button--)
        { this.addButton(selectPanel, "" + button); }
        this.addButton(selectPanel, ".");
        this.addButton(selectPanel, "Clr");

        // Operation buttons
        this.addButton(actionPanel, "+");
        this.addButton(actionPanel, "-");
        this.addButton(actionPanel, "/");
        this.addButton(actionPanel, "*");
        this.addButton(actionPanel, "=");

        // Output area
        displayScreen = new JLabel();
        this.displayPanel.add( displayScreen );
        screenValue = new StringBuilder();

        currentCalc = new Calculation();
    }

    /**
     * Event handler which handles all input
     */
    public void actionPerformed(ActionEvent e)
    {
        // System.out.println("Button pressed: " + e.getActionCommand() );
        String valueOrig = e.getActionCommand();
        this.valueInput = valueOrig.charAt(0);

        if ( Calculation.operationValid(valueInput) )
        {
            try
            {
                this.value = Double.valueOf(screenValue.toString()).doubleValue();
            }
            catch(Exception anError)
            {
                this.value = 0.0;
            }
            currentCalc.calculate( this.value, valueInput);
            this.updateDisplay();
        }
        else
        {
            if ( Character.isDigit(this.valueInput) || this.valueInput == '.')
            {
                screenValue.append( this.valueInput );
                this.displayScreen.setText( screenValue.toString() );
            }
            else
            {
                switch(this.valueInput)
                {
                    case 'C': currentCalc.setValue(0.0);
                }
                this.updateDisplay();
            }
        }

    }

    /**
     * Set calculator value
     */
    public void updateDisplay()
    {
        this.displayScreen.setText( Double.toString(currentCalc.getValue()) );
        this.screenValue = new StringBuilder();
    }

    /**
     * Add a button with an ActionListener and then add it to a panel
     */
    private void addButton(JPanel p, String value)
    {
        JButton tempButton = new JButton(value);
        tempButton.addActionListener(this);
        p.add(tempButton);
    }

    /**
     * Adds a new panel the main container panel and sets default decoration
     */
    private JPanel addPanel(String title, int x, int y)
    {
        JPanel tempPanel = new JPanel();

        // Set GridLayout is we have relevant values to use on
        if ( (x > 0) || (y >0) )
        { tempPanel.setLayout(new GridLayout(x,y)); }

        // Set the panel decoration
        tempPanel.setBorder(BorderFactory.createCompoundBorder(
                BorderFactory.createTitledBorder(title), BorderFactory.createEmptyBorder(5,5,5,5)));

        // Add ths panel to the main one
        this.mainPanel.add(tempPanel);

        return tempPanel;
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI()
    {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        Calculator calcy = new Calculator();

        //Create and set up the window.
        JFrame calculatorFrame = new JFrame("Calculator v1.0 (rsmithers.net)");
        calculatorFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        calculatorFrame.setContentPane(calcy.mainPanel);

        //Display the window.
        calculatorFrame.pack();
        calculatorFrame.setVisible(true);
    }

    /**
     * Entry point for Calculator program
     */
    public static void main(String[] args)
    {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowGUI();
            }
        });
    }
}

Introduction

This is a Standard Deviation calculator, written in C# .NET, it shows the workings out. Obviously Excel will calculate standard deviation if you just need a final figure.

Purpose 

This application is aimed at those who want to understand how Standard Deviation is worked out, and can be useful in checking their calculations. You may find the following explanation useful; http://www.gcseguide.co.uk/standard_deviation.htm.

Quick Start Instructions

To use this application simple enter your figures into the 1st column on the grid, as each number is entered the standard deviation is recalculated. You can also use the import or past (Edit>Past) options to retrieve figures without having to enter them by hand.

Installation 

Please visit standard deviation release area to install onto your computer, or run it from the web.