In working out a tricky design issue surrounding the usage of the Visitor pattern, I stumbled upon the related Double Dispatch pattern/mechanism.

In short, double dispatch, when implemented, allows an object - a "dispatcher" - to delegate method calls based on the runtime type or types involved in the interaction.

The two core problems with visitor are that:

1. You must have access to the visitable object to implement an IVisitable interface.  Often times, when dealing with binary code references, this is not an option.
2. Each visitor must implement IVisitor, regardless of whether all of the Visit() interactions make any sense.  This means that if there are 10 concrete IVisitable classes, then each IVisitor must implement 10 Visit() methods that support each of the concrete classes, even if the particular IVisitor has no valid operations on a given IVisitable.

I suppose point number 1 is not really a constraint, it's just that it's a criterion for a by-the-book visitor pattern implementation.  But point number 2 is a really sticky situation since in many cases, not all of the IVisitor concrete classes should support all of the IVisitable concrete classes.  Of course we could just add a blank method stub, even for operations that don't make sense, but that just seems like bloat and a maintenance nightmare.

The key in understanding the use of double dispatch is to understand the core issue with the Visitor pattern.  We want the visitor to perform different operations based on the runtime type passed into a call to an abstract Visitor base class.  Unlike method overloading, which relies on compile time types to determine the method to invoke, we want the code to decide which method to invoke based on the runtime type of the object being passed in.

Ideally, we could have a scenario like this:

public class Program {
    private static void Main(string[] args) {
        Collection<AbstractVisitor> visitors 
			= new Collection<AbstractVisitor>();
        Collection<Pet> pets = new Collection<Pet>();

        pets.Add(new Fish());
        pets.Add(new Dog());

        visitors.Add(new Feeder());
        visitors.Add(new Walker());

        // Visit each of the pets.
        foreach (Pet pet in pets) {
            foreach (AbstractVisitor visitor in visitors) {
                visitor.Visit(pet);
            }
        }
    }
}

/// <summary>
/// Abstract base class for visitors.
/// </summary>
public abstract class AbstractVisitor {
    public abstract void Visit(Pet pet);
}

/// <summary>
/// Concrete visitor, a pet feeder.
/// </summary>
public class Feeder : AbstractVisitor {
    public void Visit(Dog dog) {
        // Feed the dog
        dog.Visitors.Add("Fed the dog");
    }

    public void Visit(Fish fish) {
        // Feed the fish
        fish.Visitors.Add("Fed the fish");
    }
}

/// <summary>
/// Concrete visitor, a pet walker.
/// </summary>
public class Walker : AbstractVisitor {
    public void Visit(Dog dog) {
        dog.Visitors.Add("Walked the dog");
    }

    // Fish can't be walked!
}

But this code doesn't work!  Both Walker an Feeder must now implement Visit(Pet pet) like so:

/// <summary>
/// Abstract base class for visitors.
/// </summary>
public abstract class AbstractVisitor {
    public abstract void Visit(Pet pet);
}

/// <summary>
/// Concrete visitor, a pet feeder.
/// </summary>
public class Feeder : AbstractVisitor {
    // Yucky if block...
    public override void Visit(Pet pet) {
        if(pet is Dog) {
            Visit(pet as Dog);
        }
        if(pet is Fish) {
            Visit(pet as Fish);
        }
    }
    
    public void Visit(Dog dog) {
        // Feed the dog
        dog.Visitors.Add("Fed the dog");
    }

    public void Visit(Fish fish) {
        // Feed the fish
        fish.Visitors.Add("Fed the fish");
    }
}

This is a less than desirable situation since for every new pet type we introduce, we need to introduce another entry in the if-else block. Yuck. 

While there were many articles on how to implement double dispatch in C# using various techniques, by far, the simplest implementation that I found was one by Anthony Cowley.

So let's see how our code would look using this technique (I'll omit the implmentation of the abstract visitor class for now):

public class Program {
    private static void Main(string[] args) {
        Collection<AbstractVisitor> visitors 
			= new Collection<AbstractVisitor>();
        Collection<Pet> pets = new Collection<Pet>();

        pets.Add(new Fish());
        pets.Add(new Dog());

        visitors.Add(new Feeder());
        visitors.Add(new Walker());

        // Visit each of the pets.
        foreach (Pet pet in pets) {
            foreach (AbstractVisitor visitor in visitors) {
                visitor.Visit(pet);
            }
        }

        // Check the results.
        foreach(Pet pet in pets) {
            Console.Out.WriteLine(pet.GetType().Name);
            foreach(String note in pet.Visitors) {
                Console.Out.WriteLine("\t{0}", note);
            }
        }
    }
}

/// <summary>
/// Concrete visitor, a pet feeder.
/// </summary>
public class Feeder : AbstractVisitor {
    public void Visit(Dog dog) {
        // Feed the dog
        dog.Visitors.Add("Fed the dog");
    }

    public void Visit(Fish fish) {
        // Feed the fish
        fish.Visitors.Add("Fed the fish");
    }
}

/// <summary>
/// Concrete visitor, a pet walker.
/// </summary>
public class Walker : AbstractVisitor {
    public void Visit(Dog dog) {
        dog.Visitors.Add("Walked the dog");
    }

    // Fish can't be walked!
}

/// <summary>
/// Base class for pets.
/// </summary>
public abstract class Pet {
    private readonly Collection<string> visitors;

    public Collection<string> Visitors {
        get { return visitors; }
    }

    protected Pet() {
        visitors = new Collection<string>();
    }
}

/// <summary>
/// A pet fish.
/// </summary>
public class Fish : Pet {}

/// <summary>
/// A pet dog.
/// </summary>
public class Dog : Pet {}

When I run this program, I get the following output:

As expected, the dog was walked and fed, but the fish was only fed. Now we can go about adding pets to our heart's content and we won't be forced to add another Visit() method declaration. If there is no Visit() method implemented for a particular pet type, then nothing happens and the default implementation of Visit() on the abstract class handles it. The magic all happens in Cowley's implementation of AbstractVisitor:

/// <summary>
/// Abstract base class for visitors.
/// </summary>
public abstract class AbstractVisitor {
    private static readonly Dictionary<long, MethodInfo> dispatch;

    static AbstractVisitor() {
        dispatch = new Dictionary<long, MethodInfo>();

        foreach (Type t in Assembly.GetCallingAssembly().GetTypes()) {
            if (t.IsSubclassOf(typeof(AbstractVisitor))) {
                foreach (MethodInfo mi in t.GetMethods()) {
                    if (mi.Name == "Visit") {
                        ParameterInfo[] pars = mi.GetParameters();
                        if (pars.Length == 1) {
                            Int64 code = ((Int64)t.GetHashCode() << 32) +
                                pars[0].ParameterType.GetHashCode();
                            dispatch.Add(code, mi);
                        }
                    }
                }
            }
        }
    }

    public virtual void Visit(object pet) {
        Int64 hash = ((Int64)GetType().GetHashCode() << 32) + 
            pet.GetType().GetHashCode();
        if (dispatch.ContainsKey(hash)) {
            dispatch[hash].Invoke(this, new object[] { pet });
        }
        else {
            // This is our fallback functionality
            Console.WriteLine("Visiting object " + pet.ToString());
        }
    }
}

You may have spotted an issue here: since the Visit() method is virtual, the subclasses of AbstractVisitor aren't strictly forced to define a Visit() method of any sort nor is there a constraint that forces any implementation to have only one argument.  But this is just fine, since all of the classes must inherit from AbstractVisitor to participate in this pattern, it will also inherit the default implementation of Visit() which, conveniently, contains a fallback do-nothing behavior.

You can download the full source here: SimpleDoubleDispatchSample.zip (4.08 KB)

I also have a second sample that I modified from Cowley's code that uses singleton instances of the visitors and improved encapsulation of the dispatch lookup table.  I also modified the catch all virtual Visit() method to a call to another virtual method to allow subclasses to change the default implementation of the case that no specific Visit() is found: SimpleDoubleDispatchSample.2.zip (4.12 KB)

Once again, credit goes to Anthony Cowley for an excellent and simple implementation of double dispatch in C#. There were two others that I examined, namely one by Max Hajek (which actually generated IL) and one by Steve Love using Generics.  In both cases, I thought the solutions were far more complex than the actual problem that they tried to solve, though Max's solution seems far more powerful and may be more useful in some scenarios.

I've recently picked up my copy of Code Complete - 2nd Edition again after a long hiatus from it.  It's such a massive book that I think if you plan on reading it from front to back, it'll bore you to death and put you to sleep.  Of course, this is not to say that the book is bad - quite the opposite, the book is filled to the brim with knowledge that will benefit any level of developer - but that you have to approach it in a more "leisurely" manner.

The book itself is one of those that you can really just kind of jump in and out of the chapters (except for some of the early ones that should be digested together).

Some bits from Chapter 31 that I think really capture the essence of the book. 

McConnell opens with an excellent statement that succintly summarizes my infatuation with proper code structure, naming, and other seemingly "non-development" coding activities: it is a matter of personal pride in my work and the effort that I put forth to make the code legible:

“The visual and intellectual enjoyment of well-formatted code is a pleasure that few nonprogrammers can appreciate.  But programmers who take pride in their work derive great artistic satisfaction from polishing the visual structure of their code.” (P.729)

The chapter covers the importance of good formatting and layout, the psychological effects of good layout and formatting (such as easier to memorize code structure), and techniques to achieve good layout.

McConnell introduces the idea of “The Fundamental Theorem of Formatting” which says “good visual layout shows the logical structure of a program” (P.732)

He quotes Elliot Soloway and Kate Ehrlich in their studies:

“…there is a psychological basis for writing programs in a conventional manner: programmers have strong expectations that other programmers will follow these discourse rules.  If the rules are violated, then the utility afforded by the expectations that programmers have built up over time is effectively nullified."  (P.733)

This is in alignment with the ideals of best practices.  The core concept is to have a codebase that exudes familiarity even to first time readers.  McConnell emphasizes the importance of the human aspect of coding:

“The smaller part of the job of programming is writing a program so that the computer can read it; the larger part is writing it so that other humans can read it.” (P.733)

Indeed, writing code so that the machine can read it is easy: the compiler, IDE, and development tools like ReSharper will tell you when the machine can’t read it.  Writing code so that other humans can read it is a true challenge since there is no one to confirm your view of the code or structure (without a well defined code review practice or pair programming). 

In that sense, writing code is not so different than writing in general.  Using shorthand is always the fastest ways to write little notes for oneself, but when composing a written work that others must consume, there are certain conventions that people come to expect: proper spacing, proper usage of punctuation, proper grammar, and the usage of paragraphs to delineate discrete bodies of text – these details all help to make the text more readable from a mechanical perspective.

While code is certainly not literature (well, not to most normal people anyways ), there are similar traits in elegant code structure and elegant prose: it is simple, clear, concise, and expressive.  It might follow a pattern (rhyming, iambic pentameter, etc.) that gives it a flow.

Soloway and Ehrlich’s studies concluded that:

“The results point out the fragility of programming expertise: advanced programmers have strong expectations about what programs should look like, and when those expectations are violated—in seemingly innocuous ways—their performance drops drastically.” (P.735)

They cite examples where advanced chess players showed a marked increase in ability to memorize chess pieces arranged in “standard” or common scenarios over novice players, but demonstrated no increased ability when the pieces were arranged in a random fashion.  The conclusion is that familiarity increases the ability to internalize and process an otherwise abstract structure (or in this case, arrangement of chess pieces).

Of course, it’s not all just fluff and “nice to haves”, right?  McConnell raises an interesting observation that:

“The information contained in a program is denser than the information contained in most books.  Whereas you might read and understand a page of a book in a minute or two, most programmers can’t read and understand a naked program listing at anything close to that rate.  A program should give more organizational clues than a book, not fewer."

This makes the argument clear for commenting, proper and consistent application of white space, and using descriptive rather than short names (see Framework Design Guidelines for more coverage on that).  For example (and I’ve never understood this one), the use of “itm” instead of typing “item” or “tsk” instead of “task” or the use of “d” to declare a local variable instead of “document”.  One letter makes the code much more readable and much easier to process for another human reader of the code.

McConnell also makes a very good case for how code should be structured to reduce the complexity of the visual layout.  He gives a good abstract comparison on page 747.  These are small items which increase the readability of the code in very subversive ways; you probably never think about such details actively, but when processing a page of code, little details like indentation probably have a strong effect on your ability to understand the purpose and nature of the code.  More importantly, when other humans have to process your code, these little details, taken in cumulative, could mean the difference between a day of ramp up and a week of ramp up time.

Of course, McConnell does acknowledge that in many cases, such matters of style are borderline “religious”.  But from an objective perspective:

“…it’s clear that some forms of layout are better than others.  Good programmers should be open-minded about their layout practices and accept practices proven to be better than the ones they’re used to, even if adjusting to a new method results in some initial discomfort.” (P.735)

Definitely a book that deserves some shelf space on any developer's desk (edit: or nightstand ).

One interesting issue that I just solved involved how to specify the location of the database file for a SQL Server Compact Edition 2005 connection string in a .Net add-in for Microsoft Office.

You see, when the add-in starts, it sets the context directory as the user's documents directory, which of course, makes it impossible to enter a configuration string for the data source of the connection string.

It works fine if the directory is hard coded - which is what I did for testing purposes initially, but of course, when I switched over to XP64, this broke as on XP64, the program is installed to "Program Files (x86)".

The solution lies buried in Microsoft's SQL CE documentation: there's a note that you should use a special token with the connection string like so:

<connectionStrings>
	<add name="ClientDatabase" 
		connectionString="Data Source=|DataDirectory|\data-file.sdf"
		providerName="Microsoft.SqlServerCe.Client" />
</connectionStrings>

The token needs to be included exactly as entered "|DataDirectory|". So how is this token replaced? In the static constructor of my Connect class that was autogenerated by Visual Studio, I added the following code:

/// <summary>
/// Initializes the logging subsystem for the <see cref="Connect"/> class.
/// </summary>
static Connect() {
	string path = Assembly.GetExecutingAssembly().Location;
	path = path.Substring(0, path.LastIndexOf('\\'));

	// Set the DataDirectory for the SQL Server CE connection string.
	AppDomain domain = AppDomain.CurrentDomain;
	domain.SetData("DataDirectory", path);
}

So this morning, a FedEx Express (redundant?) truck showed up at my front door promptly at 9:00 to deliver a little bundle of joy: a new workstation.

For as long as I've worked, I don't think I've ever received a new development machine from any of the companies I've worked for.  To cope with the invariably crappy, last gen machines that I've been assigned, I've always ended up buying my own.  I bought my own laptop after a few months suffering on an NT4 workstation with something like an 4 GB harddrive and only 100 MB were left for me to work with (this was in 2003, mind you).  I bought my own desktop (a screamer of a machine in its own right) after my laptop became too outdated to handle the resource hungry 2005 suite of software and servers from Microsoft.

The importance of good hardware can't be emphasized enough.  Fast hardware helps shorten compile times, helps shorten debugging cycles by offering better runtime performance, helps shorten development times by allowing for more installed tools (think ReSharper), and I think, in the big picture, help reduce developer stress and frustration.

As trivial a gesture as this may seem, for the first time, I feel appreciated and I feel like my employer takes my job and tasks seriously.  It's a truly special moment  It's as if he understands my pain (well, not so much mine since my machine is less than a year old (dual core @ 3.2GHz, 4GB RAM, 3x10K RPM HDs), but my pain in working with the rest of the team who are still on first gen. Centrino laptops with 4200RPM HDs).

I'll have to add some pictures later and some screenshots.  For now, I am beyond ecstatic that, finally, our entire team will be able to really be much, much more productive.  I can't say enough about our once CEO and now VP who really went the distance to make sure that we got some quality hardware.

So this morning, I was contemplating signing up for Amazon Prime since the holiday shopping season is a mere three months away and because I just moved to a new house that's kind of out in the middle of nowhere.

In doing some research about the general satisfaction about the service, I came across an amazing find on the BusinessWeek website, of all places.

The article/post itself isn't so interesting or amazing in any sense, rather, it's the comments left by the readers that are amazing and utterly baffling.

Who would have thought that the readers of BusinessWeek are such giant retards who have no concept of how the Interwebs work?  Nay, who would have thought that they were so dense as to not have any concept of how customer service works?

As evidence, I present some of the comments to the article:

I had no idea that it would cost me 79 dollars to join the shipping club and would not have joined if I did. I don't order that much and don't care if it took longer.

I would like to cancel my membership and get a refund for that amount. The one purchase I made took longer then two day's anyway. It was not even paid for or shipped till 8 o2. I have not even receive any imformation about the club yet.

Than You
Donald TenEyck

Hey Donald, this is BusinessWeek, not the Amazon customer service page...get a clue!  I'm pretty sure that Jeff Bezos is not going to call you and apologize.

I have just received a charge on my Visa bill
for $79.00. I did not authorize this and will not
pay it. Please cancel "MY MEMBERSHIP" and I will expect confirmation from you immediately. I notice that I am not the only one that has unknowingly been charged. What a rip off. Please credit my account now. And then lose my email
address
Bonnie Smuffer

Is it really possible for people to be this dense and stupid and yet have access to the Internet?

And it goes on and on...the stupidity really reaches critical mass in this posting.  Of course, it's fully possible that it's just comment spam, but check out these two postings by "Jaques Laporte":

Hi AMAZON.COM

I have just received a charge on my Amex bill for $79.00.

>PRIME SHIPPING CLUB.
>Free Standard Shipping for eligible items shipped to P.O. boxes in the continental United States (excluding Alaska, Hawaii, and U.S. >territories, possessions and protectorates) and APO/FPO addresses with U.S. zip codes.

Note that I do not live in the continental USA.

I did not authorize this and will not pay it. AMEX will be notified.

Please cancel my so-called membership and refund me.
I don't want to spoil my relation with Amazon, but until total refund, YOU ARE NOT AUTHORIZED to bill directly my credit cards.
Take notice please that I currently have no payment methods in your system.

Best regards.
Jacques Laporte.

Posted by: Jacques Laporte at January 3, 2007 06:56 AM

And then:

I must confess that the refund was fast (2 days).
All's well that ends well.

Posted by: J. Laporte at January 5, 2007 12:38 PM

Amazing to think that there are such a large quantity of people with this level of stupidity...

I originally came across a title Framework Design Guidelines: Conventions, Idioms, and Patterns for Reusable .NET Libraries after perusing the documentation on the Subtext site.

For the most part, I had been following the guidelines outlined by Scott Bellware in his handy dandy style guide, but this text - FDG - takes it to another level and formalizes it in a way that it must be accepted by development teams since it was born from the source itself: the .NET Framework development teams.

I've reviewed it on Amazon, but here is the transcripted text:

I don't personally think that all developers will find this book useful. In fact, I have a feeling that some may find it highly useless and disruptive as it is abstract in a sense (one must apply the lessons to each library and scenario independently, taking into consideration many different aspects of usability and readability) and it does require some "retraining" of bad practices which have been long since ingrained due to years of usage.

But whether this book deserves a five star rating or a one star rating - whether this book is for you - can be answered by asking yourself the following question: are you obsessed with quality? Quality in the sense of creating a library that is:

- Easily reused by others, even first timers encountering the library or even first timers to .Net
- Well thought out with well designed classes
- Consistent within itself and consistent with the base libraries from Microsoft

The importance of the little things like naming classes, properties, methods, using one type of construct over another, using one type of accessor over another, etc. cannot be stressed enough in the overall picture of creating a library to a higher standard of quality, usability, and extensibility.

As Confucius is to have said:

"If names be not correct, language is not in accordance with the truth of things. If language be not in accordance with the truth of things, affairs cannot be carried on to success.

"When affairs cannot be carried on to success, proprieties and music do not flourish. When proprieties and music do not flourish, punishments will not be properly awarded. When punishments are not properly awarded, the people do not know how to move hand or foot.

"Therefore a superior man considers it necessary that the names he uses may be spoken appropriately, and also that what he speaks may be carried out appropriately. What the superior man requires is just that in his words there may be nothing incorrect."

As I wrote in an e-mail to my team, I think that digesting this book will lead to: higher quality public facing APIs for our customer development teams seeking to extend the functionality, increased readability and more consistency internally in our teams, increased usability and decreased maintenance costs for the support teams as well as new developers on our team, and of course, increased skill, knowledge, and competency as developers of each of the team members.

The title of this book is perhaps a bit misleading.  In reality, this book is applicable for anyone doing .Net development since it will lead to better quality code construction irregardless of whether you happen to be working on a "framework".  What I also like about the book is that the authors, architects, and various developers who worked on the .NET Framework admit error and inconsistency in some design and shows that this book is truly a work of the men in the trenches and intended for those of us who work on the front line of software development.

While the book does not delve into architecture or design, I think it still has value in enhancing the skill and mastery of any developer that takes the time to read it.  Definitely pick up this book if you are serious about becoming a better developer in the sense of being a more refined craftsman.

If you are proxying Subversion through Apache, chances are you are probably using a non-default port since Apache won't start if you configure it use port 80 and 443 for SSL if you have IIS installed.  IIS uses socket pooling which binds port 80 and 443 on all IPs -- even ones not use by IIS -- to IIS.

To disable this behavior, you need the httpcfg.exe utility.  For Windows Server 2003, this can be found in the SP1 32-bit Support Tools download.  For Windows XP, the utility is available as part of the SP2 Support Tools download.

You can find a good overview of how to use this tool at neowin.net.

Some tips:

• I didn't have luck running net stop http /y alone; I had to stop IIS first by running net stop iisadmin.
• Assuming you have two or more IPs, the key is that you are actually telling IIS which IPs are okay to bind to.  If you are proxying Apache over IIS, you are likely (or should) use SSL.  This means that you have to make sure that you explicitly force IIS to bind to 80 and 443 for a specific IP and leave the other IP available for Apache.

Okay, so this isn't strictly a development tool, but Gantt Project has a pretty nifty, free, project management application.

With GanttProject you can break down your project into a tree of tasks and assign human resources that have to work on each task. You can also establish dependencies between tasks, like "this task can't start until this one is finished". GanttProject renders your project using two charts: Gantt chart for tasks and resource load chart for resources. You may print your charts, generate PDF and HTML reports, exchange data with Microsoft(R) Project(TM) and spreadsheet applications.

The site also mentions a good point with regards to Project:

• Good (and growing!) set of basic features. This set is enough for most people (remember that 80% of MSProject customers use 20% of it's numerous features)
• Easy learning. You don't need thick manuals to start working with GanttProject. If you are familiar with the notion of tasks, assignments and dependencies, you'll become an expert in GanttProject in a couple of hours.

Check it out if you're in the market for a free, simple, task based project management.

Frequently, when working with Office, SharePoint, and SharePoint web services, it is necessary to convert between the "normalized" (hex escaped string) version of a field name.

To that end, I found a useful JavaScript tool for normalizing strings into SharePoint's "static name" format.

In .Net, we can simplify this using Regex and Uri.

    private static readonly Regex specialCharactersPattern
        = new Regex("[\\[*($%&)<>!?\\/\"{}\\s+-='@~`#\\\\:;^\\]]", 
            RegexOptions.Compiled);

    private static readonly Regex encodedCharactersPattern
        = new Regex("_x00(\\d{2})_", RegexOptions.Compiled);

    /// <summary>
    /// Normalizes the name of the SharePoint property name.
    /// </summary>
    /// <param name="key">The "human readable" key/property name.</param>
    /// <returns>
    /// The string with hex representation in place of special ASCII
    /// characters.
    /// </returns>
    private static string NormalizeSharePointPropertyName(string key) {
        return specialCharactersPattern.Replace(key, ReplaceSpecialCharacter);
    }

    /// <summary>
    /// Custom match evaluator to replace special characters within the input
    /// string.
    /// </summary>
    /// <param name="match">The pattern match.</param>
    /// <returns>The formatted version of the string.</returns>
    private static string ReplaceSpecialCharacter(Match match) {
        string replacement = string.Format("_x00{0}_",
            Uri.HexEscape(match.Value[0]).TrimStart('%'));

        return replacement;
    }

    /// <summary>
    /// Denormalizes the name of the SharePoint property.
    /// </summary>
    /// <param name="key">The normalized key/property name (static name).</param>
    /// <returns>
    /// The denormalized form of the input string ("human readable"
    /// with hex patterns replaced).
    /// </returns>
    private static string DenormalizeSharePointPropertyName(string key) {
        return encodedCharactersPattern.Replace(key, DecodeSpecialCharacter);
    }

    /// <summary>
    /// Custom match evaluator to replace the hex characters with special characters.
    /// </summary>
    /// <param name="match">The pattern match.</param>
    /// <returns>The ASCII format of the special character encoded in hex.</returns>
    private static string DecodeSpecialCharacter(Match match) {
        int start = 0;

        string replacement =
            Convert.ToString(
                Uri.HexUnescape(Convert.ToString(match.Value[0]), ref start)
            );

        return replacement;
    }

Download the sample console project to test it out.

SharePointNormalizationConsole.zip (4.35 KB)

This is probably the most sensible an informative bit of commentary on the current market conditions (DOW -387):

I love how 90% of farkers don't understand exactly what the crisis is right now.

It's not the fact that the housing bubble "burst". People aren't jumping out of skyscrapers because their house value went down by 5%.

The vast majority of the problem is that the credit market for certain types of bonds has tightened up, to the point that it's almost not even trading at this point. To those that are newbies, the bond market is roughly 10x the size of the stock market in terms of dollar value. It is huge. Bonds get traded back and forth every day, and billions upon billions of dollars worth.

What happened is that mortgage-backed securities are farked up. During the housing boom, lenders would give mortgages to people, then they would package them up and then sell a whole shiatload of mortgages to things like pension funds, hedge funds, mutual funds, etc. The lenders like this because they reduce their risk, and the funds like it because it's a reliable source of income, at least mortgage-backed securities are. Well, it turns out that the lenders were selling the funds investment grade mortgages, when in fact they were more like junk bonds; the people who got these mortgages not only faked their income, but in reality could only afford these mortgages under the best of conditions. Now that short-term interest rates have spiked up, many people have defaulted on these loans. More importantly however, the price of the mortgage-backed securities drop because their price is in part related to how reliable they are as an investment.

Now, many hedge funds invest in MBSs on margin, which really screws them up, because all of a sudden they owe a huge amount of money on worthless securities. This is why 2 Bearn Sterns hedge funds got screwed over and a 3rd one is in question. It's like owning stock in a gold mining company with a certain reported amount of gold, and then finding out that there really is no gold. The price will plummet, and if you bought that stock on margin, you will get a margin call.

The same thing happened with the French hedge fund that this article is talking about. What is worse, however, is that if the markets aren't trading, you can't tell how much the stock is worth, so the French stopped trading the funds until it can get better clarity as to how much their fund is worth.

The submitter's headline is misleading because the govt isn't injecting $12 billion, it's $12 billion more than they usually inject. They are always buying and selling bonds to create liquidity. This is what they mean by the US or Euro governments injecting funds into the bond market. They are going around buying bonds to create an artifical market because regular traders aren't buying them anymore. They are buying these bonds to create liquidity, so that traders will have confidence they can buy and sell bonds again, and once the market recovers they will turn around and start selling them back to replenish their reserves.

This is the real danger here. This MBS contagion has spread throughout the world because every one around the world has invested in US MBSs. We have no idea how bad this contagion has spread, but if this MBS problem takes down funds around the world, and the credit market really tanks and there is a flight to quality, making things like MBS fall even further, it could literally evaporated trillions dollars of peoples investments around the world.

From poster tstoneman.