Humorous Software Licence Agreement #2

See also: Humorous Software Licence Agreement #1

Please note: I do not know what kind of legal protection against liability this licence will actually afford you. Please confer with an actual lawyer before attempting to use this in any legal capacity.

Software Usage License Agreement
Copyright (C) [copyright holders]
All rights reserved.

 * WITH NO GUARANTEES OF ANY KIND
THIS SOFTWARE IS PROVIDED:
 * AS-IS
 * NOT AS IT IS'NT
 * WITH NO WARRANTY OF ANY KIND
 * WITH NO PROMISES OF ANY KIND
 * WITH NO ASSURANCES OF ANY KIND
 * WITH A YAHOO TOOLBAR ATTACHED IF YOU DOWNLOADED IT FROM CNET

THIS INCLUDES, BUT IS NOT LIMITED TO:
 * WARRANTIES OF MERCHANTABILITY
 * GUARANTEE OF FITNESS FOR A PARTICULAR PURPOSE
 * ASSURANCES THAT IT WORKS, OR EVER WORKED, OR MIGHT WORK ANYTIME IN THE FUTURE
 * ASSURANCES THAT IT WILL NOT CAUSE YOU PSYCHOLOGICAL TRAUMA OR MENTAL HARM
 * PROMISES THAT IT WILL NOT CAUSE YOU TOTAL FINANCIAL RUIN
 * PROMISES THAT IT WILL NOT CAUSE YOU BODILY HARM OR PERSONAL INJURY
 * PROMISES THAT IT WILL NOT CAUSE YOUR SERVERS TO IGNITE IN FLAME
 * ASSURANCES THAT IT WILL NOT END THE HUMAN RACE
 * ASSURANCES THAT IT WILL NOT ANNIHILATE SPACE-TIME, AND THEREFORE EXISTENCE ITSELF
 * ASSURANCES THAT THESE WORDS ACTUALLY EXIST AND ARE NOT, IN FACT, AN ILLUSION
 
THEREFORE ANY PARTY THAT CHOOSES TO USE THIS SOFTWARE DOES SO AT THEIR OWN RISK AND
THEREFORE ASSUMES ANY RISK THAT IS DIRECTLY RELATED TO, CAUSED BY, OR ASSOCIATED WITH THE POSSESSION, READING, UNDERSTANDING, PRINTING, BURNING, USE OF, OR INTERACTION WITH THIS SOFTWARE
THEREFORE IT IS OF THE OPINION OF THE COPYRIGHT HOLDER/AUTHOR THAT THE SOFTWARE SHOULD NOT USED, BY ANYONE, FOR ANY PURPOSE, BUT DO NOT FORBID IT, AND FURTHERMORE, GRANT IT

It is hereby granted, to you, the rights to view it, use it, copy it, modify it, publish it, distribute it, sub-license it, or sell it for any purpose you see fit, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the software.

UNDER NO CIRCUMSTANCES AND IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT, COURSE OF BUSINESS, LATE-NIGHT DRUNKEN PRANKS, OR ACT OF,
OR OTHERWISE, ARISING FROM, OUT OF, OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE

Want to read more? I wrote a Humorous Software Licence Agreement #1 post with a similar-themed software licence.

Install C# on Raspberry Pi 2 with Mono

Intro

We can run C# on the Raspberry Pi 2! This has made the raspberry pi very valuable in my eyes. You can use Visual Studio to compile a .exe and then RUN IT on The Pi using Mono.

What I liked about The Pi: Getting it working was dead simple. I just formatted an SD card in FAT 32, downloading and extracting a 500mb .zip file and copying the contents of the extracted folder onto the SD card. After you've accomplished that, go take a beer break, you deserved it *whew*.

I was able to just plug in the cables, put in the SD card and I running Linux on The Pi. I was using the HDMI and Ethernet ports, however. If you wish to use the tiny, headphone-jack-looking component video or a USB wireless adapter however, there will be additional steps.

Problems / Gotchas 

Winforms may not play nice with Mono when on the Raspberry pi. Specifically, the problem manifests when you attempt to use a TextBox on your form, but who uses those? This bug  is supposedly fixed in the latest releases, but I have yet to get it to work by just updating my mono. It is very likely that I have to REBUILD mono from the latest source on the pi, which can take several hours. I have not tested this. The bug tracker for this says it has to do with with the pi's 'hard floats', which is referring to hardware floating point calculations.



The hardware is not exactly what I would call stable. Sometimes it does not POST (the BIOS is a binary blob, so does a pi really have a POST?). Anyways, ensure your USB charger that plugs into the wall that can supply plenty of power. The websites say 700ma at a minimum. I find using a 700ma charger is not sufficient. I use a charger that can push 2A, and I dont see many problems.

How does this work? 

A project called Mono. The Mono team has implemented a Common Language Runtime (CLR) that runs in the Linux and Mac environments and is coded to the ECMA-335 Common Language Infrastructure (CLI) AND covers functions and classes in the .NET framework, going all the way to 4.0 with some 4.5! Its open source, of course, and also has a compiler that follows the ECMA-334 C# Language Specification to turn C# code into CLI intermediate code that can be ran in windows as well. Remember, the CLI is just a specification that any language could (theoretically) be compiled to CLI.

Installing Mono C# on Raspberry Pi

This step was pretty straight forward as well. The instructions below are if you installed the NOOBS package which uses Raspian. If you have a different flavor of Linux, the commands below might be different.

You should already have sudo installed on your raspb pi. Prefixing a command with sudo allows you to run processes under a higher privilege without having to log into root. Also if you didnt know, the default username/password to log in the first time is pi/raspberry. If you prefer, you can type 'startx' to bring up the xwindows GUI. The commands below need to be entered into a terminal, which can be brought up within the GUI.

Fist, you want to update your Raspian to the latest version. To do that, you have to have the raspberry pi hooked up the the internet. If you have an ethernet cable and the router uses DHCP, plugging in the ethernet will be sufficient. Then, at the console simply enter the below line into the console:

sudo apt-get update

That may take a few minutes to complete and might prompt you to hit Y/N regarding the size of the package.

sudo apt-get install mono-runtime

This will also will take a few minutes to complete and might prompt you to hit Y/N regarding the size of the package.

After you've accomplished that, go have another beer because that was hard work!




Mono can now be used to run .NET executables:

mono Test.exe

Or, if your program requires elevated rights:

sudo mono Test.exe

Mono also features a REPL (read eval print loop). To access it, type 'csharp'. You can use your favorite text editor to make .cs files and compile them. My recommendation is, of course, to use Microsoft's Visual Studio. You can build and compile an application with MSVS in windows, and just transfer the executable by SCP or thumb-drive to the raspberry pi, which is pretty slick. Hats off to the developer(s) of Mono.

Hindenbugs, Heisenbugs and other types of software bugs

Different Types of Software Bugs

    Sorry, I haven't gotten around to creating a new post in close to a month (yikes!). I have just been super busy at work and have been trying to complete about 3 out of several not-quite-finished personal projects that I will be releasing on GitHub and blogging about

Heisenbug--

    1) A software bug that disappears or alters its behavior by the action of attempting to debug it.

    Possible sources: The effect of debuggers on the run-time code or JIT can be one source. Another might arise because of process scheduling or threading and race conditions. Or both, as stepping through the code with a debugger will affect the timing of threads.

    Derivation: Werner Heisenberg and his Uncertainty Principle.

Mandelbug--

    1) A bug whose causes are so complex it defies repair, or makes its behavior appear chaotic or even non-deterministic. Other symptoms include core dumps that, when viewed in an editor, form complex but repeating patterns or designs of characters and symbols.

    Possible sources: Operating system environment or configuration, the presence or absence of file system objects, time or scheduling-dependent code. Also, a very complicated state machine esp. one with more than one variable that hold state information and where transitions may not exists for every possible permutation of one state to another.

    Derivation: Benoît Mandelbrot and his research in fractal geometry.

Schrödinbug--

    1) A bug that manifests itself in running software after a programmer notices that the code should never have worked in the first place.

    Possible sources: A combination of naughty coding practices such as coding by coincidence and something else that allows for unexpected behavior such as a the effect of custom configurations or compiler optimizations, code obfuscation, or the JIT or on code. Also, a dependency on some arcane piece of technology that no one truly understands or employment of a black-box system or library, or some ancient, dinosaur system with a highly specific configuration that is so fragile that no-one dares update it because said updates could likely or is known to break functionality and where even a reboot is considered hairy.

    Derivation: Named for Erwin Schrödinger and his thought experiment.

Bohrbug--

    1) In contrast to the Heisenbug, the Bohrbug, is a "good, solid bug", easy to hunt down, or easily predicted from the description, esp. when a bug is the result of a classical programming mistake, or 'a rookie move'.

    Possible sources: Failing to initialize a variable or class to anything other than null, failure to RTFM, misuse of pointers or general abuse of memory, not coding defensively, coding by coincidence or not truly understanding how (or why) your code works.

    Derivation: Named after the physicist Niels Bohr and his rather simple atomic model.

Hindenbug--

    1) A bug with catastrophic consequences, esp. one that actually causes the server to burst into bright, hot flames.

    Possible sources: Code that dynamically builds and executes SQL scripts, esp. scripts that make use of the DELETE FROM command, code that is self modifying or replicates, or code that controls large machines or a physical system such as pumps, belts, cooling systems, aggregate pulverizer, fans, or any sort of thing with large, rotating blades. Also, any software that controls, monitors, tests, or is in any way whatsoever, wired up to a tactical nuclear defense system. In fact, lets just include anything with 'nuclear' or 'pulverize' in the name.

    Derivation: Refers to the Hindenburg disaster. The Hindenburg Blimp was, in turn, named after Paul von Hindenburg, the then-president of Germany from 1925->1934.

    Kishor S. Trivedi has a great talk/slideshow about Software Faults, Failures and Their Mitigations. He posits that it is not realistic to write software that is 100% bug free, or have 100% up-time. He displays the downtime in terms of minutes per year (MPY?) of several reliable corporations to support his claims, and it is true that as far as I am aware,there have not been any software ever written that did not have some downtime, even NASA.

    However, Trivedi shares a quote by one E. W. Dijkstra: "Testing shows the presence, not the absence, of bugs". Aww, logic. Now that's something I can get behind. Indeed; It is impossible to provably show that any software (of sufficient complexity) is absolutely error-free.

    Following this, he suggests we should not strive for the virtually impossible task building fault-free software, but rather aim to build instead fault-tolerant software.

Software Faults -> Software Errors -> Software Failures

Software Faults lead to Software Errors that lead to Software Failures.
Trivedi defines faults, errors and failures:
      -Software Failure occurs when the delivered service no longer complies with the desired output.
      -Software Error is that part of the system state which is liable to lead to subsequent failure.
      -Software Fault is adjudged or hypothesized cause of an error.Faults are the cause of errors that may lead to failures



    So, how does one test their tactical nuclear defense system code? VERY carefully, and it probably wouldn't hurt to comment out the Launch() method as well.

The Feature Flags Pattern

I was listening to Episode 1101 of the podcast Dot Net Rocks. Jez Humble was talking about the concept of Feature Toggles or Feature Flags. Feature Switches? While the term has some opinionated definitions, the concept that I found most interesting was the idea of deploying software with the new features initially disabled, or switched off by some mechanism. After you think the feature is ready for production, switch on the feature. If there is an issue, you don't have to roll back the version or deploy another release, just switch the feature back off again and replace its .dll. Didn't get enough debug information? Switch the feature back on and let a few crash reports trickle in and then switch it back off. If you feature is particularly processor or network intensive, you can perform load testing by slowly releasing the features to select clients or only part of the population/userbase.

While I personally choose an SQL table for my approach to storing the toggle switches (internal business app), one could use the application's .config file. An application could pull the settings from a .config file on a networked drive as a way of controlling multiple application instances by making one changed to a centralized location. Below I show a minimalist implementation by creating a Dictionary from the <appSettings> in a App.config file.

Behold:

public static Dictionary<string, bool> GetFeatureFlags()
{
  return ConfigurationManager.AppSettings.AllKeys.ToDictionary(s => s, IsFlagSet);
}

public static bool IsFlagSet(string settingName)
{
  bool result = false;
  bool.TryParse(ConfigurationManager.AppSettings[settingName], out result);
  return result;
}

Of course with a dictionary you have to be careful that you don't try an access a column that does not exist with the indexer, so you might be better off using IsFlagSet(string), which will never throw. Although this is of limited use (AppSettings is already a NameValueCollecion), perhaps you can make use of this generic function I wrote that uses generics to convert AppSettings into a dictionary with the type of the value being the generic:

public static Dictionary<string, T> GetDictionary<T>()
{
 return ConfigurationManager.AppSettings.AllKeys.ToDictionary<string, string, T>(s => s, GetSetting<T>);
}

public static T GetSetting<T>(string settingName)
{
  try
  {
    T result = (T) Convert.ChangeType(
      ConfigurationManager.AppSettings[settingName],
      typeof (T)
    );
    if (result != null)
    {
      return result;
    }
  }
  catch { }

  return default(T);
}

Please note that swallowing an exception ("catch { }") is typically considered poor form. In this particular scenario, I am aware of the possible exceptions that can be thrown by this code and I want the code to return the default(T) in this scenario and never throw.

EditLabel UserControl

EditLabel is editable Label control, who's text can be modified at run-time by double-clicking on it. Under the hood, it contains a Label control and TextBox control. It works like a Label control until you double-click it with the mouse. When double-clicked it enters 'edit-mode' where a TextBox overlays the Label. The control will AutoSize to the characters you type in the TextBox, updating the Label's size at the same time. You can leave the control's edit mode by hitting either enter, the escape key, or letting the control lose focus. After editing, the control acts like a label again, with the updated text. You can check out the code for the EditLabel project here on my GitHub.

The EditLabel isn't too interesting by itself, but I wanted to blog about it for all the interesting attributes that I never knew about until I started getting into designing controls, and controlling how controls are displayed in the designer window in visual studio.

The first thing my EditLabel control needed was and event that the parent form could subscribe to know when the text changed. Creating the event simply isn't enough. If you want the event to show up in the Visual Studio's Form Designer when you click on events, you need to add the Browsable and EditorBrowsable attribute. This will make is show up in the designer. You can control the description that appears as well as what category it shows up under when viewing events/properties in the Categorize view as opposed to Alphabetical view by using the Description and Category attributes respectively:

[Category("Property Changed")]
[Description("Event raised when the value of the Text property is changed on Control.")]
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
public new event EventHandler TextChanged;

There is also the notion of default events. That is, the event for which a handler is added when you double click the control in the designer. For example, when you double click a TextBox, it automatically adds the TextChanged event, instead of, say, the KeyDown event. To make an event the default event, add the DefaultEvent attribute at the control's class-level declaration:

[DefaultEvent("TextChanged")]
public partial class EditLabel : UserControl
{
   ...

Another thing I wanted was the Text property. Like a Label or a TextBox control, I wanted a public Text property that could be edited at design time. However, every time I re-built the project, the text would get reset to the default. As it turns out, if you want modifications to properties to be persisted, it must be serialized to the MainForm.Designer.cs, or whatever the auto-generated Designer.cs file is. In order to tell the designer to serialize changes made at design time to Designer.cs file, you have to add the DesignerSerializationVisibility attribute above the property. Here is the attributes and declaration for the Text property:

[Category("Appearance")]
[Description("The text associated with the control.")]
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
public override string Text
{
   get { return ctrlLabel.Text; }
   set { ChangeText(value); }
}

You can view the full EditLabel.cs here, or view the entire EditLabel project here.

Graceful Console Exit

When writing console apps sometimes you want to delay the closing of the console window to give the user time to read the output. Often, if something went wrong, I would simply report the error to the standard output and immediately exit the application. However that did not work too well for my users; the exit message was not displayed long enough for them to read so they knew how to correct the issue. What I needed was something that give a user enough time to read the output, but not prevent the process from exiting if it was being ran as a scheduled/automated task. The solution I came up with was a countdown timer that would block execution from proceeding until it counted back from some number to zero.

Lets view the code, shall we:

public static void CountdownTimer(int Seconds = 5)
{
    Console.ResetColor();
    Console.WriteLine(Environment.NewLine);
    Console.Write("The application will now terminate...   ");

    if (Seconds < 1) return;
    if (Seconds > 9) Seconds = 9;

    for (int counter = Seconds * 10; counter > 0; counter--)
    {
        if (Console.KeyAvailable)
            return;

        if (counter % 10 == 0)
            Console.Write("\b{0}", (counter / 10));

        System.Threading.Thread.Sleep(100);
    }
}

I print each number as the timer counts down. Each time I print a new number, I place a backspace "\b" before it to erase the previous number. To avoid having to keep track how many character a digit prints to use the same number of backspaces, I just kept the function simple by limiting the number of seconds to a max of 9.
I check for Console.KeyAvailable to detect key strokes to skip the rest of the countdown and exit immediately. The reason I did 10 Sleeps of 100ms per second was to make the exit upon key press more responsive.

Validate all input parameters in one line/Check several objects for empty or null in a single method call.

Often my methods start with several guarding clauses. That is, conditional if statements that check for null or empty parameters and immediately return if they are. This is also known as defensive programming. Usually I am not concerned with this code; indeed I identify these blocks as validation code and overlook this code entirely. It was not until recently that I noticed this as an area that I was repeating myself and could be put in a reusable function.

Lets look at the code:

/// <summary>
/// Checks the parameters for empty, nulls, or invalid states.
/// </summary>
/// <returns>True if the params are null, empty, contains an array or object that is null or empty, contains a blank, whitespace, null or empty string, or contains DataTable that does not pass a call to IsValidDatatable().</returns>
public static bool ContainsNullOrEmpty(params object[] Items)
{
    if (Items == null || Items.Length < 1)
        return true;
    
    foreach (object item in Items)
    {
        if (item == null)
            return true;
        
        if (item is string)
        {
            if (string.IsNullOrWhiteSpace(item as String))
                return true;
        }
        else if (item is DataTable)
        {
            if (!IsValidDatatable(item as DataTable))
                return true;
        }
        
        if (item.GetType().IsArray)
        {
            bool isEmpty = true;
            foreach (object itm in (Array)item)
            {
                if (ContainsEmptyOrNulls(itm))
                    return true;
                
                isEmpty = false;
            }
            if (isEmpty)
                return true;
        }
    }

    return false;
}

My approach above uses the params keyword. By using params, I can pass in any number of parameters (including zero, although that doesn't help us in this context). By using an object instead of a generic type I can pass multiple different types in one method call. If I used generics, I would have to have one method call for each type that I wanted to validate.

The idea is to cram all of your common validation logic into this method, and call it everywhere to increase the readability of your business logic by not cluttering it up with validation logic. Notice how this function also checks for empty or white-space strings, as well as calling a custom IsValidDatatable(DataTable) function. If you have several functions that return an int of -1 or 0 upon failure, you might want to add another conditional to check if (item is int) and then if the value of the integer reflects an erroneous state.

Another cool feature it that if the item is an an array, or even an array of nested arrays, it will still check every item in those arrays. Notice how I get the item type, then check the Type.IsArray property boolean. If it is true, I cast the object as an System.Array, then call ContainsEmptyOrNulls() recursively in a foreach loop. We can return true right away on the first null condition met, but we must be careful not to return on a false condition and to instead let the false conditions fall through and continue on, in the case that there is a null later or in another array.

Enjoy!

EntityJustWorks - C# class/object/entity to SQL database/script/command mapper.

Note by author:

   Since writing this, I have expanded on this idea quite a bit. I have written a lightweight ORM class library that I call EntityJustWorks.
   The full project can be found on GitHub or CodePlex.


   EntityJustWorks not only goes from a class to DataTable (below), but also provides:

• Populate the public properties of a class from a DataTable

• DataTable to class as a C# code file (using CodeDOM)

• DataTable to class Assembly (using Reflection.Emit)

• C# class to a SQL 'CREATE TABLE' or 'INSERT INTO' script

• SQL 'SELECT' statement to a List<T> of populated classes, each one resembling a row

Security Warning:
This library generates dynamic SQL, and has functions that generate SQL and then immediately executes it. While it its true that all strings funnel through the function Helper.EscapeSingleQuotes, this can be defeated in various ways and only parameterized SQL should be considered SAFE. If you have no need for them, I recommend stripping semicolons ; and dashes --. Also there are some Unicode characters that can be interpreted as a single quote or may be converted to one when changing encodings. Additionally, there are Unicode characters that can crash .NET code, but mainly controls (think TextBox). You almost certainly should impose a white list:
string clean = new string(dirty.Where(c => "abcdefghijklmnopqrstuvwxyz0123456789.,\"_ !@".Contains(c)).ToArray());

PLEASE USE the SQLScript.StoredProcedure and DatabaseQuery.StoredProcedure classes to generate SQL for you, as the scripts it produces is parameterized. All of the functions can be altered to generate parameterized instead of sanitized scripts. Ever since people have started using this, I have been maintaining backwards compatibility. However, I may break this in the future, as I do not wish to teach one who is learning dangerous/bad habits. This project is a few years old, and its already showing its age. What is probably needed here is a total re-write, deprecating this version while keep it available for legacy users after slapping big warnings all over the place. This project was designed to generate the SQL scripts for standing up a database for a project, using only MY input as data. This project was never designed to process a USER'S input.! Even if the data isn't coming from an adversary, client/user/manually entered data is notoriously inconsistent. Please do not use this code on any input that did not come from you, without first implementing parameterization. Again, please see the SQLScript.StoredProcedure class for inspiration on how to do that.

    In this post, I bring the wagons 'round full circle and use what I have shown you in older posts to make a class that can create (or insert into) a table in an SQL database from a C# class object at run-time. The only prior knowledge needed would be the connection string. The name of the the table will be the name of the class Type, and the tables's columns are created from the class's public properties, with their names being the property names.

    If you want to take a data-first approach, you can generate the code to C# classes that mirrors a table in a relational database given a connection string and the table name, or use the new Emit class and generate a dynamic assembly at run-time that contains a class with public auto-properties matching the DataColumns that you can use to store DataRows in. Similarly, the name of class name will be the same name as the table, with each of the table's columns being represented by a public auto property on the class of the same name and type. An improvement here would be to create the class inside a dynamic assembly using System.Reflection.Emit. Anywho, I have been holding on to this code for too long I just want to get it out of the door.

    For those of you who just want the code:
      GitHub  (Download zip)
      BitBucket (Download)
      code.msdn.microsoft.com

    Going from a query to a DataTable is as simple as a call to SQLAdapter.Fill(). For populating the public properties of a class from a DataTable, see this post I made. To build a DataTable who's columns match the public properties of a class, check out this post here. Going from a DataTable to a class as a C# code file is covered in this previous post.

    Going from a DataTable to SQL CREATE TABLE or INSERT INTO scripts that can be passed to ExecuteNonQuery() to execute the command, see below.

    Here is the INSERT INTO code. This code takes advantage of some functions in the Helper class that converts a DataTable's ColumnNames and Row's Values as a List of String, which is then passed into a function that takes a list of string and formats it with a delimiter string and prefix and postfix strings so I can easily format the list to look like the COLUMNS and VALUES part of an SQL INSERT INTO statement. For example: INSERT INTO ([FullName], [Gender], [BirthDate]) VALUES ('John Doe', 'M', '10/3/1981''). If you want to view how the functions RowToColumnString(), RowToValueString(), and ListToDelimitedString() work, click here to view Helper.cs.

public static string InsertInto<T>(params T[] ClassObjects) where T : class
{
   DataTable table = Map.ClassToDatatable<T>(ClassObjects);
   return InsertInto(table);   // We don't need to check IsValidDatatable() because InsertInto does
}

public static string InsertInto(DataTable Table)
{
   if (!Helper.IsValidDatatable(Table))
      return string.Empty;

   StringBuilder result = new StringBuilder();
   foreach (DataRow row in Table.Rows)
   {
      if (row == null || row.Table.Columns.Count < 1 || row.ItemArray.Length < 1)
         return string.Empty;

      string columns = Helper.RowToColumnString(row);
      string values = Helper.RowToValueString(row);

      if (string.IsNullOrWhiteSpace(columns) || string.IsNullOrWhiteSpace(values))
         return string.Empty;

      result.AppendFormat("INSERT INTO [{0}] {1} VALUES {2}", Table.TableName, columns, values);
   }

   return result.ToString();
}

    Here is the CREATE TABLE CODE. A very important function here is the GetDataTypeString() member, which converts the Column.DataType to the SQL equivalent as a string, which is used to craft a CREATE TABLE script. I use static strings formatted to work with String.Format to replace the crucial bits in the CREATE TABLE command:

public static string CreateTable<T>(params T[] ClassObjects) where T : class
{
 DataTable table = Map.ClassToDatatable<T>(ClassObjects);
 return Script.CreateTable(table);
}

public static string CreateTable(DataTable Table)
{
   if (Helper.IsValidDatatable(Table, IgnoreRows: true))
      return string.Empty;

   StringBuilder result = new StringBuilder();
   result.AppendFormat("CREATE TABLE [{0}] ({1}", Table.TableName, Environment.NewLine);

   bool FirstTime = true;
   foreach (DataColumn column in Table.Columns.OfType<DataColumn>())
   {
      if (FirstTime) FirstTime = false;
      else
         result.Append(",");

      result.AppendFormat("[{0}] {1} {2}NULL{3}",
         column.ColumnName,
         GetDataTypeString(column.DataType),
         column.AllowDBNull ? "" : "NOT ",
         Environment.NewLine
      );
   }
   result.AppendFormat(") ON [PRIMARY]{0}GO", Environment.NewLine);

   return result.ToString();
}

private static string GetDataTypeString(Type DataType)
{
   switch (DataType.Name)
   {
      case "Boolean": return "[bit]";
      case "Char": return "[char]";
      case "SByte": return "[tinyint]";
      case "Int16": return "[smallint]";
      case "Int32": return "[int]";
      case "Int64": return "[bigint]";
      case "Byte": return "[tinyint] UNSIGNED";
      case "UInt16": return "[smallint] UNSIGNED";
      case "UInt32": return "[int] UNSIGNED";
      case "UInt64": return "[bigint] UNSIGNED";
      case "Single": return "[float]";
      case "Double": return "[double]";
      case "Decimal": return "[decimal]";
      case "DateTime": return "[datetime]";
      case "Guid": return "[uniqueidentifier]";
      case "Object": return "[variant]";
      case "String": return "[nvarchar](250)";
      default: return "[nvarchar](MAX)";
   }
}

...


    Here is definition of all the public members:

namespace EntityJustWorks.SQL
{
   public static class Convert
   {
      public static string SQLTableToCSharp(string ConnectionString, string TableName);
      public static bool ClassToSQLTable(string ConnectionString, params T[] ClassCollection);
   }
   
   public static class Code
   {
      public static string SQLTableToCSharp(string ConnectionString, string TableName);
      public static string DatatableToCSharp(DataTable Table);
   }

   public static class Script
   {
      public static string InsertInto<T>(params T[] ClassObjects);
      public static string InsertInto(DataTable Table);
      public static string CreateTable<T>(params T[] ClassObjects);
      public static string CreateTable(DataTable Table);
   }
   
   public static class Map
   {
      public static IList<T> DatatableToClass<T>(DataTable Table);
      public static DataTable ClassToDatatable<T>(params T[] ClassCollection);
      public static DataTable ClassToDatatable<T>();
   }

   public static class Query
   {
      public static IList<T> QueryToClass<T>(string ConnectionString, string FormatString_Query,
                                                            params object[] FormatString_Parameters);
      public static DataTable QueryToDataTable(string ConnectionString, string FormatString_Query,
                                                            params object[] FormatString_Parameters);
      public static T QueryToScalarType<T>(string ConnectionString, string FormatString_Query,
                                                            params object[] FormatString_Parameters);
      public static int ExecuteNonQuery(string ConnectionString, string FormatString_Command,
                                                            params object[] FormatString_Parameters);
   }
   
   public static class Helper
   {
      public static bool IsValidDatatable(DataTable Table, bool IgnoreRows = false);
      public static bool IsCollectionEmpty<T>(IEnumerable<T> Input);
      public static bool IsNullableType(Type Input);
   }
}

    Please feel free to comment, either on my GitHub or my blog, with criticisms or suggestions.

Humorous and unhelpful Exception Class hierarchy

This post covers some of the lesser-known exception classes that exist. It is okay if you have never heard of these exception classes before... in fact, if you haven’t, that is probably a very, very good thing...





WTFException
The exception that is thrown when the code has encountered a genuine ‘WTF’ moment. This is usually only reserved for areas of the code that should never be reached, or indicates a state/condition that is either invalid, unexpected, or simply illogical. It can also be thrown to indicate that the developer has no idea why something is not working, and is at his wits end, or optionally at the end of some code that the developer was absolutely certain would never work.

See Also: CodeUnreachableException, ThisShouldNeverHappenException, and SpaceTimeException.

class WTFException : Exception
{
    public WTFException()
        : base() { }
    
    public WTFException(string message, params object[] messageParams)
        : base(string.Format(message, messageParams)) { }
    
    public WTFException(string message, Exception innerException)
        : base(message, innerException) { }
}

SpaceTimeException
The exception that is thrown when there is a serious problem with the fabric of space/time. Typically, the error message property will be empty or missing, as the actual even that caused this exception to be thrown has not yet occurred in the same timeline that your applications exists in. No attempt should be made to retrieve the InnerException object, as a black hole could result that would be almost certain to annihilate your code base, or possibly all of humanity. The only thing we can be certain of, however, is that your boss will be very cross with you and you will most likely get fired.

class SpaceTimeException : Exception
{
    public SpaceTimeException()
        : base() { }

    public SpaceTimeException(string message, Exception innerException)
        : base(message, innerException) { }
}

ArgumentInvalidException
You argument is invalid. You are wrong, your reasoning makes no logical sense, and you probably failed debate class in school. Even if your argument has some semblance of being based in logic or reality, you cannot argue with the compiler, there is no point, so quit trying.

class ArgumentInvalidException : Exception
{
    public ArgumentInvalidException()
        : base() { }

    public ArgumentInvalidException(string message, Exception innerException)
        : base(message, innerException) { }   
}

CodeUnreachableExeception
This exception is thrown when the assembly executes a block of code that is unreachable. This exception should never get thrown, and is, by definition, impossible. Catching this exception is like catching a leprechaun, and should it ever happen, the CLR will ask you for three wishes.

class CodeUnreachableExeception : Exception
{
    public CodeUnreachableExeception()
        : base() { }

    public CodeUnreachableExeception(string message, Exception innerException)
        : base(message, innerException) { }
}

OutOfCoffeeExecption
This exception is thrown when a developer has ran out of coffee or sufficient motivation to complete the function or feature. The exception is thrown at the exact line that the developer got up for a coffee break and never returned.

class OutOfCoffeeExecption : Exception
{
    public OutOfCoffeeExecption()
        : base() { }

    public OutOfCoffeeExecption(string message, Exception innerException)
        : base(message, innerException) { }
}

UnknownException
This exception is not thrown because a parameter or method specified is unknown, but rather that the implementing developer did not have the knowledge to implement the feature or method you just called, and threw this exception instead as quick and dirty solution.

class UnknownException : Exception
{
    public UnknownException()
        : base() { }

    public UnknownException(string message, Exception innerException)
        : base(message, innerException) { }
}

ThisIsNotTheExceptionYouAreLookingForException
What? Oh this? Oh, this was not meant for you. Now move along...

class ThisIsNotTheExceptionYouAreLookingForException : Exception
{
    /* Move along... */
}

Word Frequency Dictionary & Sorted Occurrence Ranking Dictionary for Generic Item Quantification and other Statistical Analyses

Taking a little inspiration from DotNetPerl's MultiMap, I created a generic class that uses a Dictionary under the hood to create a keyed collection that tracks the re-occurrences or frequency matching or duplicate items of arbitrary type. For lack of a better name, I call it a FrequencyDicionary. Instead of Key/Value pairs, the FrequencyDictionary has the notion of a Item/Frequency pair, with the key being the Item. I strayed from Key/Value because I may ultimately end up calling the Item the Value.

I invented the FrequencyDictionary while writing a pisg-like IRC log file statistics generator program. It works well for word frequency analysis. After some pre-processing/cleaning of the text log file, I parse each line by spaces to get an array of words. I then use FrequencyDictionary.AddRange to add the words to my dictionary.

The FrequencyDictionary is essentially a normal Dictionary (with T being type String in this case), however when you attempt to add a key that already exists, it simply increments the Value integer. After processing the file, you essentially have a Dictionary where the Key is a word that was found in the source text, and the Value is the number of occurrences of that word in the source text.

Taking the idea even further, I created complementary Dictionary that essentially a sorted version of FrequencyDictionary with the Key/Values reversed. I call it a RankingDictionary because the Keys represent the number of occurrences of a word, with the Values being a List of words that occurred that many times in the source text. Its called a RankingDictionary because I was using it to produce a top 10 ranking of most popular words, most popular nicks, ect.

The FrequencyDictionary has a GetRankingDictionary() method in it to make the whole thing very easy to use. Typically I don't use the FrequencyDictionary too extensively, but rather as a means to get a RankingDictionary, which I base the majority of my IRC statistics logic on. The RankingDictionary also proved very useful for finding Naked Candidates and Hidden Pairs or Triples in my Sudoku solver application that I will be releasing on Windows, Windows Phone and will be blogging about shortly. Hell, I was even thinking about releasing the source code to my Sudoku App, since its so elegant and a great example of beautiful, readable code to a complex problem.

Anyways, the code for the Frequency and Ranking Dictionary is heavily commented with XML Documentation Comments, so I'm going to go ahead and let the code speak for itself. I will add usage examples later. In fact, I will probably release the pisg-like IRC Stats Prog source code since I don't think I'm going to go any farther with it.

Limitations: I ran into problems trying to parse large text files approaching 3-4 megabytes. Besides taking up a bunch of memory, the Dictionary begins to encounter many hash collisions once the size of the collection gets large enough. This completely kills performance, and eventually most the time is spent trying to resolve collisions, so it grinds to a near halt. You might notice the constructor public FrequencyDictionary(int Capacity), where you can specify a maximum capacity for the Dictionary. A good, safe ceiling is about 10,000. A better implementation of the GetHash() method might be in order, but is not a problem I have felt like solving yet.

/// <summary>
/// A keyed collection of Item/Frequency pairs, (keyed off Item).
/// If a duplicate Item is added to the Dictionary, the Frequency for that Item is incremented.
/// </summary>
public class FrequencyDictionary<ITM>
{
  // The underlying Dictionary
  private Dictionary<ITM, int> _dictionary;
  
  /// <summary>
  /// Initializes a new instance of the FrequencyDictionary that is empty.
  /// </summary>
  public FrequencyDictionary() { _dictionary = new Dictionary<ITM, int>(); }
  
  /// <summary>
  /// Initializes a new instance of the FrequencyDictionary that has a maximum Capacity limit.
  /// </summary>
  public FrequencyDictionary(int Capacity) { _dictionary = new Dictionary<ITM, int>(); }
  
  /// <summary>
  /// Gets a collection containing the Items in the FrequencyDictionary.
  /// </summary>
  public IEnumerable<ITM> ItemCollection { get { return this._dictionary.Keys; } }
  
  /// <summary>
  /// Gets a collection containing the Frequencies in the FrequencyDictionary.
  /// </summary>
  public IEnumerable<int> FrequencyCollection { get { return this._dictionary.Values;} }
  
  /// <summary>
  /// Adds the specified Item to the FrequencyDictionary.
  /// </summary>
  public void Add(ITM Item)
  {
    if  ( this._dictionary.ContainsKey(Item))   { this._dictionary[Item]++; }
    else    { this._dictionary.Add(Item,1); }
  }
  
  /// <summary>
  /// Adds the elements of the specified array to the FrequencyDictionary.
  /// </summary>
  public void AddRange(ITM[] Items)
  {
    foreach(ITM item in Items) { this.Add(item); }
  }
  
  /// <summary>
  /// Gets the Item that occurs most frequently.
  /// </summary>
  /// <returns>A KeyValuePair containing the Item (key) and how many times it has appeard (value).</returns>
  public KeyValuePair<ITM,int> GetMostFrequent()
  {
    int maxValue = this._dictionary.Values.Max();
    return this._dictionary.Where(kvp => kvp.Value == maxValue).FirstOrDefault();
  }
  
  /// <summary>
  /// Gets the number of Item/Frequency pairs contained in the FrequencyDictionary.
  /// </summary>
  public int Count { get { return this._dictionary.Count; } }
  
  /// <summary>
  /// Returns an enumerator that iterates through the FrequencyDictionary.
  /// </summary>
  public IEnumerator<KeyValuePair<ITM,int>> GetEnumerator()
  {
    return this._dictionary.GetEnumerator();
  }
  
  /// <summary>
  /// Gets the Frequency (occurrences) associated with the specified Item.
  /// </summary>
  public int this[ITM Item]
  {
    get { if (this._dictionary.ContainsKey(Item)) { return this._dictionary[Item]; } return 0; }
  }
  
  /// <summary>
  /// Creates a RankingDictionary from the current FrequencyDictionary.
  /// </summary>
  /// <returns>A RankingDictionary of Frequency/ItemCollection pairs ordered by Frequency.</returns>
  public RankingDictionary<ITM> GetRankingDictionary()
  {
    RankingDictionary<ITM> result = new RankingDictionary<ITM>();
    foreach(KeyValuePair<ITM,int> kvp in _dictionary)
    {
      result.Add(kvp.Value,kvp.Key);
    }
    return result;
  }
  
  /// <summary>
  /// Displays usage information for FrequencyDictionary 
  /// </summary>
  public override string ToString()
  {
    return "FrequencyDictionary<Item, Frequency> : Key=\"Item=\", Value=\"Frequency\"\".";
  }
}

And now the RankingDictionary:

/// <summary>
/// A keyed collection of Frequency/ItemCollection pairs that is ordered by Frequency (rank).
/// If an Item is added that has the same Frequency as another Item, that Item is added to the Item collection for that Frequency.
/// </summary>
public class RankingDictionary<ITM>
{
  // Underlying dictionary
  SortedDictionary<int,List<ITM>> _dictionary;
  
  /// <summary>
  /// Initializes a new instance of the FrequencyDictionary that is empty.
  /// </summary>
  public RankingDictionary() { _dictionary = new SortedDictionary<int,List<ITM>>(new FrequencyComparer()); }
  
  /// <summary>
  /// The Comparer used to compare Frequencies.
  /// </summary>
  public class FrequencyComparer : IComparer<int>
  {
    public int Compare(int one,int two) { if(one == two) return 0; else if(one > two) return -1; else return 1; }
  }
  
  /// <summary>
  /// Gets a collection containing the Frequencies in the RankingDictionary.
  /// </summary>
  public IEnumerable<int> FrequencyCollection { get { return this._dictionary.Keys; } }
  
  /// <summary>
  /// Gets a collection containing the ItemCollection in the RankingDictionary.
  /// </summary>
  public IEnumerable<List<ITM>> ItemCollections   { get { return this._dictionary.Values; } }
  
  /// <summary>
  /// Adds the specified Frequency and Item to the RankingDictionary.
  /// </summary>
  public void Add(int Frequency, ITM Item)
  {
    List<ITM> itemCollection = new List<ITM>();
    itemCollection.Add(Item);
    // If the specified Key is not found, a set operation creates a new element with the specified Key
    this._dictionary[Frequency] = itemCollection;
  }
  
  /// <summary>
  ///  Gets the number of Frequency/ItemCollection pairs contained in the RankingDictionary.
  /// </summary>
  public int Count { get { return this._dictionary.Count; } }
  
  /// <summary>
  /// Returns an enumerator that iterates through the RankingDictionary.
  /// </summary>
  public IEnumerator<KeyValuePair<int,List<ITM>>> GetEnumerator()
  {
    return this._dictionary.GetEnumerator();
  }
  
  /// <summary>
  /// Gets the ItemCollection associated with the specified Frequency.
  /// </summary>
  public List<ITM> this[int Frequency]
  {
    get
    {
      List<ITM> itemCollection;
      if (this._dictionary.TryGetValue(Frequency,out itemCollection)) return itemCollection;
      else return new List<ITM>();
    }
  }
  
  /// <summary>
  /// Displays usage information for RankingDictionary 
  /// </summary>
  public override string ToString()
  {
    return "RankingDictionary<Frequency, List<Item>> : Key=\"Frequency\", Value=\"List<Item>\".";
  }
}

Usage examples will be posted later.