Aug 1, 2010 Posted by John MacIntyre

What’s wrong with the noun/adjective/verb object oriented design strategy

The programming course I took way back in 1993 was basically a 1 year intro to C. And like any good student, as I learned the language, I also started learning about code reuse and experienced a delightful satisfaction every time I realized 2 different functions had similar code which could be moved into a new function. Eventually, I noticed a pattern, in that I would write a bit of functionality until it worked, then I would refactor it into a more elegant solution with as little repeated code as possible. My code evolved quite nicely. Then I learned C++, object oriented programming, and was introduced to the holy grail of object oriented design advice, which went something like this: Take your requirements and circle all the nouns, those are your classes. Then underline all the adjectives, those are your properties. Then highlight all your verbs, those are your methods This Noun / Adjective / Verb design strategy seemed like the most ingenious piece of programming wisdom ever spoken … but it’s led us down a misguided path. It’s the verb that’s misunderstood. The verb should be another class, not a method. It should be a process class. As a programming concept, a process is just as much a ‘thing’ as any real world object. The verb should be a class, which accepts the noun as an input to be processed. But there’s also another problem; Up until this little shortcut was articulated, code was structured based on the implemented code, with similar functionality refactored into its own reusable units, but once noun/adjective/verb idea became widespread, code was suddenly structured according to domain. For example, the domain focus was really evident in the way we structured our ‘is-a’ relationships, with inheritance being based more on the real world domain, than the implementation code. Inheritance should be based on most efficient code reuse, not the domain, because as anybody who has heard the square is not a rectangle* example can attest, sometimes the domain ‘is-a’ relationship just doesn’t work. * With regards to the square is not a rectangle example, please be aware the solution outlined does not resolve the problem, as described in Uncle Bobs comment. The 1996(?) magazine article, The Liskov Substitution Principle is available, which contains the example as originally described. I didn’t post this url, since it’s not focused exclusively on the square / rectangle issue. Copyright © John MacIntyre 2010, All rights... read more

Jul 2, 2010 Posted by John MacIntyre

Visual Studio Bug – ‘if’ followed by a try / catch causes debugger stepping error

Yesterday I was debugging and stepped into a method. I wanted to get past my parameter validation checks and into the meat of the method, so I quickly, F10’d my way down the method, but I noticed a line of code was stepped on which should not have been touched. The code was a simple parameter validation like: 1 2 if (enumerableObj == null) throw new ArgumentNullException("enumerableObj");if (enumerableObj == null) throw new ArgumentNullException("enumerableObj"); with several similar parameter validation lines above it and a try/catch block containing the meat of the method below it. The odd thing was, I thought I saw the debugger step on the throw statement even though the enumerableObj should have had a value. I assumed I had somehow passed in a null value to the enumerableObj parameter and had nearly missed the problem in my haste. I had been moving quickly, so quickly in fact that I had stepped about 3 more lines into the method before I even stopped. To be honest at this point, I wasn’t even sure if I saw it step into the ‘if’ block, so I repositioned my debug cursor back to the ‘if’ condition, and stepped again. Sure enough, it stepped into the ‘if’ block. I assumed I passed in a null parameter, but when I evaluated enumerableObj, it was set, what’s more, evaluating the entire enumerableObj == null expression resulted in false, as expected. But why the heck was I being stepped into the ‘if’ block when the ‘if’ condition was false? I retried it again, just in case the enumerableObj had somehow been set as a result of a side effect somewhere, but even then, it still stepped into the ‘if’ block. So, I did the standard stuff; cleaned my solution, deleted my bin and obj directories, reopening the solution, restarted Visual Studio, & rebooted, all the while rebuilding and retesting the project with each change. Nothing seemed to work. I even cut & pasted my code into notepad, then cut & pasted from notepad back into Visual Studio to ensure there was no hidden characters in my files.* None of this worked, so I started commenting out code in the method, and eventually was able to isolate it to the above code failing if, and only if, it was followed by a try / catch block. Seriously! If the try / catch block was there, it would step onto the throw statement even though it should... read more

Apr 1, 2010 Posted by John MacIntyre

An Abstract Data Model

This is post 3 from a 7 part series entitled Technical Achievements in my Last Project. Overview Normally, when I build a new system, I design the new data model based on the requirements, and build my business objects and data access, based primarily on a that data model*. The remainder of the application is built on the components beneath it, so when you change something at the bottom, like the data model, changes ripple throughout the application. The data model serves as the foundation of my application. Now as far as this project goes, one of the important requirements was to deliver the new system incrementally, while leaving the older system to run in parallel until completely replaced. Parallel Data Models This presented a bit of a dilemma for me since the current database was … well … lacking, and I was planning to refactor it enough to make it a very unstable foundation for the old system. I wanted to refactor it for a number of reasons including; missing primary keys, no foreign keys, no constraints, data fields which were required but not there, data fields which were there but not used, data fields containing 2 or more pieces of information, and tables which should have been multiple tables. Not to mention the desire to achieve a consistent naming convention without the insane column names using characters like ‘/’ and ‘?’ … seriously. However the parallel systems requirement caused a bit of a dilemma. I mean, how do you manage parallel systems, one of which needs a stable foundation, and the other is so temperamental that you don’t want to touch it. My options as I saw them were something like: Scrap the data model refactoring. This really didn’t get much thought. Well it did, but the thought was, is this the best route for the client? And if so, should I offer to help them find my replacement or just leave? I definitely wasn’t up for replacing one unmaintainable piece of junk for another. New data model and re-factor the existing app. The existing application was a total nightmare built in classic Access spaghetti code fashion. Just touching that looked like going down a rabbit hole of certain doom. New application on the old data model and refactor the data model later. This would have caused a real disconnect between the data model and the application. I’m not sure if the data model and application ever... read more

Mar 29, 2010 Posted by John MacIntyre

Hey #region haters; Why all the fuss?

I hear a lot of programmers saying #regions are a code smell. From programmers I don’t know to celebrity programmers, while the development community appears to be passionately split.* The haters definitely have a point about it being used to hide ugly code, but when I open a class and see this, it just looks elegant to me. Now none of these regions are hiding thousands of lines of ugly code, actually, most of these regions contain only 3 properties and/or methods and the last curly brace is on line 299. So the whole thing with 17 properties and methods including comments and whitespace is only 300 LOC. … really, how much of a mess could I possibly be hiding? To me, the only question is whether I should have this functionality in the ContainerPageBase or the MasterPageBase**. You may also notice the regions I have are not of the Fields / Constructors / Events / Properties / Methods variety. It has taken some time for me to accept that all data members (aka fields) do not need to be at the top of the class as I was classically trained to do and that perhaps grouping them by functionality is a better idea. This philosophy only makes regions that much more valuable. … is anybody still here? …. have I converted anyone? 😉 * These posts are fairly old, but in my experience in the developer community; the consensus hasn’t changed. ** The Database Connection & Current User regions may have some scratching their heads. There are valid reasons for them, however the Data Connection region will never be included at this level again. More on that in a future post. Copyright © John MacIntyre 2010, All rights... read more

Mar 25, 2010 Posted by John MacIntyre

Large Application Estimation in 2 Weeks

This is post 2 from a 7 part series entitled Technical Achievements in my Last Project. My role in this project started out by being asked to assess the existing project, provide insight into options to move it forward, with one of those options being a rewrite*. An estimation was needed for the rewrite option, so I was given 2 weeks to do it. This post explains how I was able to pull off this massive estimation undertaking in a mere 2 weeks. Ideally, the project documentation from the existing system could be used to give an excellent estimate, but this is a blog post, not a fairly tale. Or a thorough specification could have derived from an in depth analysis of the existing application, which business could have adjusted as needed, and used to conclude a reasonable estimate. But this is the real world, and this is a real business; and I was given a real (short) deadline. Now I should also mention this wasn’t a 20 KLOC project, it was a fairly complex piece of software with over 500 KLOC** and almost 1800 database objects along with satellite applications. Everybody understood how this short timeframe severely limited the accuracy of anything I would be able to provide, but I was determined do the best job possible. So my next goal was to figure out how to do a somewhat accurate estimate, provided the constraints, where I wouldn’t be setting myself up for a lynching at the end of it. I explored many different ways to get a rough idea about the entire projects scope. This is what I finally settled on: Dumped all Microsoft Access Objects First I modified an Access VBA script I found for exporting objects to text files and exported everything. Dumped all database DDL I wrote a little command line utility to loop through a SQL Server database, pull the DDL for each object using the sp_helptext stored procedure, and write it out to text files. Created an analysis database Created an analysis database primarily comprised of three tables; one for all the entities the application is comprised of, a second for linking which entity called which, and the third for linking menu items to all dependent forms. Collected the names of all objects into the database I wrote another little command line utility to read each code file dumped out in steps 1 & 2, and add the objects name and a... read more

Mar 22, 2010 Posted by John MacIntyre

Technical Achievements in my Last Project

I’ve wanted to write this series for a long time, but hadn’t gotten around to it. Now, however, with my contract ending soon, I feel if I don’t write some of this down, I will never find the time, and it will be lost forever, which would be disappointing since I feel there are some really interesting things I did on this project which could benefit others. This isn’t about the kludges needed to fix Microsoft’s dysfunctional webforms architecture to work the way I need it to. It’s not about how to fire a server side event from a client side created button or how to write JavaScript for an ASCX used multiple times on the same page, when you don’t know what the rendered ID will be, and it’s not about overcoming resistance created by bizarre vendor API paradigms or outright bugs. It’s about overcoming the big requirements challenges placed before me. The project basically revolved around a significantly large and complex Microsoft Access application which had many issues. It was determined the best course of action was to rebuild it as an ASP.NET web application. However two important constraints placed upon me were; a) development could not be done in parallel, switching everybody over all at once upon completion, b) the new web application must be run from within the existing MS Access application and interact seamlessly until the MS Access app is completely replaced. The first constraint wasn’t a big deal until you consider the fact that the existing database was a total mess, needing refactoring, and the Access app was a spaghetti code nightmare where changes could potentially drag into eternity. It was wisely decided very early on that we would not do anything to upset the stability of the existing application. The series will cover some of the more interesting things done on this project and will be over 7 parts: Introduction and Overview Introduction to the series, brief run down of the general requirements and intention of the project. Large Application Estimation in 2 Weeks How I assessed the condition of a very large and complex MS Access application with 540 KLOC and almost 1,800 database objects, and how I was able to provide a very rough estimate to its reconstruction with a 2 week deadline. I expect to be able to piece together how I did this from memory and rough notes I have, but if I’m unable to come up with... read more

Mar 17, 2010 Posted by John MacIntyre

7 Features I Wish C# Had

…I couldn’t come up with 10 things I hate about C#, so I’m going to settle for 7 features I’d like to see. There may be good reasons why we don’t have some of them, but here’s my list anyway…

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Jan 28, 2010 Posted by John MacIntyre

Workaround: Visual Studio Debugger will not step.

Often while I’m stepping through server side code, I’ll get the error message “Unable to step. The operation could not be completed. A retry should be performed.” Or the “Unable to step. The message filter indicated that the application is busy.” message. Once you’ve gotten either of these messages, neither F10 or F11 will work, you just keep getting the same message. Finding information on this problem has been elusive, but I finally found this blog post which confirms the problem I’ve always suspected, that it’s a race condition in the VS debugger which is triggered by pressing either F10 or F5 at the same time as a javascript event is triggered in IE. The blog post outlines 3 workarounds, none of which I care for, so I thought I’d share a little trick I’ve discovered which will usually allow you to get back on track and start debugging again. Here’s how I get the debugger back on track: Place a break point on the next line of code Press F5 When the break point is hit, F10 & F11 will work again Warning: There have been a few times when the debugger did not stop on my breakpoint, but for the most part, it stopped 99% of the time. I may have missed a distinction in those few... read more