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  • Guide to reduce TFS database growth using the Test Attachment Cleaner

    - by terje
    Recently there has been several reports on TFS databases growing too fast and growing too big.  Notable this has been observed when one has started to use more features of the Testing system.  Also, the TFS 2010 handles test results differently from TFS 2008, and this leads to more data stored in the TFS databases. As a consequence of this there has been released some tools to remove unneeded data in the database, and also some fixes to correct for bugs which has been found and corrected during this process.  Further some preventive practices and maintenance rules should be adopted. A lot of people have blogged about this, among these are: Anu’s very important blog post here describes both the problem and solutions to handle it.  She describes both the Test Attachment Cleaner tool, and also some QFE/CU releases to fix some underlying bugs which prevented the tool from being fully effective. Brian Harry’s blog post here describes the problem too This forum thread describes the problem with some solution hints. Ravi Shanker’s blog post here describes best practices on solving this (TBP) Grant Holidays blogpost here describes strategies to use the Test Attachment Cleaner both to detect space problems and how to rectify them.   The problem can be divided into the following areas: Publishing of test results from builds Publishing of manual test results and their attachments in particular Publishing of deployment binaries for use during a test run Bugs in SQL server preventing total cleanup of data (All the published data above is published into the TFS database as attachments.) The test results will include all data being collected during the run.  Some of this data can grow rather large, like IntelliTrace logs and video recordings.   Also the pushing of binaries which happen for automated test runs, including tests run during a build using code coverage which will include all the files in the deployment folder, contributes a lot to the size of the attached data.   In order to handle this systematically, I have set up a 3-stage process: Find out if you have a database space issue Set up your TFS server to minimize potential database issues If you have the “problem”, clean up the database and otherwise keep it clean   Analyze the data Are your database( s) growing ?  Are unused test results growing out of proportion ? To find out about this you need to query your TFS database for some of the information, and use the Test Attachment Cleaner (TAC) to obtain some  more detailed information. If you don’t have too many databases you can use the SQL Server reports from within the Management Studio to analyze the database and table sizes. Or, you can use a set of queries . I find queries often faster to use because I can tweak them the way I want them.  But be aware that these queries are non-documented and non-supported and may change when the product team wants to change them. If you have multiple Project Collections, find out which might have problems: (Disclaimer: The queries below work on TFS 2010. They will not work on Dev-11, since the table structure have been changed.  I will try to update them for Dev-11 when it is released.) Open a SQL Management Studio session onto the SQL Server where you have your TFS Databases. Use the query below to find the Project Collection databases and their sizes, in descending size order.  use master select DB_NAME(database_id) AS DBName, (size/128) SizeInMB FROM sys.master_files where type=0 and substring(db_name(database_id),1,4)='Tfs_' and DB_NAME(database_id)<>'Tfs_Configuration' order by size desc Doing this on one of our SQL servers gives the following results: It is pretty easy to see on which collection to start the work   Find out which tables are possibly too large Keep a special watch out for the Tfs_Attachment table. Use the script at the bottom of Grant’s blog to find the table sizes in descending size order. In our case we got this result: From Grant’s blog we learnt that the tbl_Content is in the Version Control category, so the major only big issue we have here is the tbl_AttachmentContent.   Find out which team projects have possibly too large attachments In order to use the TAC to find and eventually delete attachment data we need to find out which team projects have these attachments. The team project is a required parameter to the TAC. Use the following query to find this, replace the collection database name with whatever applies in your case:   use Tfs_DefaultCollection select p.projectname, sum(a.compressedlength)/1024/1024 as sizeInMB from dbo.tbl_Attachment as a inner join tbl_testrun as tr on a.testrunid=tr.testrunid inner join tbl_project as p on p.projectid=tr.projectid group by p.projectname order by sum(a.compressedlength) desc In our case we got this result (had to remove some names), out of more than 100 team projects accumulated over quite some years: As can be seen here it is pretty obvious the “Byggtjeneste – Projects” are the main team project to take care of, with the ones on lines 2-4 as the next ones.  Check which attachment types takes up the most space It can be nice to know which attachment types takes up the space, so run the following query: use Tfs_DefaultCollection select a.attachmenttype, sum(a.compressedlength)/1024/1024 as sizeInMB from dbo.tbl_Attachment as a inner join tbl_testrun as tr on a.testrunid=tr.testrunid inner join tbl_project as p on p.projectid=tr.projectid group by a.attachmenttype order by sum(a.compressedlength) desc We then got this result: From this it is pretty obvious that the problem here is the binary files, as also mentioned in Anu’s blog. Check which file types, by their extension, takes up the most space Run the following query use Tfs_DefaultCollection select SUBSTRING(filename,len(filename)-CHARINDEX('.',REVERSE(filename))+2,999)as Extension, sum(compressedlength)/1024 as SizeInKB from tbl_Attachment group by SUBSTRING(filename,len(filename)-CHARINDEX('.',REVERSE(filename))+2,999) order by sum(compressedlength) desc This gives a result like this:   Now you should have collected enough information to tell you what to do – if you got to do something, and some of the information you need in order to set up your TAC settings file, both for a cleanup and for scheduled maintenance later.    Get your TFS server and environment properly set up Even if you have got the problem or if have yet not got the problem, you should ensure the TFS server is set up so that the risk of getting into this problem is minimized.  To ensure this you should install the following set of updates and components. The assumption is that your TFS Server is at SP1 level. Install the QFE for KB2608743 – which also contains detailed instructions on its use, download from here. The QFE changes the default settings to not upload deployed binaries, which are used in automated test runs. Binaries will still be uploaded if: Code coverage is enabled in the test settings. You change the UploadDeploymentItem to true in the testsettings file. Be aware that this might be reset back to false by another user which haven't installed this QFE. The hotfix should be installed to The build servers (the build agents) The machine hosting the Test Controller Local development computers (Visual Studio) Local test computers (MTM) It is not required to install it to the TFS Server, test agents or the build controller – it has no effect on these programs. If you use the SQL Server 2008 R2 you should also install the CU 10 (or later).  This CU fixes a potential problem of hanging “ghost” files.  This seems to happen only in certain trigger situations, but to ensure it doesn’t bite you, it is better to make sure this CU is installed. There is no such CU for SQL Server 2008 pre-R2 Work around:  If you suspect hanging ghost files, they can be – with some mental effort, deduced from the ghost counters using the following SQL query: use master SELECT DB_NAME(database_id) as 'database',OBJECT_NAME(object_id) as 'objectname', index_type_desc,ghost_record_count,version_ghost_record_count,record_count,avg_record_size_in_bytes FROM sys.dm_db_index_physical_stats (DB_ID(N'<DatabaseName>'), OBJECT_ID(N'<TableName>'), NULL, NULL , 'DETAILED') The problem is a stalled ghost cleanup process.  Restarting the SQL server after having stopped all components that depends on it, like the TFS Server and SPS services – that is all applications that connect to the SQL server. Then restart the SQL server, and finally start up all dependent processes again.  (I would guess a complete server reboot would do the trick too.) After this the ghost cleanup process will run properly again. The fix will come in the next CU cycle for SQL Server R2 SP1.  The R2 pre-SP1 and R2 SP1 have separate maintenance cycles, and are maintained individually. Each have its own set of CU’s. When it comes I will add the link here to that CU. The "hanging ghost file” issue came up after one have run the TAC, and deleted enourmes amount of data.  The SQL Server can get into this hanging state (without the QFE) in certain cases due to this. And of course, install and set up the Test Attachment Cleaner command line power tool.  This should be done following some guidelines from Ravi Shanker: “When you run TAC, ensure that you are deleting small chunks of data at regular intervals (say run TAC every night at 3AM to delete data that is between age 730 to 731 days) – this will ensure that small amounts of data are being deleted and SQL ghosted record cleanup can catch up with the number of deletes performed. “ This rule minimizes the risk of the ghosted hang problem to occur, and further makes it easier for the SQL server ghosting process to work smoothly. “Run DBCC SHRINKDB post the ghosted records are cleaned up to physically reclaim the space on the file system” This is the last step in a 3 step process of removing SQL server data. First they are logically deleted. Then they are cleaned out by the ghosting process, and finally removed using the shrinkdb command. Cleaning out the attachments The TAC is run from the command line using a set of parameters and controlled by a settingsfile.  The parameters point out a server uri including the team project collection and also point at a specific team project. So in order to run this for multiple team projects regularly one has to set up a script to run the TAC multiple times, once for each team project.  When you install the TAC there is a very useful readme file in the same directory. When the deployment binaries are published to the TFS server, ALL items are published up from the deployment folder. That often means much more files than you would assume are necessary. This is a brute force technique. It works, but you need to take care when cleaning up. Grant has shown how their settings file looks in his blog post, removing all attachments older than 180 days , as long as there are no active workitems connected to them. This setting can be useful to clean out all items, both in a clean-up once operation, and in a general There are two scenarios we need to consider: Cleaning up an existing overgrown database Maintaining a server to avoid an overgrown database using scheduled TAC   1. Cleaning up a database which has grown too big due to these attachments. This job is a “Once” job.  We do this once and then move on to make sure it won’t happen again, by taking the actions in 2) below.  In this scenario you should only consider the large files. Your goal should be to simply reduce the size, and don’t bother about  the smaller stuff. That can be left a scheduled TAC cleanup ( 2 below). Here you can use a very general settings file, and just remove the large attachments, or you can choose to remove any old items.  Grant’s settings file is an example of the last one.  A settings file to remove only large attachments could look like this: <!-- Scenario : Remove large files --> <DeletionCriteria> <TestRun /> <Attachment> <SizeInMB GreaterThan="10" /> </Attachment> </DeletionCriteria> Or like this: If you want only to remove dll’s and pdb’s about that size, add an Extensions-section.  Without that section, all extensions will be deleted. <!-- Scenario : Remove large files of type dll's and pdb's --> <DeletionCriteria> <TestRun /> <Attachment> <SizeInMB GreaterThan="10" /> <Extensions> <Include value="dll" /> <Include value="pdb" /> </Extensions> </Attachment> </DeletionCriteria> Before you start up your scheduled maintenance, you should clear out all older items. 2. Scheduled maintenance using the TAC If you run a schedule every night, and remove old items, and also remove them in small batches.  It is important to run this often, like every night, in order to keep the number of deleted items low. That way the SQL ghost process works better. One approach could be to delete all items older than some number of days, let’s say 180 days. This could be combined with restricting it to keep attachments with active or resolved bugs.  Doing this every night ensures that only small amounts of data is deleted. <!-- Scenario : Remove old items except if they have active or resolved bugs --> <DeletionCriteria> <TestRun> <AgeInDays OlderThan="180" /> </TestRun> <Attachment /> <LinkedBugs> <Exclude state="Active" /> <Exclude state="Resolved"/> </LinkedBugs> </DeletionCriteria> In my experience there are projects which are left with active or resolved workitems, akthough no further work is done.  It can be wise to have a cleanup process with no restrictions on linked bugs at all. Note that you then have to remove the whole LinkedBugs section. A approach which could work better here is to do a two step approach, use the schedule above to with no LinkedBugs as a sweeper cleaning task taking away all data older than you could care about.  Then have another scheduled TAC task to take out more specifically attachments that you are not likely to use. This task could be much more specific, and based on your analysis clean out what you know is troublesome data. <!-- Scenario : Remove specific files early --> <DeletionCriteria> <TestRun > <AgeInDays OlderThan="30" /> </TestRun> <Attachment> <SizeInMB GreaterThan="10" /> <Extensions> <Include value="iTrace"/> <Include value="dll"/> <Include value="pdb"/> <Include value="wmv"/> </Extensions> </Attachment> <LinkedBugs> <Exclude state="Active" /> <Exclude state="Resolved" /> </LinkedBugs> </DeletionCriteria> The readme document for the TAC says that it recognizes “internal” extensions, but it does recognize any extension. To run the tool do the following command: tcmpt attachmentcleanup /collection:your_tfs_collection_url /teamproject:your_team_project /settingsfile:path_to_settingsfile /outputfile:%temp%/teamproject.tcmpt.log /mode:delete   Shrinking the database You could run a shrink database command after the TAC has run in cases where there are a lot of data being deleted.  In this case you SHOULD do it, to free up all that space.  But, after the shrink operation you should do a rebuild indexes, since the shrink operation will leave the database in a very fragmented state, which will reduce performance. Note that you need to rebuild indexes, reorganizing is not enough. For smaller amounts of data you should NOT shrink the database, since the data will be reused by the SQL server when it need to add more records.  In fact, it is regarded as a bad practice to shrink the database regularly.  So on a daily maintenance schedule you should NOT shrink the database. To shrink the database you do a DBCC SHRINKDATABASE command, and then follow up with a DBCC INDEXDEFRAG afterwards.  I find the easiest way to do this is to create a SQL Maintenance plan including the Shrink Database Task and the Rebuild Index Task and just execute it when you need to do this.

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  • The Art of Productivity

    - by dwahlin
    Getting things done has always been a challenge regardless of gender, age, race, skill, or job position. No matter how hard some people try, they end up procrastinating tasks until the last minute. Some people simply focus better when they know they’re out of time and can’t procrastinate any longer. How many times have you put off working on a term paper in school until the very last minute? With only a few hours left your mental energy and focus seem to kick in to high gear especially as you realize that you either get the paper done now or risk failing. It’s amazing how a little pressure can turn into a motivator and allow our minds to focus on a given task. Some people seem to specialize in procrastinating just about everything they do while others tend to be the “doers” who get a lot done and ultimately rise up the ladder at work. What’s the difference between these types of people? Is it pure laziness or are other factors at play? I think that some people are certainly more motivated than others, but I also think a lot of it is based on the process that “doers” tend to follow - whether knowingly or unknowingly. While I’ve certainly fought battles with procrastination, I’ve always had a knack for being able to get a lot done in a relatively short amount of time. I think a lot of my “get it done” attitude goes back to the the strong work ethic my parents instilled in me at a young age. I remember my dad saying, “You need to learn to work hard!” when I was around 5 years old. I remember that moment specifically because I was on a tractor with him the first time I heard it while he was trying to move some large rocks into a pile. The tractor was big but so were the rocks and my dad had to balance the tractor perfectly so that it didn’t tip forward too far. It was challenging work and somewhat tedious but my dad finished the task and taught me a few important lessons along the way including persistence, the importance of having a skill, and getting the job done right without skimping along the way. In this post I’m going to list a few of the techniques and processes I follow that I hope may be beneficial to others. I blogged about the general concept back in 2009 but thought I’d share some updated information and lessons learned since then. Most of the ideas that follow came from learning and refining my daily work process over the years. However, since most of the ideas are common sense (at least in my opinion), I suspect they can be found in other productivity processes that are out there. Let’s start off with one of the most important yet simple tips: Start Each Day with a List. Start Each Day with a List What are you planning to get done today? Do you keep track of everything in your head or rely on your calendar? While most of us think that we’re pretty good at managing “to do” lists strictly in our head you might be surprised at how affective writing out lists can be. By writing out tasks you’re forced to focus on the most important tasks to accomplish that day, commit yourself to those tasks, and have an easy way to track what was supposed to get done and what actually got done. Start every morning by making a list of specific tasks that you want to accomplish throughout the day. I’ll even go so far as to fill in times when I’d like to work on tasks if I have a lot of meetings or other events tying up my calendar on a given day. I’m not a big fan of using paper since I type a lot faster than I write (plus I write like a 3rd grader according to my wife), so I use the Sticky Notes feature available in Windows. Here’s an example of yesterday’s sticky note: What do you add to your list? That’s the subject of the next tip. Focus on Small Tasks It’s no secret that focusing on small, manageable tasks is more effective than trying to focus on large and more vague tasks. When you make your list each morning only add tasks that you can accomplish within a given time period. For example, if I only have 30 minutes blocked out to work on an article I don’t list “Write Article”. If I do that I’ll end up wasting 30 minutes stressing about how I’m going to get the article done in 30 minutes and ultimately get nothing done. Instead, I’ll list something like “Write Introductory Paragraphs for Article”. The next day I may add, “Write first section of article” or something that’s small and manageable – something I’m confident that I can get done. You’ll find that once you’ve knocked out several smaller tasks it’s easy to continue completing others since you want to keep the momentum going. In addition to keeping my tasks focused and small, I also make a conscious effort to limit my list to 4 or 5 tasks initially. I’ve found that if I list more than 5 tasks I feel a bit overwhelmed which hurts my productivity. It’s easy to add additional tasks as you complete others and you get the added benefit of that confidence boost of knowing that you’re being productive and getting things done as you remove tasks and add others. Getting Started is the Hardest (Yet Easiest) Part I’ve always found that getting started is the hardest part and one of the biggest contributors to procrastination. Getting started working on tasks is a lot like getting a large rock pushed to the bottom of a hill. It’s difficult to get the rock rolling at first, but once you manage to get it rocking some it’s really easy to get it rolling on its way to the bottom. As an example, I’ve written 100s of articles for technical magazines over the years and have really struggled with the initial introductory paragraphs. Keep in mind that these are the paragraphs that don’t really add that much value (in my opinion anyway). They introduce the reader to the subject matter and nothing more. What a waste of time for me to sit there stressing about how to start the article. On more than one occasion I’ve spent more than an hour trying to come up with 2-3 paragraphs of text.  Talk about a productivity killer! Whether you’re struggling with a writing task, some code for a project, an email, or other tasks, jumping in without thinking too much is the best way to get started I’ve found. I’m not saying that you shouldn’t have an overall plan when jumping into a task, but on some occasions you’ll find that if you simply jump into the task and stop worrying about doing everything perfectly that things will flow more smoothly. For my introductory paragraph problem I give myself 5 minutes to write out some general concepts about what I know the article will cover and then spend another 10-15 minutes going back and refining that information. That way I actually have some ideas to work with rather than a blank sheet of paper. If I still find myself struggling I’ll write the rest of the article first and then circle back to the introductory paragraphs once I’m done. To sum this tip up: Jump into a task without thinking too hard about it. It’s better to to get the rock at the top of the hill rocking some than doing nothing at all. You can always go back and refine your work.   Learn a Productivity Technique and Stick to It There are a lot of different productivity programs and seminars out there being sold by companies. I’ve always laughed at how much money people spend on some of these motivational programs/seminars because I think that being productive isn’t that hard if you create a re-useable set of steps and processes to follow. That’s not to say that some of these programs/seminars aren’t worth the money of course because I know they’ve definitely benefited some people that have a hard time getting things done and staying focused. One of the best productivity techniques I’ve ever learned is called the “Pomodoro Technique” and it’s completely free. This technique is an extremely simple way to manage your time without having to remember a bunch of steps, color coding mechanisms, or other processes. The technique was originally developed by Francesco Cirillo in the 80s and can be implemented with a simple timer. In a nutshell here’s how the technique works: Pick a task to work on Set the timer to 25 minutes and work on the task Once the timer rings record your time Take a 5 minute break Repeat the process Here’s why the technique works well for me: It forces me to focus on a single task for 25 minutes. In the past I had no time goal in mind and just worked aimlessly on a task until I got interrupted or bored. 25 minutes is a small enough chunk of time for me to stay focused. Any distractions that may come up have to wait until after the timer goes off. If the distraction is really important then I stop the timer and record my time up to that point. When the timer is running I act as if I only have 25 minutes total for the task (like you’re down to the last 25 minutes before turning in your term paper….frantically working to get it done) which helps me stay focused and turns into a “beat the clock” type of game. It’s actually kind of fun if you treat it that way and really helps me focus on a the task at hand. I automatically know how much time I’m spending on a given task (more on this later) by using this technique. I know that I have 5 minutes after each pomodoro (the 25 minute sprint) to waste on anything I’d like including visiting a website, stepping away from the computer, etc. which also helps me stay focused when the 25 minute timer is counting down. I use this technique so much that I decided to build a program for Windows 8 called Pomodoro Focus (I plan to blog about how it was built in a later post). It’s a Windows Store application that allows people to track tasks, productive time spent on tasks, interruption time experienced while working on a given task, and the number of pomodoros completed. If a time estimate is given when the task is initially created, Pomodoro Focus will also show the task completion percentage. I like it because it allows me to track my tasks, time spent on tasks (very useful in the consulting world), and even how much time I wasted on tasks (pressing the pause button while working on a task starts the interruption timer). I recently added a new feature that charts productive and interruption time for tasks since I wanted to see how productive I was from week to week and month to month. A few screenshots from the Pomodoro Focus app are shown next, I had a lot of fun building it and use it myself to as I work on tasks.   There are certainly many other productivity techniques and processes out there (and a slew of books describing them), but the Pomodoro Technique has been the simplest and most effective technique I’ve ever come across for staying focused and getting things done.   Persistence is Key Getting things done is great but one of the biggest lessons I’ve learned in life is that persistence is key especially when you’re trying to get something done that at times seems insurmountable. Small tasks ultimately lead to larger tasks getting accomplished, however, it’s not all roses along the way as some of the smaller tasks may come with their own share of bumps and bruises that lead to discouragement about the end goal and whether or not it is worth achieving at all. I’ve been on several long-term projects over my career as a software developer (I have one personal project going right now that fits well here) and found that repeating, “Persistence is the key!” over and over to myself really helps. Not every project turns out to be successful, but if you don’t show persistence through the hard times you’ll never know if you succeeded or not. Likewise, if you don’t persistently stick to the process of creating a daily list, follow a productivity process, etc. then the odds of consistently staying productive aren’t good.   Track Your Time How much time do you actually spend working on various tasks? If you don’t currently track time spent answering emails, on phone calls, and working on various tasks then you might be surprised to find out that a task that you thought was going to take you 30 minutes ultimately ended up taking 2 hours. If you don’t track the time you spend working on tasks how can you expect to learn from your mistakes, optimize your time better, and become more productive? That’s another reason why I like the Pomodoro Technique – it makes it easy to stay focused on tasks while also tracking how much time I’m working on a given task.   Eliminate Distractions I blogged about this final tip several years ago but wanted to bring it up again. If you want to be productive (and ultimately successful at whatever you’re doing) then you can’t waste a lot of time playing games or on Twitter, Facebook, or other time sucking websites. If you see an article you’re interested in that has no relation at all to the tasks you’re trying to accomplish then bookmark it and read it when you have some spare time (such as during a pomodoro break). Fighting the temptation to check your friends’ status updates on Facebook? Resist the urge and realize how much those types of activities are hurting your productivity and taking away from your focus. I’ll admit that eliminating distractions is still tough for me personally and something I have to constantly battle. But, I’ve made a conscious decision to cut back on my visits and updates to Facebook, Twitter, Google+ and other sites. Sure, my Klout score has suffered as a result lately, but does anyone actually care about those types of scores aside from your online “friends” (few of whom you’ve actually met in person)? :-) Ultimately it comes down to self-discipline and how badly you want to be productive and successful in your career, life goals, hobbies, or whatever you’re working on. Rather than having your homepage take you to a time wasting news site, game site, social site, picture site, or others, how about adding something like the following as your homepage? Every time your browser opens you’ll see a personal message which helps keep you on the right track. You can download my ubber-sophisticated homepage here if interested. Summary Is there a single set of steps that if followed can ultimately lead to productivity? I don’t think so since one size has never fit all. Every person is different, works in their own unique way, and has their own set of motivators, distractions, and more. While I certainly don’t consider myself to be an expert on the subject of productivity, I do think that if you learn what steps work best for you and gradually refine them over time that you can come up with a personal productivity process that can serve you well. Productivity is definitely an “art” that anyone can learn with a little practice and persistence. You’ve seen some of the steps that I personally like to follow and I hope you find some of them useful in boosting your productivity. If you have others you use please leave a comment. I’m always looking for ways to improve.

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  • Abstracting functionality

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/22/abstracting-functionality.aspxWhat is more important than data? Functionality. Yes, I strongly believe we should switch to a functionality over data mindset in programming. Or actually switch back to it. Focus on functionality Functionality once was at the core of software development. Back when algorithms were the first thing you heard about in CS classes. Sure, data structures, too, were important - but always from the point of view of algorithms. (Niklaus Wirth gave one of his books the title “Algorithms + Data Structures” instead of “Data Structures + Algorithms” for a reason.) The reason for the focus on functionality? Firstly, because software was and is about doing stuff. Secondly because sufficient performance was hard to achieve, and only thirdly memory efficiency. But then hardware became more powerful. That gave rise to a new mindset: object orientation. And with it functionality was devalued. Data took over its place as the most important aspect. Now discussions revolved around structures motivated by data relationships. (John Beidler gave his book the title “Data Structures and Algorithms: An Object Oriented Approach” instead of the other way around for a reason.) Sure, this data could be embellished with functionality. But nevertheless functionality was second. When you look at (domain) object models what you mostly find is (domain) data object models. The common object oriented approach is: data aka structure over functionality. This is true even for the most modern modeling approaches like Domain Driven Design. Look at the literature and what you find is recommendations on how to get data structures right: aggregates, entities, value objects. I´m not saying this is what object orientation was invented for. But I´m saying that´s what I happen to see across many teams now some 25 years after object orientation became mainstream through C++, Delphi, and Java. But why should we switch back? Because software development cannot become truly agile with a data focus. The reason for that lies in what customers need first: functionality, behavior, operations. To be clear, that´s not why software is built. The purpose of software is to be more efficient than the alternative. Money mainly is spent to get a certain level of quality (e.g. performance, scalability, security etc.). But without functionality being present, there is nothing to work on the quality of. What customers want is functionality of a certain quality. ASAP. And tomorrow new functionality needs to be added, existing functionality needs to be changed, and quality needs to be increased. No customer ever wanted data or structures. Of course data should be processed. Data is there, data gets generated, transformed, stored. But how the data is structured for this to happen efficiently is of no concern to the customer. Ask a customer (or user) whether she likes the data structured this way or that way. She´ll say, “I don´t care.” But ask a customer (or user) whether he likes the functionality and its quality this way or that way. He´ll say, “I like it” (or “I don´t like it”). Build software incrementally From this very natural focus of customers and users on functionality and its quality follows we should develop software incrementally. That´s what Agility is about. Deliver small increments quickly and often to get frequent feedback. That way less waste is produced, and learning can take place much easier (on the side of the customer as well as on the side of developers). An increment is some added functionality or quality of functionality.[1] So as it turns out, Agility is about functionality over whatever. But software developers’ thinking is still stuck in the object oriented mindset of whatever over functionality. Bummer. I guess that (at least partly) explains why Agility always hits a glass ceiling in projects. It´s a clash of mindsets, of cultures. Driving software development by demanding small increases in functionality runs against thinking about software as growing (data) structures sprinkled with functionality. (Excuse me, if this sounds a bit broad-brush. But you get my point.) The need for abstraction In the end there need to be data structures. Of course. Small and large ones. The phrase functionality over data does not deny that. It´s not functionality instead of data or something. It´s just over, i.e. functionality should be thought of first. It´s a tad more important. It´s what the customer wants. That´s why we need a way to design functionality. Small and large. We need to be able to think about functionality before implementing it. We need to be able to reason about it among team members. We need to be able to communicate our mental models of functionality not just by speaking about them, but also on paper. Otherwise reasoning about it does not scale. We learned thinking about functionality in the small using flow charts, Nassi-Shneiderman diagrams, pseudo code, or UML sequence diagrams. That´s nice and well. But it does not scale. You can use these tools to describe manageable algorithms. But it does not work for the functionality triggered by pressing the “1-Click Order” on an amazon product page for example. There are several reasons for that, I´d say. Firstly, the level of abstraction over code is negligible. It´s essentially non-existent. Drawing a flow chart or writing pseudo code or writing actual code is very, very much alike. All these tools are about control flow like code is.[2] In addition all tools are computationally complete. They are about logic which is expressions and especially control statements. Whatever you code in Java you can fully (!) describe using a flow chart. And then there is no data. They are about control flow and leave out the data altogether. Thus data mostly is assumed to be global. That´s shooting yourself in the foot, as I hope you agree. Even if it´s functionality over data that does not mean “don´t think about data”. Right to the contrary! Functionality only makes sense with regard to data. So data needs to be in the picture right from the start - but it must not dominate the thinking. The above tools fail on this. Bottom line: So far we´re unable to reason in a scalable and abstract manner about functionality. That´s why programmers are so driven to start coding once they are presented with a problem. Programming languages are the only tool they´ve learned to use to reason about functional solutions. Or, well, there might be exceptions. Mathematical notation and SQL may have come to your mind already. Indeed they are tools on a higher level of abstraction than flow charts etc. That´s because they are declarative and not computationally complete. They leave out details - in order to deliver higher efficiency in devising overall solutions. We can easily reason about functionality using mathematics and SQL. That´s great. Except for that they are domain specific languages. They are not general purpose. (And they don´t scale either, I´d say.) Bummer. So to be more precise we need a scalable general purpose tool on a higher than code level of abstraction not neglecting data. Enter: Flow Design. Abstracting functionality using data flows I believe the solution to the problem of abstracting functionality lies in switching from control flow to data flow. Data flow very naturally is not about logic details anymore. There are no expressions and no control statements anymore. There are not even statements anymore. Data flow is declarative by nature. With data flow we get rid of all the limiting traits of former approaches to modeling functionality. In addition, nomen est omen, data flows include data in the functionality picture. With data flows, data is visibly flowing from processing step to processing step. Control is not flowing. Control is wherever it´s needed to process data coming in. That´s a crucial difference and needs some rewiring in your head to be fully appreciated.[2] Since data flows are declarative they are not the right tool to describe algorithms, though, I´d say. With them you don´t design functionality on a low level. During design data flow processing steps are black boxes. They get fleshed out during coding. Data flow design thus is more coarse grained than flow chart design. It starts on a higher level of abstraction - but then is not limited. By nesting data flows indefinitely you can design functionality of any size, without losing sight of your data. Data flows scale very well during design. They can be used on any level of granularity. And they can easily be depicted. Communicating designs using data flows is easy and scales well, too. The result of functional design using data flows is not algorithms (too low level), but processes. Think of data flows as descriptions of industrial production lines. Data as material runs through a number of processing steps to be analyzed, enhances, transformed. On the top level of a data flow design might be just one processing step, e.g. “execute 1-click order”. But below that are arbitrary levels of flows with smaller and smaller steps. That´s not layering as in “layered architecture”, though. Rather it´s a stratified design à la Abelson/Sussman. Refining data flows is not your grandpa´s functional decomposition. That was rooted in control flows. Refining data flows does not suffer from the limits of functional decomposition against which object orientation was supposed to be an antidote. Summary I´ve been working exclusively with data flows for functional design for the past 4 years. It has changed my life as a programmer. What once was difficult is now easy. And, no, I´m not using Clojure or F#. And I´m not a async/parallel execution buff. Designing the functionality of increments using data flows works great with teams. It produces design documentation which can easily be translated into code - in which then the smallest data flow processing steps have to be fleshed out - which is comparatively easy. Using a systematic translation approach code can mirror the data flow design. That way later on the design can easily be reproduced from the code if need be. And finally, data flow designs play well with object orientation. They are a great starting point for class design. But that´s a story for another day. To me data flow design simply is one of the missing links of systematic lightweight software design. There are also other artifacts software development can produce to get feedback, e.g. process descriptions, test cases. But customers can be delighted more easily with code based increments in functionality. ? No, I´m not talking about the endless possibilities this opens for parallel processing. Data flows are useful independently of multi-core processors and Actor-based designs. That´s my whole point here. Data flows are good for reasoning and evolvability. So forget about any special frameworks you might need to reap benefits from data flows. None are necessary. Translating data flow designs even into plain of Java is possible. ?

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  • CodePlex Daily Summary for Friday, June 22, 2012

    CodePlex Daily Summary for Friday, June 22, 2012Popular ReleasesXDA ROM HUB: XDA ROM HUB v0.7: Added custom ROM list. Xperia Active and Arc/s will be added on 0.7.1BlackJumboDog: Ver5.6.5: 2012.06.22 Ver5.6.5  (1) FTP??????? EPSV ?? EPRT ???????PrepareQuery for MVC: PrepareQuery Demo with assemplies: ??????????????? ?????? ?????????? ? ???????? ??????. ????? ?? ?????? ??? ?????? ????????? ????? nuget-??????. Dynamic Linq Query Builder for ASP.NET MVC ??????? ?? Dynamic Linq Query Builder, ? ?????? ??????????? ?????????????. ?????? ???? ??????? ????? ???????????? ? ?????? ?? ????????? ?????????????.DotNetNuke® Form and List: 06.00.01: DotNetNuke Form and List 06.00.01 Changes in 06.00.01 Icons are shown in module action buttons (workaraound to core issue with IconAPI) Fix to Token2XSL Editor, changing List type raised exception MakeTumbnail and ShowXml handlers had been missing in install package Updated help texts for better understanding of filter statement, token support in email subject and css style Major changes for fnL 6.0: DNN 6 Form Patterns including modal PopUps and Tabs http://www.dotnetnuke.com/Po...MVVM Light Toolkit: V4RTM (binaries only) including Windows 8 RP: This package contains all the latest DLLs for MVVM Light V4 RTM. It includes the DLLs for Windows 8 Release Preview. An updated Nuget package is also available at http://nuget.org/packages/MvvmLightLibs An installer with binaries, snippets and templates will follow ASAP.Weapsy - ASP.NET MVC CMS: 1.0.0: - Some changes to Layout and CSS - Changed version number to 1.0.0.0 - Solved Cache and Session items handler error in IIS 7 - Created the Modules, Plugins and Widgets Areas - Replaced CKEditor with TinyMCE - Created the System Info page - Minor changesTabular AMO 2012: Tabular AMO 2012 V2 - release 1.0: This is the first stable release of Tabular AMO 2012 V2. In this download you will find the AMO2Tabular V2 library and the AdventureWorks Tabular AMO 2012 sample project to build a tabular model using the library.AcDown????? - AcDown Downloader Framework: AcDown????? v3.11.7: ?? ●AcDown??????????、??、??????。????,????,?????????????????????????。???????????Acfun、????(Bilibili)、??、??、YouTube、??、???、??????、SF????、????????????。 ●??????AcPlay?????,??????、????????????????。 ● AcDown??????????????????,????????????????????????????。 ● AcDown???????C#??,????.NET Framework 2.0??。?????"Acfun?????"。 ????32??64? Windows XP/Vista/7/8 ??:????????Windows XP???,?????????.NET Framework 2.0???(x86),?????"?????????"??? ??????????????,??????????: ??"AcDown?????"????????? ...NShader - HLSL - GLSL - CG - Shader Syntax Highlighter AddIn for Visual Studio: NShader 1.3 - VS2010 + VS2012: This is a small maintenance release to support new VS2012 as well as VS2010. This release is also fixing the issue The "Comment Selection" include the first line after the selection If the new NShader version doesn't highlight your shader, you can try to: Remove the registry entry: HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\11.0\FontAndColors\Cache Remove all lines using "fx" or "hlsl" in file C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\CommonExtensions\Micr...asp.net membership: v1.0 Membership Management: Abmemunit is a Membership Management Project where developer can use their learning purposes of various issues related to ASP.NET, MVC, ASP.NET membership, Entity Framework, Code First, Ajax, Unit Test, IOC Container, Repository, and Service etc. Though it is a very simple project and all of these topics are used in an easy manner gathering from various big projects, it can easily understand. User End Functional Specification The functionalities of this project are very simple and straight...JSON Toolkit: JSON Toolkit 4.0: Up to 2.5x performance improvement in stringify operations Up to 1.7x performance improvement in parse operations Improved error messages when parsing invalid JSON strings Extended support to .Net 2.0, .Net 3.5, .Net 4.0, Silverlight 4, Windows Phone, Windows 8 metro apps and Xbox JSON namespace changed to ComputerBeacon.Json namespaceXenta Framework - extensible enterprise n-tier application framework: Xenta Framework 1.8.0: System Requirements OS Windows 7 Windows Vista Windows Server 2008 Windows Server 2008 R2 Web Server Internet Information Service 7.0 or above .NET Framework .NET Framework 4.0 WCF Activation feature HTTP Activation Non-HTTP Activation for net.pipe/net.tcp WCF bindings ASP.NET MVC ASP.NET MVC 3.0 Database Microsoft SQL Server 2005 Microsoft SQL Server 2008 Microsoft SQL Server 2008 R2 Additional Deployment Configuration Started Windows Process Activation service Start...CrashReporter.NET : Exception reporting library for C# and VB.NET: CrashReporter.NET 1.1: Added screenshot support that takes screenshot of user's desktop on application crash and provides option to include screenshot with crash report. Added Windows version in crash reports. Added email field and exception type field in crash report dialog. Added exception type in crash reports. Added screenshot tab that shows crash screenshot.MFCMAPI: June 2012 Release: Build: 15.0.0.1034 Full release notes at SGriffin's blog. If you just want to run the MFCMAPI or MrMAPI, get the executables. If you want to debug them, get the symbol files and the source. The 64 bit builds will only work on a machine with Outlook 2010 64 bit installed. All other machines should use the 32 bit builds, regardless of the operating system. Facebook BadgeMonoGame - Write Once, Play Everywhere: MonoGame 2.5.1: Release Notes The MonoGame team are pleased to announce that MonoGame v2.5.1 has been released. This release contains important bug fixes and minor updates. Recent additions include project templates for iOS and MacOS. The MonoDevelop.MonoGame AddIn also works on Linux. We have removed the dependency on the thirdparty GamePad library to allow MonoGame to be included in the debian/ubuntu repositories. There have been a major bug fix to ensure textures are disposed of correctly as well as some ...????: ????2.0.2: 1、???????????。 2、DJ???????10?,?????????10?。 3、??.NET 4.5(Windows 8)????????????。 4、???????????。 5、??????????????。 6、???Windows 8????。 7、?????2.0.1???????????????。 8、??DJ?????????。Azure Storage Explorer: Azure Storage Explorer 5 Preview 1 (6.17.2012): Azure Storage Explorer verison 5 is in development, and Preview 1 provides an early look at the new user interface and some of the new features. Here's what's new in v5 Preview 1: New UI, similar to the new Windows Azure HTML5 portal Support for configuring and viewing storage account logging Support for configuring and viewing storage account monitoring Uses the Windows Azure 1.7 SDK libraries Bug fixes????????API for .Net SDK: SDK for .Net ??? Release 2: 6?20????? ?? - FrindesInActive???????json?????????,???????????。??。 6?19????? ?? - ???????????????,???????0?????????。 ?? - ???Entity?????Suggestion??????????????JSON????????。 ?? - ???OAuth?Request??????AccessToken???SourceKey????QueryString?????????。 6?17????? ??? - .net 4.0 SDK??Dynamic??????????????????API?? ??? - ?Utility?????????API??????DateTime???ParseUTCDate ?? - ?????????????Json.net???,???SDK????Json.net?????。 ?? - ???Client??????API???GetCommand?PostCommand,??????????????...KangaModeling: Kanga Modeling 1.0: This is the public release 1.0 of Kanga Modeling. -Cosmos (C# Open Source Managed Operating System): Release 92560: Prerequisites Visual Studio 2010 - Any version including Express. Express users must also install Visual Studio 2010 Integrated Shell runtime VMWare - Cosmos can run on real hardware as well as other virtualization environments but our default debug setup is configured for VMWare. VMWare Player (Free). or Workstation VMWare VIX API 1.11New ProjectsBilling and Collection .NET (BACS.Net): BACS.NET is a project to create a billing and collections system for financial users in a small, parochial school environment.Bing Wallpaper: Gets current picture from Bing and sets it as wallpaper, with optional correction of aspect ratioBlogForFree: This is a simple blog for free users.Break Time: Break-Time reminds you to take a mental and physical break from sitting in front of your computer for too long. Yes, a glorified timer but better, I promise!BTasks: Sistema para controle de tarefas.Calculate Library: Calculate Library is a library capable of parsing math expressions from strings and evaluating the value at run time. ControleMatricula: Este projeto tem por objetivo realizar o gerenciamento de matriculas de cursos escolares.EagleTrack2012: Application for tracking achievements for scout type programsFury OS: FuryOS isn't reinventing the wheel. Fury is a new simple COSMOS OS written to run on real hardware with a GUI and Dynamite#/D# programming language. Take a lookGeneric Compact Input Language: Generic Compact Input Language (GCIL) is a library supporting interpretation of a customizable input language. hgdd06212012: fdghgdd062120123: asdhgdd062120125: weJava to CSharp: This is a tiny project with an intention to make it large. Currently it can be used to convert very tiny and simple Java programs to C# .ModelStore: This project aims to create a generic engine and persistence store for modeling operations.MsSqlMetaDataProvider: Simple wrapper around system views using entity framework model. Intended to be used for auto code generation and template consumption.Multiple Select Refinement Panel Web Part: Multiple Select Refinement Panel web part is developed by extending the out of the box Refinement Panel. It is built over a TreeView control with all the nodes Note+: Coming SoonPrairieAsunder: PrairieAsunder is an HTML5 + MVC3 application that streams local music from Central Illinois. The code is a fork of the Chavah Messianic Radio codebaseRemoteCommand Add-On Module for Mayhem: RemoteCommand is and add-on module for the CodePlex project Mayhem. RemoteCommand allows remote systems, such as IVR's, to trigger events .Results Per Page Search Core Results Web Part: Results Per Page Search Core Results web part is developed by extending the out of the box Search Core Results web part.Secure Socket Protocol: Create a secured Server/Client the easy way with SSPSkype Screen Saver: A handy addition for those who use Skype and like to use headphones. And for those who are mute speakers - too..Tabular AMO 2012: Tabular AMO 2012 is about creating and managing tabular models using the AMO api. It is a developer’s sample, for those interested in managing Analysis Servicestestdd062120126: sdtesttom06212012git01: gfdgfdgfdXDesigner.Development: .Tools for developer , Support VS.NET , VB6.0 or others, Future: 1.Source code line count . 2.Add or remove comment batch. 3.Copy source file clearly. ......

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  • Why Does .Hide()ing and .Show()ing Panels in wxPython Result in the Sizer Changing the Layout?

    - by MetaHyperBolic
    As referenced in my previous question, I am trying to make something slightly wizard-like in function. I have settled on a single frame with a sizer added to it. I build panels for each of the screens I would like users to see, add them to the frame's sizer, then switch between panels by .Hide()ing one panel, then calling a custom .ShowYourself() on the next panel. Obviously, I would like the buttons to remain in the same place as the user progresses through the process. I have linked together two panels in an infinite loop by their "Back" and "Next" buttons so you can see what is going on. The first panel looks great; tom10's code worked on that level, as it eschewed my initial, over-fancy attempt with borders flying every which way. And then the second panel seems to have shrunk down to the bare minimum. As we return to the first panel, the shrinkage has occurred here as well. Why does it look fine on the first panel, but not after I return there? Why is calling .Fit() necessary if I do not want a 10 pixel by 10 pixel wad of grey? And if it is necessary, why does .Fit() give inconsistent results? This infinite loop seems to characterize my experience with this: I fix the layout on a panel, only to find that switching ruins the layout for other panels. I fix that problem, by using sizer_h.Add(self.panel1, 0) instead of sizer_h.Add(self.panel1, 1, wx.EXPAND), and now my layouts are off again. So far, my "solution" is to add a mastersizer.SetMinSize((475, 592)) to each panel's master sizer (commented out in the code below). This is a cruddy solution because 1) I have had to find the numbers that work by trial and error (-5 pixels for the width, -28 pixels for the height). 2) I don't understand why the underlying issue still happens. What's the correct, non-ugly solution? Instead of adding all of the panels to the frame's sizer at once, should switching panels involve .Detach()ing that panel from the frame's sizer and then .Add()ing the next panel to the frame's sizer? Is there a .JustMakeThisFillThePanel() method hiding somewhere I have missed in both the wxWidgets and the wxPython documents online? I'm obviously missing something in my mental model of layout. Here's a TinyURL link, if I can't manage to embed the . Minimalist code pasted below. import wx import sys class My_App(wx.App): def OnInit(self): self.frame = My_Frame(None) self.frame.Show() self.SetTopWindow(self.frame) return True def OnExit(self): print 'Dying ...' class My_Frame(wx.Frame): def __init__(self, image, parent=None,id=-1, title='Generic Title', pos=wx.DefaultPosition, style=wx.CAPTION | wx.STAY_ON_TOP): size = (480, 620) wx.Frame.__init__(self, parent, id, 'Program Title', pos, size, style) sizer_h = wx.BoxSizer(wx.HORIZONTAL) self.panel0 = User_Interaction0(self) sizer_h.Add(self.panel0, 1, wx.EXPAND) self.panel1 = User_Interaction1(self) sizer_h.Add(self.panel1, 1, wx.EXPAND) self.SetSizer(sizer_h) self.panel0.ShowYourself() def ShutDown(self): self.Destroy() class User_Interaction0(wx.Panel): def __init__(self, parent, id=-1): wx.Panel.__init__(self, parent, id) # master sizer for the whole panel mastersizer = wx.BoxSizer(wx.VERTICAL) #mastersizer.SetMinSize((475, 592)) mastersizer.AddSpacer(15) # build the top row txtHeader = wx.StaticText(self, -1, 'Welcome to This Boring\nProgram', (0, 0)) font = wx.Font(16, wx.DEFAULT, wx.NORMAL, wx.BOLD) txtHeader.SetFont(font) txtOutOf = wx.StaticText(self, -1, '1 out of 7', (0, 0)) rowtopsizer = wx.BoxSizer(wx.HORIZONTAL) rowtopsizer.Add(txtHeader, 3, wx.ALIGN_LEFT) rowtopsizer.Add((0,0), 1) rowtopsizer.Add(txtOutOf, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowtopsizer, 0, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the middle row text = 'PANEL 0\n\n' text = text + 'This could be a giant blob of explanatory text.\n' txtBasic = wx.StaticText(self, -1, text) font = wx.Font(11, wx.DEFAULT, wx.NORMAL, wx.NORMAL) txtBasic.SetFont(font) mastersizer.Add(txtBasic, 1, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the bottom row btnBack = wx.Button(self, -1, 'Back') self.Bind(wx.EVT_BUTTON, self.OnBack, id=btnBack.GetId()) btnNext = wx.Button(self, -1, 'Next') self.Bind(wx.EVT_BUTTON, self.OnNext, id=btnNext.GetId()) btnCancelExit = wx.Button(self, -1, 'Cancel and Exit') self.Bind(wx.EVT_BUTTON, self.OnCancelAndExit, id=btnCancelExit.GetId()) rowbottomsizer = wx.BoxSizer(wx.HORIZONTAL) rowbottomsizer.Add(btnBack, 0, wx.ALIGN_LEFT) rowbottomsizer.AddSpacer(5) rowbottomsizer.Add(btnNext, 0) rowbottomsizer.AddSpacer(5) rowbottomsizer.AddStretchSpacer(1) rowbottomsizer.Add(btnCancelExit, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowbottomsizer, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # finish master sizer mastersizer.AddSpacer(15) self.SetSizer(mastersizer) self.Raise() self.SetPosition((0,0)) self.Fit() self.Hide() def ShowYourself(self): self.Raise() self.SetPosition((0,0)) self.Fit() self.Show() def OnBack(self, event): self.Hide() self.GetParent().panel1.ShowYourself() def OnNext(self, event): self.Hide() self.GetParent().panel1.ShowYourself() def OnCancelAndExit(self, event): self.GetParent().ShutDown() class User_Interaction1(wx.Panel): def __init__(self, parent, id=-1): wx.Panel.__init__(self, parent, id) # master sizer for the whole panel mastersizer = wx.BoxSizer(wx.VERTICAL) #mastersizer.SetMinSize((475, 592)) mastersizer.AddSpacer(15) # build the top row txtHeader = wx.StaticText(self, -1, 'Read about This Boring\nProgram', (0, 0)) font = wx.Font(16, wx.DEFAULT, wx.NORMAL, wx.BOLD) txtHeader.SetFont(font) txtOutOf = wx.StaticText(self, -1, '2 out of 7', (0, 0)) rowtopsizer = wx.BoxSizer(wx.HORIZONTAL) rowtopsizer.Add(txtHeader, 3, wx.ALIGN_LEFT) rowtopsizer.Add((0,0), 1) rowtopsizer.Add(txtOutOf, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowtopsizer, 0, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the middle row text = 'PANEL 1\n\n' text = text + 'This could be a giant blob of boring text.\n' txtBasic = wx.StaticText(self, -1, text) font = wx.Font(11, wx.DEFAULT, wx.NORMAL, wx.NORMAL) txtBasic.SetFont(font) mastersizer.Add(txtBasic, 1, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # build the bottom row btnBack = wx.Button(self, -1, 'Back') self.Bind(wx.EVT_BUTTON, self.OnBack, id=btnBack.GetId()) btnNext = wx.Button(self, -1, 'Next') self.Bind(wx.EVT_BUTTON, self.OnNext, id=btnNext.GetId()) btnCancelExit = wx.Button(self, -1, 'Cancel and Exit') self.Bind(wx.EVT_BUTTON, self.OnCancelAndExit, id=btnCancelExit.GetId()) rowbottomsizer = wx.BoxSizer(wx.HORIZONTAL) rowbottomsizer.Add(btnBack, 0, wx.ALIGN_LEFT) rowbottomsizer.AddSpacer(5) rowbottomsizer.Add(btnNext, 0) rowbottomsizer.AddSpacer(5) rowbottomsizer.AddStretchSpacer(1) rowbottomsizer.Add(btnCancelExit, 0, wx.ALIGN_RIGHT) mastersizer.Add(rowbottomsizer, flag=wx.EXPAND | wx.LEFT | wx.RIGHT, border=15) # finish master sizer mastersizer.AddSpacer(15) self.SetSizer(mastersizer) self.Raise() self.SetPosition((0,0)) self.Fit() self.Hide() def ShowYourself(self): self.Raise() self.SetPosition((0,0)) self.Fit() self.Show() def OnBack(self, event): self.Hide() self.GetParent().panel0.ShowYourself() def OnNext(self, event): self.Hide() self.GetParent().panel0.ShowYourself() def OnCancelAndExit(self, event): self.GetParent().ShutDown() def main(): app = My_App(redirect = False) app.MainLoop() if __name__ == '__main__': main()

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  • Red Gate Coder interviews: Robin Hellen

    - by Michael Williamson
    Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

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  • Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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