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  • What is logical cohesion, and why is it bad or undesirable?

    - by Matt Fenwick
    From the c2wiki page on coupling & cohesion: Cohesion (interdependency within module) strength/level names : (from worse to better, high cohesion is good) Coincidental Cohesion : (Worst) Module elements are unrelated Logical Cohesion : Elements perform similar activities as selected from outside module, i.e. by a flag that selects operation to perform (see also CommandObject). i.e. body of function is one huge if-else/switch on operation flag Temporal Cohesion : operations related only by general time performed (i.e. initialization() or FatalErrorShutdown?()) Procedural Cohesion : Elements involved in different but sequential activities, each on different data (usually could be trivially split into multiple modules along linear sequence boundaries) Communicational Cohesion : unrelated operations except need same data or input Sequential Cohesion : operations on same data in significant order; output from one function is input to next (pipeline) Informational Cohesion: a module performs a number of actions, each with its own entry point, with independent code for each action, all performed on the same data structure. Essentially an implementation of an abstract data type. i.e. define structure of sales_region_table and its operators: init_table(), update_table(), print_table() Functional Cohesion : all elements contribute to a single, well-defined task, i.e. a function that performs exactly one operation get_engine_temperature(), add_sales_tax() (emphasis mine). I don't fully understand the definition of logical cohesion. My questions are: what is logical cohesion? Why does it get such a bad rap (2nd worst kind of cohesion)?

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  • bad request error 400 while using python requests.post function

    - by Toussah
    I'm trying to make a simple post request via the requests library of Python and I get a bad request error (400) while my url is supposedly correct since I can use it to perform a get. I'm very new in REST requests, I read many tutorials and documentation but I guess there are still things I don't get so my error could be basic. Maybe a lack of understanding on the type of url I'm supposed to send via POST. Here my code : import requests v_username = "username" v_password = "password" v_headers = {'content-type':'application/rdf+xml'} url = 'https://my.url' params = {'param': 'val_param'} payload = {'data': 'my_data'} r = requests.post(url, params = params, auth=(v_username, v_password), data=payload, headers=v_headers, verify=False) print r I used the example of the requests documentation.

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  • Bad Design? Constructor of composition uses `this`

    - by tanascius
    Example: class MyClass { Composition m_Composition; void MyClass() { m_Composition = new Composition( this ); } } I am interested in using depenency-injection here. So I will have to refactor the constructor to something like: void MyClass( Composition composition ) { m_Composition = composition; } However I get a problem now, since the Composition-object relies on the object of type MyClass which is just created. Can a dependency container resolve this? Is it supposed to do so? Or is it just bad design from the beginning on?

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  • Multiple classes in a single .cs file - good or bad?

    - by Sergio
    Is it advisable to create multiple classes within a .cs file or should each .cs file have an individual class? For example: public class Items { public class Animal { } public class Person { } public class Object { } } Dodging the fact for a minute that this is a poor example of good architecture, is having more than a single class in a .cs file a code smell?

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  • How would you know if you've written readable and easily maintainable code?

    - by KyelJmD
    How would one know if the code he has created is easily maintainable and readable? Of course in your point of view (the one who actually wrote the code) your code is readable and maintainable, but we should be true to ourselves here. How would we know if we've written pretty messy and unmaintainable code? Are there any constructs or guidelines to know if we have developed a messy piece of software?

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  • What is the oldest living piece of unaltered production code? [closed]

    - by user1598390
    It's come to my mind that parts of the code in, say, Unix, has maybe passed unaltered from one version or flavor into another. Maybe some pieces of the source code of the ls command is the same, unaltered, than was written years ago. Have any of you read or learn about this ? What would be the oldest living piece of unaltered production code still running, passing from version through version of a program or system ? Will the code we write outlive us for decades ?

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  • OS8- AK8- The bad news...

    - by Steve Tunstall
    Ok I told you I would give you the bad news of AK8 to go along with all the cool new stuff, so here it is. It's not that bad, really, just things you need to be aware of. First, the 2013.1 code is being called OS8, AK8 and 2013.1 by different people. I mean different people INSIDE Oracle!! It was supposed to be easy, but it never is. So for the rest of this blog entry, I'm calling it AK8. AK8 is not compatible with the 7x10 series. Ever. The 7x10 series is not supported with AK8, and if you try to upgrade one, it will fail at the healthcheck. All 7x20 series, all of them regardless of age, are supported with AK8. Drive trays. Let's talk about drive trays and SAS cards. The older drive trays for the 7x20 series were called the "Riverwalk 2" or "DS2" trays. They were technically the "J4410" series JBODs that Sun used to sell a la carte before we stopped selling JBODs. Don't get me started on that, it still makes me mad. We used these for many years, and you can still buy them right now until December 15th, 2013, when they will no longer be sold. The DS2 tray only came as a 4u, 24 drive shelf. It held 3.5" drives, and you had a choice of 2TB, 3TB, 300GB or 600GB drives. The SAS HBA in the 7x20 series was called a "Thebe" card, with a part # of 7105394. The 7420, for example, came standard with two of these "Thebe" cards for connecting to the disk trays. Two Thebe cards could handle up to 12 trays, so one would add two more cards to go to 24 trays, or have up to six Thebe cards to handle 36 trays. This card was for external SAS only. It did not connect to the internal OS drives or the Readzillas, both of which used the internal SCSI controller of the server. These Riverwalk 2 trays ARE supported with AK8. You can upgrade your older 7420 or 7320, no problem, as-is. The much older Riverwalk 1 trays or J4400 trays are NOT supported by AK8. However, they were only used by the 7x10 series, and we already said that the 7x10 series was not supported. Here's where it gets tricky. Since last January, we have been selling the new style disk trays. We call them the "DE2-24P" and the "DE2-24C" trays. The "C" tray is for capacity drives, which are 3.5" 3TB or 4TB drives. The "P" trays are for performance drives, which are 2.5" 300GB and 900GB drives. These trays are NOT Riverwalk 2 trays, even though the "C" series may kind of look like it. Different manufacturer and different firmware. They are not new. Like I said, we've been selling them with the 7x20 series since last January. They are the only disk trays we will be selling going forward. Of course, AK8 supports them. So what's the problem? The problem is going to be for people who have to mix drive trays. Remember, your older 7x20 series has Thebe SAS2 HBAs. These have 2 SAS ports per card.  The new ZS3-2 and ZS3-4 systems, however, have the new "Thebe2" SAS2 HBAs. These Thebe2 cards have 4 ports per card. This is very cool, as we can now do more SAS channels with less cards. Instead of needing 4 SAS cards to grow to 24 trays like we did with the old Thebe cards, I can now do 24 trays with only 2 Thebe2 cards. This means more IO slots for fun things like Infiniband and 10G. So far, so good, right? These Thebe2 cards work with any disk tray. You can even mix older DS2 trays with the newer DE2 trays in the same system, as long as you have Thebe2 cards. Ah, there's your problem. You don't have Thebe2 cards in your old 7420, do you? Well, I told you the bad news wasn't that bad, right? We can take out your Thebe cards and replace them with Thebe2. You can then plug your older DS2 trays right back in, and also now get newer DE2 trays going forward. However, it's important that the trays are on different SAS channels. You can mix them in the same system, but not on the same channel. Ask your local SC if you need help with the new cable layout. By the way, the new ZS3-2 and ZS3-4 systems also include a new IO card called "Erie" cards. These are for INTERNAL SAS to the OS drives and the Readzillas. So those are now SAS2 instead of SATA like the older models. Yes, the Erie card uses an IO slot, but that's OK, because the Thebe2 cards allow us to use less SAS HBAs to grow the system, right? That's it. Not too much bad news and really not that bad. AK8 does not support the 7x10 series, and you may need new Thebe2 cards in your older systems if you want to add on newer DE2 trays. I think we can all agree that there are worse things out there. Like our Congress.   Next up.... More good news and cool AK8 tricks. Such as virtual NICS. 

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  • How do I take responsibility for my code when colleague makes unnecessary improvements without notice?

    - by Jesslyn
    One of my teammates is a jack of all trades in our IT shop and I respect his insight. However, sometimes he reviews my code (he's second in command to our team leader, so that's expected) without a heads up. So sometimes he reviews my changes before they complete the end goal and makes changes right away... and has even broken my work once. Other times, he has made unnecessary improvements to some of my code that is 3+ months old. This annoys me for a few reasons: I am not always given a chance to fix my mistakes He has not taken the time to ask me what I was trying to accomplish when he is confused, which could affect his testing or changes I don't always think his code is readable Deadlines are not an issue and his current workload doesn't require any work in my projects other than reviewing my code changes. Anyways, I have told him in the past to please keep me posted if he sees something in my work that he wants to change so that I could take ownership of my code (maybe I should have said "shortcomings") and he's not been responsive. I fear that I may come off as aggressive when I ask him to explain his changes to me. He's just a quiet person who keeps to himself, but his actions continue. I don't want to banish him from making code changes (not like I could), because we are a team--but I want to do my part to help our team. Added clarifications: We share 1 development branch. I do not wait until all my changes complete a single task because I risk losing some significant work--so I make sure my changes build and do not break anything. My concern is that my teammate doesn't explain the reason or purpose behind his changes. I don't think he should need my blessing, but if we disagree on an approach I thought it would be best to discuss the pros and cons and make a decision once we both understand what is going on. I have not discussed this with our team lead yet as I would prefer to resolve personal disagreements without getting management involved unless it is necessary. Since my concern seemed more of personal issue than a threat to our work, I chose to not bother the team lead. I am working on code review process ideas--to help promote the benefits of more organized code reviews without making it all about my pet peeves.

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  • Multiple classes in a single .cs file - good or bad?

    - by Sergio
    Is it advisable to create multiple classes within a .cs file or should each .cs file have an individual class? For example: public class Items { public class Animal { } public class Person { } public class Object { } } Dodging the fact for a minute that this is a poor example of good architecture, is having more than a single class in a .cs file a code smell?

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  • The package is of bad quality - google chrome

    - by hafichuk
    I'm doing a fresh install of 12.10 and am trying to install Google Chrome. I've downloaded the deb from http://chrome.google.com and am installing it through the Ubuntu Software Centre. I'm getting a message: The package is of bad quality (same as What is a "bad quality" package?) In the expanded section, the "error" states: E: google-chrome-stable: file-in-etc-not-marked-as-conffile etc/cron.daily/google-chrome Is it safe to click on the "Ignore and Install" button?

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  • Writing a code example

    - by Stefano Borini
    I would like to have your feedback regarding code examples. One of the most frustrating experiences I sometimes have when learning a new technology is finding useless examples. I think an example as the most precious thing that comes with a new library, language, or technology. It must be a starting point, a wise and unadulterated explanation on how to achieve a given result. A perfect example must have the following characteristics: Self contained: it should be small enough to be compiled or executed as a single program, without dependencies or complex makefiles. An example is also a strong functional test if you correctly installed the new technology. The more issues could arise, the more likely is that something goes wrong, and the more difficult is to debug and solve the situation. Pertinent: it should demonstrate one, and only one, specific feature of your software/library, involving the minimal additional behavior from external libraries. Helpful: the code should bring you forward, step by step, using comments or self-documenting code. Extensible: the example code should be a small “framework” or blueprint for additional tinkering. A learner can start by adding features to this blueprint. Recyclable: it should be possible to extract parts of the example to use in your own code Easy: An example code is not the place to show your code-fu skillz. Keep it easy. helpful acronym: SPHERE. Prototypical examples of violations of those rules are the following: Violation of self-containedness: an example spanning multiple files without any real need for it. If your example is a python program, keep everything into a single module file. Don’t sub-modularize it. In Java, try to keep everything into a single class, unless you really must partition some entity into a meaningful object you need to pass around (and java mandates one class per file, if I remember correctly). Violation of Pertinency: When showing how many different shapes you can draw, adding radio buttons and complex controls with all the possible choices for point shapes is a bad idea. You de-focalize your example code, introducing code for event handling, controls initialization etc., and this is not part the feature you want to demonstrate, they are unnecessary noise in the understanding of the crucial mechanisms providing the feature. Violation of Helpfulness: code containing dubious naming, wrong comments, hacks, and functions longer than one page of code. Violation of Extensibility: badly factored code that have everything into a single function, with potentially swappable entities embedded within the code. Example: if an example reads data from a file and displays it, create a method getData() returning a useful entity, instead of opening the file raw and plotting the stuff. This way, if the user of the library needs to read data from a HTTP server instead, he just has to modify the getData() module and use the example almost as-is. Another violation of Extensibility comes if the example code is not under a fully liberal (e.g. MIT or BSD) license. Violation of Recyclability: when the code layout is so intermingled that is difficult to easily copy and paste parts of it and recycle them into another program. Again, licensing is also a factor. Violation of Easiness: Yes, you are a functional-programming nerd and want to show how cool you are by doing everything on a single line of map, filter and so on, but that could not be helpful to someone else, who is already under pressure to understand your library, and now has to understand your code as well. And in general, the final rule: if it takes more than 10 minutes to do the following: compile the code, run it, read the source, and understand it fully, it means that the example is not a good one. Please let me know your opinion, either positive or negative, or experience on this regard.

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  • code review: Is it subjective or objective(quantifiable) ?

    - by Ram
    I am putting together some guidelines for code reviews. We do not have one formal process yet, and trying to formalize it. And our team is geographically distributed We are using TFS for source control (used it for tasks/bug tracking/project management as well, but migrated that to JIRA) with VS2008 for development. What are the things you look for when doing a code review ? These are the things I came up with Enforce FXCop rules (we are a Microsoft shop) Check for performance (any tools ?) and security (thinking about using OWASP- code crawler) and thread safety Adhere to naming conventions The code should cover edge cases and boundaries conditions Should handle exceptions correctly (do not swallow exceptions) Check if the functionality is duplicated elsewhere method body should be small(20-30 lines) , and methods should do one thing and one thing only (no side effects/ avoid temporal coupling -) Do not pass/return nulls in methods Avoid dead code Document public and protected methods/properties/variables What other things do you generally look for ? I am trying to see if we can quantify the review process (it would produce identical output when reviewed by different persons) Example: Saying "the method body should be no longer than 20-30 lines of code" as opposed to saying "the method body should be small" Or is code review very subjective ( and would differ from one reviewer to another ) ? The objective is to have a marking system (say -1 point for each FXCop rule violation,-2 points for not following naming conventions,2 point for refactoring etc) so that developers would be more careful when they check in their code.This way, we can identify developers who are consistently writing good/bad code.The goal is to have the reviewer spend about 30 minutes max, to do a review (I know this is subjective, considering the fact that the changeset/revision might include multiple files/huge changes to the existing architecture etc , but you get the general idea, the reviewer should not spend days reviewing someone's code) What other objective/quantifiable system do you follow to identify good/bad code written by developers? Book reference: Clean Code: A handbook of agile software craftmanship by Robert Martin

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  • What Did You Do? is a Bad Question

    - by Ajarn Mark Caldwell
    Brian Moran (blog | Twitter) did a great presentation today for the PASS Professional Development Virtual Chapter on The Art of Questions.  One of the points that Brian made was that there are good questions and bad (or at least not-as-good) questions.  Good questions tend to open-up the conversation and engender positive reactions (perhaps even trust and respect) between the participants; and bad questions tend to close-down a conversation either through the narrow list of possible responses (e.g. strictly Yes/No) or through the negative reactions they can produce.  And this explains why I so frequently had problems troubleshooting real-time problems with users in the past.  I’ll explain that in more detail below, but before we go on, let me recommend that you watch the recording of Brian’s presentation to learn why the question Why is often problematic in the U.S. and yet we so often resort to it. For a short portion (3 years) of my career, I taught basic computer skills and Office applications in an adult vocational school, and this gave me ample opportunity to do live troubleshooting of user challenges with computers.  And like many people who ended up in computer related jobs, I also have had numerous times where I was called upon by less computer-savvy individuals to help them with some challenge they were having, whether it was part of my job or not.  One of the things that I noticed, especially during my time as a teacher, was that when I was helping somebody, typically the first question I would ask them was, “What did you do?”  This seemed to me like a good way to start my detective work trying to figure out what happened, what went wrong, how to fix it, and how to help the person avoid it again in the future.  I always asked it in a polite tone of voice as I was just trying to gather the facts before diving in deeper.  However; 99.999% of the time, I always got the same answer, “Nothing!”  For a long time this frustrated me because (remember I’m in detective mode at that point) I knew it could not possibly be true.  They HAD to have done SOMETHING…just tell me what were the last actions you took before this problem presented itself.  But no, they always stuck with “Nothing”.  At which point, with frustration growing, and not a little bit of disdain for their lack of helpfulness, I would usually ask them to move aside while I took over their machine and got them out of whatever they had gotten themselves into.  After a while I just grew used to the fact that this was the answer I would usually receive, but I always kept asking because for the .001% of the people who would actually tell me, I could then help them understand what went wrong and how to avoid it in the future. Now, after hearing Brian’s talk, I understand what the problem was.  Even though I meant to just be in an information gathering mode, the words I was using, “What did YOU do?” have such a strong negative connotation that people would instinctively go into defense-mode and stop sharing information that might make them look bad.  Many of them probably were not even consciously aware that they had gone on the defensive, but the self-preservation instinct, especially self-preservation of the ego, is so strong that people would end up there without even realizing it. So, if “What did you do” is a bad question, what would have been better?  Well, one suggestion that Brian makes in his talk is something along the lines of, “Can you tell me what led up to this?” or “what was happening on the computer right before this came up?”  It’s subtle, but the point is to take the focus off of the person and their behavior; instead depersonalizing it and talk about events from more of a 3rd-party observer point of view.  With this approach, people will be more likely to talk about what the computer did and what they did in response to it without feeling the interrogation spotlight is on them.  They are also more likely to mention other events that occurred around the same time that may or may not be related, but which could certainly help you troubleshoot a larger problem if it is not just user actions.  And that is the ultimate goal of your asking the questions.  So yes, it does matter how you ask the question; and there are such things as good questions and bad questions.  Excellent topic Brian!  Thanks for getting the thinking gears churning! (Cross-posted to the Professional Development Virtual Chapter blog.)

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  • Does software rot refer primarily to performance, or to messy code?

    - by Kazark
    Wikipedia's definition of software rot focuses on the performance of the software. This is a different usage than I am used to; I had thought of it much more in terms of the cleanliness and design of the code—in terms of the code's having all the standard quality characteristics: readability, maintainability, etc. Now, performance is likely to go down when the code becomes unreadable, because no one knows what is going on. But does the term software rot have special reference to performance? or am I right in thinking it refers to the cleanliness of the code? or is this perhaps a case of multiple senses of the term being in common usage—from the user's perspective, it has do with performance; but for the software craftsman, it has to do more specifically with how the code reads?

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  • Are there any books dedicated to writing test code? [on hold]

    - by joshin4colours
    There are many programming books dedicated to useful programming and engineering topics, like working with legacy code or particular languages. The best of these books become "standard" or "canonical" references for professional programmers. Are there any books like this (or that could be like this) for writing test code? I don't mean books about Test-Driven Development, nor do I mean books about writing good (clean) code in general. I'm looking for books that discuss test code specifically (unit-level, integration-level, UI-level, design patterns, code structures and organization, etc.)

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  • What is missing and should be added to Code Complete 3rd Edition? [closed]

    - by Peter Turner
    It's been quite a few years since Code Complete was published. I really love the book, I keep it in the bathroom at the office and read a little out of it once or twice a day. What developments in computer software... development need to be added to Code Complete 3e, and for the sake of reductionism, what should be removed to make room for them? Is it necessary even possible to call Code Complete Code Complete if it doesn't have language features that even Delphi has like anonymous methods and generics? Also, what languages would be more appropriate than C++ to use for a majority of code examples?

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  • After how much line of code a function should be break down?

    - by Sumeet
    While working on existing code base, I usually come across procedures that contain Abusive use of IF and Switch statements. The procedures consist of overwhelming code, which I think require re-factoring badly. The situation gets worse when I identify that some of these are recursive as well. But this is always a matter of debate as the code is working fine and no one wants to wake up the dragon. But, everyone accepts it is very expensive code to manage. I am wondering if are any recommendations to determine if a particular Method is a culprit and needs a revisit/rewrite , so that it can broken down or polymophized in an effective manner. Are there any Metrics (like no. of lines in procedure) that can be used to identify such segment of code. The checklist or advice to convince everyone, will be great!

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  • Do you use to third party companies to review your company's code?

    - by CodeToGlory
    I am looking to get the following - Basic code review to make sure they follow the guidelines imposed. Security code analysis to make sure there are no loopholes. No performance bottlenecks by doing a load test etc. We have lot of code coming in from third parties and is becoming laborious to manage code reviews and hence looking to see if others employ such practices. I understand that it may be a concern for some and would raise the question "Well, who is going to make sure the agency is doing their job right?" But basically I am just looking for a third party who can hold all vendor code to the same standards.

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  • What is the right level of granularity for code commenting?

    - by Nick
    Commenting in code I believe is very important but recently I've been reviewing code that has left me wondering particular this one. //due to lack of confidence with web programming leaving this note in for now What is the right level of granularity for code commenting? EDIT: Obviously the above comment is shocking hence why I'm asking the question. I've recently noticed the inline comments in the code at my work place annoying. Instead of getting angry I want discovery the acceptable level of granularity for code commenting in the community.

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  • Is imposing the same code format for all developers a good idea?

    - by Stijn Geukens
    We are considering to impose a single standard code format in our project (auto format with save actions in Eclipse). The reason is that currently there is a big difference in the code formats used by several (10) developers which makes it harder for one developer to work on the code of another developer. The same Java file sometimes uses 3 different formats. So I believe the advantage is clear (readability = productivity) but would it be a good idea to impose this? And if not, why? UPDATE We all use Eclipse and everyone is aware of the plan. There already is a code format used by most but it is not enforced since some prefer to stick to their own code format. Because of the above reasons some would prefer to enforce it.

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  • which Project hosting service (Like google code, github) you will prefer to use? And Why?

    - by MobileDev123
    I am using to study (and at some point of time copy the desired module of) the code from these two sites (Google Code and Github). There is sourceforge too, I have some code, say some library that I want to share with the community, and I am to decide the hosting site. And before I decide I want to have opinions from this community. Which is your favorite Project hosting site or service? And why? There is one point where github can win over google code (may be I am wrong here), Github can let you forge whole project with a zip or tar file, but to do the same in google code we have to upload the zip file explicitly and put it in downloads.... Thanks

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  • How do I gather TeamCity code coverage reports from multiple projects into one report?

    - by Loofer
    We use the build in coverage application in TeamCity 6 (about to upgrade to 7.1) If we wish to see the code coverage (or other metrics) of a particular build it is fine as we can navigate to that build, but it would be great if we could pluck out a few interesting metrics from all/some of the current projects/build configurations and display them all together. For convenience I would expect the new display to be accessible from within TeamCity itself, however if there are solutions that require a separate solution we could look at them. Thanks

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  • Listing common SQL Code Smells.

    - by Phil Factor
    Once you’ve done a number of SQL Code-reviews, you’ll know those signs in the code that all might not be well. These ’Code Smells’ are coding styles that don’t directly cause a bug, but are indicators that all is not well with the code. . Kent Beck and Massimo Arnoldi seem to have coined the phrase in the "OnceAndOnlyOnce" page of www.C2.com, where Kent also said that code "wants to be simple". Bad Smells in Code was an essay by Kent Beck and Martin Fowler, published as Chapter 3 of the book ‘Refactoring: Improving the Design of Existing Code’ (ISBN 978-0201485677) Although there are generic code-smells, SQL has its own particular coding habits that will alert the programmer to the need to re-factor what has been written. See Exploring Smelly Code   and Code Deodorants for Code Smells by Nick Harrison for a grounding in Code Smells in C# I’ve always been tempted by the idea of automating a preliminary code-review for SQL. It would be so useful to trawl through code and pick up the various problems, much like the classic ‘Lint’ did for C, and how the Code Metrics plug-in for .NET Reflector by Jonathan 'Peli' de Halleux is used for finding Code Smells in .NET code. The problem is that few of the standard procedural code smells are relevant to SQL, and we need an agreed list of code smells. Merrilll Aldrich made a grand start last year in his blog Top 10 T-SQL Code Smells.However, I'd like to make a start by discovering if there is a general opinion amongst Database developers what the most important SQL Smells are. One can be a bit defensive about code smells. I will cheerfully write very long stored procedures, even though they are frowned on. I’ll use dynamic SQL occasionally. You can only use them as an aid for your own judgment and it is fine to ‘sign them off’ as being appropriate in particular circumstances. Also, whole classes of ‘code smells’ may be irrelevant for a particular database. The use of proprietary SQL, for example, is only a ‘code smell’ if there is a chance that the database will have to be ported to another RDBMS. The use of dynamic SQL is a risk only with certain security models. As the saying goes,  a CodeSmell is a hint of possible bad practice to a pragmatist, but a sure sign of bad practice to a purist. Plamen Ratchev’s wonderful article Ten Common SQL Programming Mistakes lists some of these ‘code smells’ along with out-and-out mistakes, but there are more. The use of nested transactions, for example, isn’t entirely incorrect, even though the database engine ignores all but the outermost: but it does flag up the possibility that the programmer thinks that nested transactions are supported. If anything requires some sort of general agreement, the definition of code smells is one. I’m therefore going to make this Blog ‘dynamic, in that, if anyone twitters a suggestion with a #SQLCodeSmells tag (or sends me a twitter) I’ll update the list here. If you add a comment to the blog with a suggestion of what should be added or removed, I’ll do my best to oblige. In other words, I’ll try to keep this blog up to date. The name against each 'smell' is the name of the person who Twittered me, commented about or who has written about the 'smell'. it does not imply that they were the first ever to think of the smell! Use of deprecated syntax such as *= (Dave Howard) Denormalisation that requires the shredding of the contents of columns. (Merrill Aldrich) Contrived interfaces Use of deprecated datatypes such as TEXT/NTEXT (Dave Howard) Datatype mis-matches in predicates that rely on implicit conversion.(Plamen Ratchev) Using Correlated subqueries instead of a join   (Dave_Levy/ Plamen Ratchev) The use of Hints in queries, especially NOLOCK (Dave Howard /Mike Reigler) Few or No comments. Use of functions in a WHERE clause. (Anil Das) Overuse of scalar UDFs (Dave Howard, Plamen Ratchev) Excessive ‘overloading’ of routines. The use of Exec xp_cmdShell (Merrill Aldrich) Excessive use of brackets. (Dave Levy) Lack of the use of a semicolon to terminate statements Use of non-SARGable functions on indexed columns in predicates (Plamen Ratchev) Duplicated code, or strikingly similar code. Misuse of SELECT * (Plamen Ratchev) Overuse of Cursors (Everyone. Special mention to Dave Levy & Adrian Hills) Overuse of CLR routines when not necessary (Sam Stange) Same column name in different tables with different datatypes. (Ian Stirk) Use of ‘broken’ functions such as ‘ISNUMERIC’ without additional checks. Excessive use of the WHILE loop (Merrill Aldrich) INSERT ... EXEC (Merrill Aldrich) The use of stored procedures where a view is sufficient (Merrill Aldrich) Not using two-part object names (Merrill Aldrich) Using INSERT INTO without specifying the columns and their order (Merrill Aldrich) Full outer joins even when they are not needed. (Plamen Ratchev) Huge stored procedures (hundreds/thousands of lines). Stored procedures that can produce different columns, or order of columns in their results, depending on the inputs. Code that is never used. Complex and nested conditionals WHILE (not done) loops without an error exit. Variable name same as the Datatype Vague identifiers. Storing complex data  or list in a character map, bitmap or XML field User procedures with sp_ prefix (Aaron Bertrand)Views that reference views that reference views that reference views (Aaron Bertrand) Inappropriate use of sql_variant (Neil Hambly) Errors with identity scope using SCOPE_IDENTITY @@IDENTITY or IDENT_CURRENT (Neil Hambly, Aaron Bertrand) Schemas that involve multiple dated copies of the same table instead of partitions (Matt Whitfield-Atlantis UK) Scalar UDFs that do data lookups (poor man's join) (Matt Whitfield-Atlantis UK) Code that allows SQL Injection (Mladen Prajdic) Tables without clustered indexes (Matt Whitfield-Atlantis UK) Use of "SELECT DISTINCT" to mask a join problem (Nick Harrison) Multiple stored procedures with nearly identical implementation. (Nick Harrison) Excessive column aliasing may point to a problem or it could be a mapping implementation. (Nick Harrison) Joining "too many" tables in a query. (Nick Harrison) Stored procedure returning more than one record set. (Nick Harrison) A NOT LIKE condition (Nick Harrison) excessive "OR" conditions. (Nick Harrison) User procedures with sp_ prefix (Aaron Bertrand) Views that reference views that reference views that reference views (Aaron Bertrand) sp_OACreate or anything related to it (Bill Fellows) Prefixing names with tbl_, vw_, fn_, and usp_ ('tibbling') (Jeremiah Peschka) Aliases that go a,b,c,d,e... (Dave Levy/Diane McNurlan) Overweight Queries (e.g. 4 inner joins, 8 left joins, 4 derived tables, 10 subqueries, 8 clustered GUIDs, 2 UDFs, 6 case statements = 1 query) (Robert L Davis) Order by 3,2 (Dave Levy) MultiStatement Table functions which are then filtered 'Sel * from Udf() where Udf.Col = Something' (Dave Ballantyne) running a SQL 2008 system in SQL 2000 compatibility mode(John Stafford)

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