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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• College Ratings via the Federal Government

  - by user9147039

  A few weeks back you might remember news about a higher education rating system proposal from the Obama administration. As I've discussed previously, political and stakeholder pressures to improve outcomes and increase transparency are stronger than ever before. The executive branch proposal is intended to make progress in this area. Quoting from the proposal itself, "The ratings will be based upon such measures as: Access, such as percentage of students receiving Pell grants; Affordability, such as average tuition, scholarships, and loan debt; and Outcomes, such as graduation and transfer rates, graduate earnings, and advanced degrees of college graduates.” This is going to be quite complex, to say the least. Most notably, higher ed is not monolithic. From community and other 2-year colleges, to small private 4-year, to professional schools, to large public research institutions…the many walks of higher ed life are, well, many. Designing a ratings system that doesn't wind up with lots of unintended consequences and collateral damage will be difficult. At best you would end up potentially tarnishing the reputation of certain institutions that were actually performing well against the metrics and outcome measures that make sense in their "context" of education. At worst you could spend a lot of time and resources designing a system that would lose credibility with its "customers". A lot of institutions I work with already have in place systems like the one described above. They are tracking completion rates, completion timeframes, transfers to other institutions, job placement, and salary information. As I talk to these institutions there are several constants worth noting: • Deciding on which metrics to measure is complicated. While employment and salary data are relatively easy to track, qualitative measures are more difficult. How do you quantify the benefit to someone who studies in one field that may not compensate him or her as well as another field but that provides huge personal fulfillment and reward is a difficult measure to quantify? • The data is available but the systems to transform the data into actual information that can be used in meaningful ways are not. Too often in higher ed information is siloed. As such, much of the data that need to be a part of a comprehensive system sit in multiple organizations, oftentimes outside the reach of core IT. • Politics and culture are big barriers. One of the areas that my team and I spend a lot of time talking about with higher ed institutions all over the world is the imperative to optimize for student success. This, like the tracking of the students’ achievement after graduation, requires a level or organizational capacity that does not currently exist. The primary barrier is the culture of "data islands" in higher ed, and the need for leadership to drive out the divisions between departments, schools, colleges, etc. and institute academy-wide analytics and data stewardship initiatives that will enable student success. • Data quality is a very big issue. So many disparate systems exist (some on premise, some "in the cloud") that keep data about "persons" using different means to identify them. Establishing a single source of truth about an individual and his or her data is difficult without some type of data quality policy and tools. Good tools actually exist but are seldom leveraged. Don't misunderstand - I think it's a great idea to drive additional transparency and accountability into the system of higher education. And not just at home, but globally. Students and parents need access to key data to make informed, responsible choices. The tools exist to not only enable this kind of information to be shared but to capture the very metrics stakeholders care most about and in a way that makes sense in the context of a given institution's "place" in the overall higher ed panoply.

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• What do you need to know to be a world-class master software developer? [closed]

  - by glitch

  I wanted to bring up this question to you folks and see what you think, hopefully advise me on the matter: let's say you had 30 years of learning and practicing software development in front of you, how would you dedicate your time so that you'd get the biggest bang for your buck. What would you both learn and work on to be a world-class software developer that would make a large impact on the industry and leave behind a legacy? I think that most great developers end up being both broad generalists and specialists in one-two areas of interest. I'm thinking Bill Joy, John Carmack, Linus Torvalds, K&R and so on. I'm thinking that perhaps one approach would be to break things down by categories and establish a base minimum of "software development" greatness. I'm thinking: Operating Systems: completely internalize the core concepts of OS, perhaps gain a lot of familiarity with an OSS one such as Linux. Anything from memory management to device drivers has to be complete second nature. Programming Languages: this is one of those topics that imho has to be fully grokked even if it might take many years. I don't think there's quite anything like going through the process of developing your own compiler, understanding language design trade-offs and so on. Programming Language Pragmatics is one of my favorite books actually, I think you want to have that internalized back to back, and that's just the start. You could go significantly deeper, but I think it's time well spent, because it's such a crucial building block. As a subset of that, you want to really understand the different programming paradigms out there. Imperative, declarative, logic, functional and so on. Anything from assembly to LISP should be at the very least comfortable to write in. Contexts: I believe one should have experience working in different contexts to truly be able to appreciate the trade-offs that are being made every day. Embedded, web development, mobile development, UX development, distributed, cloud computing and so on. Hardware: I'm somewhat conflicted about this one. I think you want some understanding of computer architecture at a low level, but I feel like the concepts that will truly matter will be slightly higher level, such as CPU caching / memory hierarchy, ILP, and so on. Networking: we live in a completely network-dependent era. Having a good understanding of the OSI model, knowing how the Web works, how HTTP works and so on is pretty much a pre-requisite these days. Distributed systems: once again, everything's distributed these days, it's getting progressively harder to ignore this reality. Slightly related, perhaps add solid understanding of how browsers work to that, since the world seems to be moving so much to interfacing with everything through a browser. Tools: Have a really broad toolset that you're familiar with, one that continuously expands throughout the years. Communication: I think being a great writer, effective communicator and a phenomenal team player is pretty much a prerequisite for a lot of a software developer's greatness. It can't be overstated. Software engineering: understanding the process of building software, team dynamics, the requirements of the business-side, all the pitfalls. You want to deeply understand where what you're writing fits from the market perspective. The better you understand all of this, the more of your work will actually see the daylight. This is really just a starting list, I'm confident that there's a ton of other material that you need to master. As I mentioned, you most likely end up specializing in a bunch of these areas as you go along, but I was trying to come up with a baseline. Any thoughts, suggestions and words of wisdom from the grizzled veterans out there who would like to share their thoughts and experiences with this? I'd really love to know what you think!

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• Top 10 things I Learned this October

  - by rbewtra

  Last week, I attended the second largest IT conference. It was Gartner Symposium IT Expo held in Orlando, Florida. Earlier this month, I also had the opportunity to be part of the largest IT conference earlier in the month – Oracle Open World . Both were gatherings for senior IT professionals – CIOs, Senior IT  and Line of Business executives, and Developers. At both events, I learned a great deal about how companies are innovating and leveraging technology.  Here are my top 10 take-aways: #10.  Everyone is talking about Social, Mobile and Cloud  - Whether listening to Gartner discuss The Nexus of Forces or listening to Oracle’s Executive Vice President Hasan Rizvi deliver Oracle Fusion Middleware General Session  -- everyone is talking about Social, Mobile Cloud, and Information – Gartner, Oracle, our customers, partners, -- everyone.   #9. SOA is NOT dead, it is more important than ever before – it is an imperative!  #8. The big question around IT security is not “what will you do IF?” but “what will you do WHEN?” #7. General Colin Powell is an IT guy! Aside from having served as National Security Advisor, Chairman of the Joint Chiefs of Staff and as the U.S. Secretary of State. Gen Colin Powell was an inspirational speaker at the Gartner Symposium and it was clear he understands IT and the powerful impact it has on our society and our youth today. #6. Change will happen, we need to plan for it! #5. When everything is connected and just works, we have harnessed the power of technology. Middleware is at the heart of social, mobile and cloud. #4. Innovation is happening everywhere! Attending both IT events I was able to hear from companies of all sizes and across industries – including Tesco, Nike, Electronic Arts, Nintendo, International Speedway--  they all discussed how they are transforming their companies and their industries. #3. “One size fits all” strategy does not work instead it alienates IT and business. The PACE Layered Application Strategy is a framework that allows IT to have that Nexus of Forces conversation with the business. #2. To stay relevant, we need to hire the innovation workers, develop for that innovation layer. #1. My smartphone is the most valuable tool I own! Everyday with it, I am able to communicate via phone, email, text with family, friends, colleagues. I am able to look up directions to my hotel, make reservations at restaurants, view my calendar, take pictures, record messages, check in for flights and so much more…. I can never leave home without it. Look forward to catching up again soon! Additional Information Product Information on Oracle.com: Oracle Fusion Middleware Follow us on Twitter and Facebook Subscribe to our regular Fusion Middleware Newsletter

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• Top-Rated JavaScript Blogs

  - by Andreas Grech

  I am currently trying to find some blogs that talk (almost solely) on the JavaScript Language, and this is due to the fact that most of the time, bloggers with real life experience at work or at home development can explain more clearly and concisely certain quirks and hidden features than most 'Official Language Specifications' Below find a list of blogs that are JavaScript based (will update the list as more answers flow in): DHTML Kitchen, by Garrett Smith Robert's Talk, by Robert Nyman EJohn, by John Resig (of jQuery) Crockford's JavaScript Page, by Douglas Crockford Dean.edwards.name, by Dean Edwards Ajaxian, by various (@Martin) The JavaScript Weblog, by various SitePoint's JavaScript and CSS Page, by various AjaxBlog, by various Eric Lippert's Blog, by Eric Lippert (talks about JScript and JScript.Net) Web Bug Track, by various (@scunliffe) The Strange Zen Of JavaScript , by Scott Andrew Alex Russell (of Dojo) (@Eran Galperin) Ariel Flesler (@Eran Galperin) Nihilogic, by Jacob Seidelin (@llimllib) Peter's Blog, by Peter Michaux (@Borgar) Flagrant Badassery, by Steve Levithan (@Borgar) ./with Imagination, by Dustin Diaz (@Borgar) HedgerWow (@Borgar) Dreaming in Javascript, by Nosredna spudly.shuoink.com, by Stephen Sorensen Yahoo! User Interface Blog, by various (@Borgar) remy sharp's b:log, by Remy Sharp (@Borgar) JScript Blog, by the JScript Team (@Borgar) Dmitry Baranovskiy’s Web Log, by Dmitry Baranovskiy James Padolsey's Blog (@Kenny Eliasson) Perfection Kills; Exploring JavaScript by example, by Juriy Zaytsev DailyJS (@Ric) NCZOnline (@Kenny Eliasson), by Nicholas C. Zakas Which top-rated blogs am I currently missing from the above list, that you think should be imperative to any JavaScript developer to read (and follow) concurrently?

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• Scheme Infix to Postfix

  - by Cody

  Let me establish that this is part of a class assignment, so I'm definitely not looking for a complete code answer. Essentially we need to write a converter in Scheme that takes a list representing a mathematical equation in infix format and then output a list with the equation in postfix format. We've been provided with the algorithm to do so, simple enough. The issue is that there is a restriction against using any of the available imperative language features. I can't figure out how to do this in a purely functional manner. This is our fist introduction to functional programming in my program. I know I'm going to be using recursion to iterate over the list of items in the infix expression like such. (define (itp ifExpr) ( ; do some processing using cond statement (itp (cdr ifExpr)) )) I have all of the processing implemented (at least as best I can without knowing how to do the rest) but the algorithm I'm using to implement this requires that operators be pushed onto a stack and used later. My question is how do I implement a stack in this function that is available to all of the recursive calls as well?

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• Functional way to get a matrix from text

  - by Elazar Leibovich

  I'm trying to solve some Google Code Jam problems, where an input matrix is typically given in this form: 2 3 #matrix dimensions 1 2 3 4 5 6 7 8 9 # all 3 elements in the first row 2 3 4 5 6 7 8 9 0 # each element is composed of three integers where each element of the matrix is composed of, say, three integers. So this example should be converted to #!scala Array( Array(A(1,2,3),A(4,5,6),A(7,8,9), Array(A(2,3,4),A(5,6,7),A(8,9,0), ) An imperative solution would be of the form #!python input = """2 3 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 0 """ lines = input.split('\n') print lines[0] m,n = (int(x) for x in lines[0].split()) array = [] row = [] A = [] for line in lines[1:]: for elt in line.split(): A.append(elt) if len(A)== 3: row.append(A) A = [] array.append(row) row = [] from pprint import pprint pprint(array) A functional solution I've thought of is #!scala def splitList[A](l:List[A],i:Int):List[List[A]] = { if (l.isEmpty) return List[List[A]]() val (head,tail) = l.splitAt(i) return head :: splitList(tail,i) } def readMatrix(src:Iterator[String]):Array[Array[TrafficLight]] = { val Array(x,y) = src.next.split(" +").map(_.trim.toInt) val mat = src.take(x).toList.map(_.split(" "). map(_.trim.toInt)). map(a => splitList(a.toList,3). map(b => TrafficLight(b(0),b(1),b(2)) ).toArray ).toArray return mat } But I really feel it's the wrong way to go because: I'm using the functional List structure for each line, and then convert it to an array. The whole code seems much less efficeint I find it longer less elegant and much less readable than the python solution. It is harder to which of the map functions operates on what, as they all use the same semantics. What is the right functional way to do that?

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• ViewModel updates after Model server roundtrip

  - by Pavel Savara

  I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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• MVVM pattern: ViewModel updates after Model server roundtrip

  - by Pavel Savara

  I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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• How to perform undirected graph processing from SQL data

  - by recipriversexclusion

  I ran into the following problem in dynamically creating topics for our ActiveMQ system: I have a number of processes (M_1, ..., M_n), where n is not large, typically 5-10. Some of the processes will listen to the output of others, through a message queue; these edges are specified in an XML file, e.g. <link from="M1" to="M3"</link> <link from="M2" to="M4"</link> <link from="M3" to="M4"</link> etc. The edges are sparse, so there won't be many of them. I will parse this XML and store this information in an SQL DB, one table for nodes and another for edges. Now, I need to dynamically create strings of the form M1.exe --output_topic=T1 M2.exe --output_topic=T2 M3.exe --input_topic=T1 --output_topic=T3 M4.exe --input_topic=T2 --input_topic=T3 where the tags are sequentially generated. What is the best way to go about querying SQL to obtain these relationships? Are there any tools or other tutorials you can point me to? I've never done graps with SQL. Using SQL is imperative, because we use it for other stuff, too. Thanks!

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• Truly declarative language?

  - by gjvdkamp

  Hi all, Does anyone know of a truly declarative language? The behaviour I'm looking for is kind of what Excel does, where I can define variables and formulas, and have the formula's result change when the input changes (without having set the answer again myself) The behaviour I'm looking for is best shown with this pseudo code: X = 10 // define and assign two variables Y = 20; Z = X + Y // declare a formula that uses these two variables X = 50 // change one of the input variables ?Z // asking for Z should now give 70 (50 + 20) I've tried this in a lot of languages like F#, python, matlab etc, but every time i try this they come up with 30 instead of 70. Wich is correct from an imperative point of view, but i'm looking for a more declerative behaviour if you know what i mean. And this is just a very simple calculation. When things get more difficult it should handle stuff like recursion and memoization automagically. The code below would obviously work in C# but it's just so much code for the job, i'm looking for something a bit more to the point without all that 'technical noise' class BlaBla{ public int X {get;set;} // this used to be even worse before 3.0 public int Y {get;set;} public int Z {get{return X + Y;}} } static void main(){ BlaBla bla = new BlaBla(); bla.X = 10; bla.Y = 20; // can't define anything here bla.X = 50; // bit pointless here but I'll do it anyway. Console.Writeline(bla.Z);// 70, hurray! } This just seems like so much code, curly braces and semicolons that add nothing. Is there a language/ application (apart from Exel) that does this? Maybe I'm no doing it right in the mentioned langauges, or I've completely missed an app that does just this. I prototyped a language/ application that does this (along with some other stuff) and am thinking of productizing it. I just can't believe it's not there yet. Don't want to waste my time. Thanks in advance, Gert-Jan

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• C# how to calculate hashcode from an object reference.

  - by Wayne

  Folks, here's a thorny problem for you! A part of the TickZoom system must collect instances of every type of object into a Dictionary< type. It is imperative that their equality and hash code be based on the instance of the object which means reference equality instead of value equality. The challenge is that some of the objects in the system have overridden Equals() and GetHashCode() for use as value equality and their internal values will change over time. That means that their Equals and GetHashCode are useless. How to solve this generically rather than intrusively? So far, We created a struct to wrap each object called ObjectHandle for hashing into the Dictionary. As you see below we implemented Equals() but the problem of how to calculate a hash code remains. public struct ObjectHandle : IEquatable<ObjectHandle>{ public object Object; public bool Equals(ObjectHandle other) { return object.ReferenceEquals(this.Object,other.Object); } } See? There is the method object.ReferenceEquals() which will compare reference equality without regard for any overridden Equals() implementation in the object. Now, how to calculate a matching GetHashCode() by only considering the reference without concern for any overridden GetHashCode() method? Ahh, I hope this give you an interesting puzzle. We're stuck over here. Sincerely, Wayne

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• What's the idiomatic way of inheriting data access functionality as well as object properties?

  - by Knut Arne Vedaa

  Suppose the following (slightly pseudo-code for brevity): class Basic { String foo; } class SomeExtension extends Basic { String bar; } class OtherExtension extends Basic { String baz; } class BasicService { Basic getBasic() { } } class SomeExtensionService extends BasicService { SomeExtension getSomeExtension() { } } class OtherExtensionService extends BasicService { OtherExtension getOtherExtension() { } } What would be the most idiomatic, elegant way to implement the get-() service methods with the most possible code reuse? Obviously you could do it like this: class BasicService { Basic getBasic() { Basic basic = new Basic(); basic.setFoo("some kind of foo"); return basic; } } class SomeExtensionService { SomeExtension getSomeExtension() { SomeExtension someExtension = new SomeExtension; Basic basic = getBasic(); someExtension.setFoo(basic.getFoo()); someExtension.setBar("some kind of bar"); return someExtension; } } But this would be ugly if Basic has a lot of properties, and also you only need one object, as SomeExtension already inherits Basic. However, BasicService can obviously not return a SomeExtension object. You could also have the get methods not create the object themselves, but create it at the outermost level and pass it to the method for filling in the properties, but I find that too imperative. (Please let me know if the question is confusingly formulated.)

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• SQL problem - select accross multiple tables (user groups)

  - by morpheous

  I have a db schema which looks something like this: create table user (id int, name varchar(32)); create table group (id int, name varchar(32)); create table group_member (foobar_id int, user_id int, flag int); I want to write a query that allows me to so the following: Given a valid user id (UID), fetch the ids of all users that are in the same group as the specified user id (UID) AND have group_member.flag=3. Rather than just have the SQL. I want to learn how to think like a Db programmer. As a coder, SQL is my weakest link (since I am far more comfortable with imperative languages than declarative ones) - but I want to change that. Anyway here are the steps I have identified as necessary to break down the task. I would be grateful if some SQL guru can demonstrate the simple SQL statements - i.e. atomic SQL statements, one for each of the identified subtasks below, and then finally, how I can combine those statements to make the ONE statement that implements the required functionality. Here goes (assume specified user_id [UID] = 1): //Subtask #1. Fetch list of all groups of which I am a member Select group.id from user inner join group_member where user.id=group_member.user_id and user.id=1 //Subtask #2 Fetch a list of all members who are members of the groups I am a member of (i.e. groups in subtask #1) Not sure about this ... select user.id from user, group_member gm1, group_member gm2, ... [Stuck] //Subtask #3 Get list of users that satisfy criteria group_member.flag=3 Select user.id from user inner join group_member where user.id=group_member.user_id and user.id=1 and group_member.flag=3 Once I have the SQL for subtask2, I'd then like to see how the complete SQL statement is built from these subtasks (you dont have to use the SQL in the subtask, it just a way of explaining the steps involved - also, my SQL may be incorrect/inefficient, if so, please feel free to correct it, and point out what was wrong with it). Thanks

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• OCaml delimiters and scopes

  - by Jack

  Hello! I'm learning OCaml and although I have years of experience with imperative programming languages (C, C++, Java) I'm getting some problems with delimiters between declarations or expressions in OCaml syntax. Basically I understood that I have to use ; to concatenate expressions and the value returned by the sequence will be the one of last expression used, so for example if I have exp1; exp2; exp3 it will be considered as an expression that returns the value of exp3. Starting from this I could use let t = something in exp1; exp2; exp3 and it should be ok, right? When am I supposed to use the double semicol ;;? What does it exactly mean? Are there other delimiters that I must use to avoid syntax errors? I'll give you an example: let rec satisfy dtmc state pformula = match (state, pformula) with (state, `Next sformula) -> let s = satisfy_each dtmc sformula and adder a state = let p = 0.; for i = 0 to dtmc.matrix.rows do p <- p +. get dtmc.matrix i state.index done; a +. p in List.fold_left adder 0. s | _ -> [] It gives me syntax error on | but I don't get why.. what am I missing? This is a problem that occurs often and I have to try many different solutions until it suddently works :/ A side question: declaring with let instead that let .. in will define a var binding that lasts whenever after it has been defined? What I basically ask is: what are the delimiters I have to use and when I have to use them. In addition are there differences I should consider while using the interpreter ocaml instead that the compiler ocamlc? Thanks in advance!

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• What's the *right* way to handle a POST in FP?

  - by Malvolio

  I'm just getting started with FP and I'm using Scala, which may not be the best way, since I can always fall back to an imperative style if the going gets tough. I'd just rather not. I've got a very specific question that points to a broader lacuna in my understanding of FP. When a web application is processing a GET request, the user wants information that already exists on the web-site. The application only has to process and format the data in some way. The FB way is clear. When a web application is processing a POST request, the user wants change the information held on the site. True, the information is not typically held in application variables, it's in a database or a flat-file, but still, I get the feeling I'm not grokking FP properly. Is there a pattern for handling updates to static data in an FP language? My vague picture of this is that the application is handed the request and the then-current site state. The application does its thing and returns the new site-state. If the current site-state hasn't changed since the application started, the new state becomes the current state and the reply is sent back to the browser (this is my dim image of Clojure's style); if the current state has been changed (by another thread, well, something else happens ...

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• What’s Your Tax Strategy? Automate the Tax Transfer Pricing Process!

  - by tobyehatch

  Does your business operate in multiple countries? Well, whether you like it or not, many local and international tax authorities inspect your tax strategy.  Legal, effective tax planning is perceived as a “moral” issue. CEOs are being asked to testify on their process of tax transfer pricing between multinational legal entities.  Marc Seewald, Senior Director of Product Management for EPM Applications specializing in all tax subjects and Product Manager for Oracle Hyperion Tax Provisioning, and Bart Stoehr, Senior Director of Product Strategy for Oracle Hyperion Profitability and Cost Management joined me for a discussion/podcast on this interesting subject.  So what exactly is “tax transfer pricing”? Marc defined it this way. “Tax transfer pricing is a profit allocation methodology required to be used by multinational corporations. Specifically, the ultimate goal of the transfer pricing is to ensure that the global multinational pays their fair share of income tax in each of their local markets. Specifically, it prevents companies from unfairly moving profit from ‘high tax’ countries to ‘low tax’ countries.” According to Marc, in today’s global economy, profitability can be significantly impacted by goods and services exchanged between the related divisions within a single multinational company.  To ensure that these cost allocations are done fairly, there are rules that govern the process. These rules ensure that intercompany allocations fairly represent the actual nature of the businesses activity- as if two divisions were unrelated - and provide a clear audit trail of how the costs have been allocated to prove that allocations fall within reasonable ranges.  What are the repercussions of improper tax transfer pricing? How important is it? Tax transfer pricing allocations can materially impact the amount of overall corporate income taxes paid by a company worldwide, in some cases by hundreds of millions of dollars!  Since so much tax revenue is at stake, revenue agencies like the IRS, and international regulatory bodies like the Organization for Economic Cooperation and Development (OECD) are pushing to reform and clarify reporting for tax transfer pricing. Most recently the OECD announced an “Action Plan for Base Erosion and Profit Shifting”. As Marc explained, the times are changing and companies need to be responsive to this issue. “It feels like every other week there is another company being accused of avoiding taxes,” said Marc. Most recently, Caterpillar was accused of avoiding billions of dollars in taxes. In the last couple of years, Apple, GE, Ikea, and Starbucks, have all been accused of tax avoidance. It’s imperative that companies like these have a clear and auditable tax transfer process that enables them to justify tax transfer pricing allocations and avoid steep penalties and bad publicity. Transparency and efficiency are what is needed when it comes to the tax transfer pricing process. Bart explained that tax transfer pricing is driving a deeper inspection of profit recognition specifically focused on the tax element of profit.  However, allocations needed to support tax profitability are nearly identical in process to allocations taking place in other parts of the finance organization. For example, the methods and processes necessary to arrive at tax profitability by legal entity are no different than those used to arrive at fully loaded profitability for a product line. In fact, there is a great opportunity for alignment across these two different functions.So it seems that tax transfer pricing should be reflected in profitability in general. Bart agreed and told us more about some of the critical sub-processes of an overall tax transfer pricing process within the Oracle solution for tax transfer pricing.  “First, there is a ton of data preparation, enrichment and pre-allocation data analysis that is managed in the Oracle Hyperion solution. This serves as the “data staging” to the next, critical sub-processes.  From here, we leverage the Oracle EPM platform’s ability to re-use dimensions and legal entity driver data and financial data with Oracle Hyperion Profitability and Cost Management (HPCM).  Within HPCM, we manage the driver data, define the legal entity to legal entity allocation rules (like cost plus), and have the option to test out multiple, simultaneous tax transfer pricing what-if scenarios.  Once processed, a tax expert can evaluate the effectiveness of any one scenario result versus another via a variance analysis configured with HPCM’s pre-packaged reporting capability known as Oracle Hyperion SmartView for Office.”   Further, Bart explained that the ability to visibly demonstrate how a cost or revenue has been allocated is really helpful and auditable.  “HPCM’s Traceability Maps are that visual representation of all allocation flows that have been executed and is the tax transfer analyst’s best friend in maintaining clear documentation for tax transfer pricing audits. Simply click and drill as you inspect the chain of allocation definitions and results. Once final, the post-allocated tax data can be compared to the GL to create invoices and journal entries for posting to your GL system of choice.  Of course, there is a framework for overall governance of the journal entries, allocation percentages, and reporting to include necessary approvals.” Lastly, Marc explained that the key value in using the Oracle Hyperion solution for tax transfer pricing is that it keeps everything in alignment in one single place. Specifically, Oracle Hyperion effectively becomes the single book of record for the GAAP, management, and the tax set of books. There are many benefits to having one source of the truth. These include EFFICIENCY, CONTROLS and TRANSPARENCY.So, what’s your tax strategy? Why not automate the tax transfer pricing process!To listen to the entire podcast, click here.To learn more about Oracle Hyperion Profitability and Cost Management (HPCM), click here.

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• Do You Develop Your PL/SQL Directly in the Database?

  - by thatjeffsmith

  I know this sounds like a REALLY weird question for many of you. Let me make one thing clear right away though, I am NOT talking about creating and replacing PLSQL objects directly into a production environment. Do we really need to talk about developers in production again? No, what I am talking about is a developer doing their work from start to finish in a development database. These are generally available to a development team for building the next and greatest version of your databases and database applications. And of course you are using a third party source control system, right? Last week I was in Tampa, FL presenting at the monthly Suncoast Oracle User’s Group meeting. Had a wonderful time, great questions and back-and-forth. My favorite heckler was there, @oraclenered, AKA Chet Justice.  I was in the middle of talking about how it’s better to do your PLSQL work in the Procedure Editor when Chet pipes up - Don’t do it that way, that’s wrong Just press play to edit the PLSQL directly in the database Or something along those lines. I didn’t get what the heck he was talking about. I had been showing how the Procedure Editor gives you much better feedback and support when working with PLSQL. After a few back-and-forths I got to what Chet’s main objection was, and again I’m going to paraphrase: You should develop offline in your SQL worksheet. Don’t do anything in the database until it’s done. I didn’t understand. Were developers expected to be able to internalize and mentally model the PL/SQL engine, see where their errors were, etc in these offline scripts? No, please give Chet more credit than that. What is the ideal Oracle Development Environment? If I were back in the ‘real world’ of database development, I would do all of my development outside of the ‘dev’ instance. My development process looks a little something like this: Do I have a program that already does something like this – copy and paste Has some smart person already written something like this – copy and paste Start typing in the white-screen-of-panic and bungle along until I get something that half-works Tweek, debug, test until I have fooled my subconscious into thinking that it’s ‘good’ As you might understand, I don’t want my co-workers to see the evolution of my code. It would seriously freak them out and I probably wouldn’t have a job anymore (don’t remind me that I already worked myself out of development.) So here’s what I like to do: Run a Local Instance of Oracle on my Machine and Develop My Code Privately I take a copy of development – that’s what source control is for afterall – and run it where no one else can see it. I now get to be my own DBA. If I need a trace – no problem. If I want to run an ASH report, no worries. If I need to create a directory or run some DataPump jobs, that’s all on me. Now when I get my code ‘up to snuff,’ then I will check it into source control and compile it into the official development instance. So my teammates suddenly go from seeing no program, to a mostly complete program. Is this right? If not, it doesn’t seem wrong to me. And after talking to Chet in the car on the way to the local cigar bar, it seems that he’s of the same opinion. So what’s so wrong with coding directly into a development instance? I think ‘wrong’ is a bit strong here. But there are a few pitfalls that you might want to look out for. A few come to mind – and I’m sure Chet could add many more as my memory fails me at the moment. But here goes: Development instance isn’t properly backed up – would hate to lose that work Development is wiped once a week and copied over from Prod – don’t laugh Someone clobbers your code You accidentally on purpose clobber someone else’s code The more developers you have in a single fish pond, the greater chance something ‘bad’ will happen This Isn’t One of Those Posts Where I Tell You What You Should Be Doing I realize many shops won’t be open to allowing developers to stage their own local copies of Oracle. But I would at least be aware that many of your developers are probably doing this anyway – with or without your tacit approval. SQL Developer can do local file tracking, but you should be using Source Control too! I will say that I think it’s imperative that you control your source code outside the database, even if your development team is comprised of a single developer. Store your source code in a file, and control that file in something like Subversion. You would be shocked at the number of teams that do not use a source control system. I know I continue to be shocked no matter how many times I meet another team running by the seat-of-their-pants. I’d love to hear how your development process works. And of course I want to know how SQL Developer and the rest of our tools can better support your processes. And one last thing, if you want a fun and interactive presentation experience, be sure to have Chet in the room

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• Puppet: Making Windows Awesome Since 2011

  - by Robz / Fervent Coder

  Originally posted on: http://geekswithblogs.net/robz/archive/2014/08/07/puppet-making-windows-awesome-since-2011.aspxPuppet was one of the first configuration management (CM) tools to support Windows, way back in 2011. It has the heaviest investment on Windows infrastructure with 1/3 of the platform client development staff being Windows folks.  It appears that Microsoft believed an end state configuration tool like Puppet was the way forward, so much so that they cloned Puppet’s DSL (domain-specific language) in many ways and are calling it PowerShell DSC. Puppet Labs is pushing the envelope on Windows. Here are several things to note: Puppet x64 Ruby support for Windows coming in v3.7.0. An awesome ACL module (with order, SIDs and very granular control of permissions it is best of any CM). A wealth of modules that work with Windows on the Forge (and more on GitHub). Documentation solely for Windows folks - https://docs.puppetlabs.com/windows. Some of the common learning points with Puppet on Windows user are noted in this recent blog post. Microsoft OpenTech supports Puppet. Azure has the ability to deploy a Puppet Master (http://puppetlabs.com/solutions/microsoft). At Microsoft //Build 2014 in the Day 2 Keynote Puppet Labs CEO Luke Kanies co-presented with Mark Russonivich (http://channel9.msdn.com/Events/Build/2014/KEY02  fast forward to 19:30)! Puppet has a Visual Studio Plugin! It can be overwhelming learning a new tool like Puppet at first, but Puppet Labs has some resources to help you on that path. Take a look at the Learning VM, which has a quest-based learning tool. For real-time questions, feel free to drop onto #puppet on freenode.net (yes, some folks still use IRC) with questions, and #puppet-dev with thoughts/feedback on the language itself. You can subscribe to puppet-users / puppet-dev mailing lists. There is also ask.puppetlabs.com for questions and Server Fault if you want to go to a Stack Exchange site. There are books written on learning Puppet. There are even Puppet User Groups (PUGs) and other community resources! Puppet does take some time to learn, but with anything you need to learn, you need to weigh the benefits versus the ramp up time. I learned NHibernate once, it had a very high ramp time back then but was the only game on the street. Puppet’s ramp up time is considerably less than that. The advantage is that you are learning a DSL, and it can apply to multiple platforms (Linux, Windows, OS X, etc.) with the same Puppet resource constructs. As you learn Puppet you may wonder why it has a DSL instead of just leveraging the language of Ruby (or maybe this is one of those things that keeps you up wondering at night). I like the DSL over a small layer on top of Ruby. It allows the Puppet language to be portable and go more places. It makes you think about the end state of what you want to achieve in a declarative sense instead of in an imperative sense. You may also find that right now Puppet doesn’t run manifests (scripts) in order of the way resources are specified. This is the number one learning point for most folks. As a long time consternation of some folks about Puppet, manifest ordering was not possible in the past. In fact it might be why some other CMs exist! As of 3.3.0, Puppet can do manifest ordering, and it will be the default in Puppet 4. http://puppetlabs.com/blog/introducing-manifest-ordered-resources You may have caught earlier that I mentioned PowerShell DSC. But what about DSC? Shouldn’t that be what Windows users want to choose? Other CMs are integrating with DSC, will Puppet follow suit and integrate with DSC? The biggest concern that I have with DSC is it’s lack of visibility in fine-grained reporting of changes (which Puppet has). The other is that it is a very young Microsoft product (pre version 3, you know what they say :) ). I tried getting it working in December and ran into some issues. I’m hoping that newer releases are there that actually work, it does have some promising capabilities, it just doesn’t quite come up to the standard of something that should be used in production. In contrast Puppet is almost a ten year old language with an active community! It’s very stable, and when trusting your business to configuration management, you want something that has been around awhile and has been proven. Give DSC another couple of releases and you might see more folks integrating with it. That said there may be a future with DSC integration. Portability and fine-grained reporting of configuration changes are reasons to take a closer look at Puppet on Windows. Yes, Puppet on Windows is here to stay and it’s continually getting better folks.

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• Pace Layering Comes Alive

  - by Tanu Sood

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Rick Beers is Senior Director of Product Management for Oracle Fusion Middleware. Prior to joining Oracle, Rick held a variety of executive operational positions at Corning, Inc. and Bausch & Lomb. With a professional background that includes senior management positions in manufacturing, supply chain and information technology, Rick brings a unique set of experiences to cover the impact that technology can have on business models, processes and organizations. Rick hosts the IT Leaders Editorial on a monthly basis. By now, readers of this column are quite familiar with Oracle AppAdvantage, a unified framework of middleware technologies, infrastructure and applications utilizing a pace layered approach to enterprise systems platforms. 1. Standardize and Consolidate core Enterprise Applications by removing invasive customizations, costly workarounds and the complexity that multiple instances creates. 2. Move business specific processes and applications to the Differentiate Layer, thus creating greater business agility with process extensions and best of breed applications managed by cross- application process orchestration. 3. The Innovate Layer contains all the business capabilities required for engagement, collaboration and intuitive decision making. This is the layer where innovation will occur, as people engage one another in a secure yet open and informed way. 4. Simplify IT by minimizing complexity, improving performance and lowering cost with secure, reliable and managed systems across the entire Enterprise. But what hasn’t been discussed is the pace layered architecture that Oracle AppAdvantage adopts. What is it, what are its origins and why is it relevant to enterprise scale applications and technologies? It’s actually a fascinating tale that spans the past 20 years and a basic understanding of it provides a wonderful context to what is evolving as the future of enterprise systems platforms. It all begins in 1994 with a book by noted architect Stewart Brand, of ’Whole Earth Catalog’ fame. In his 1994 book How Buildings Learn, Brand popularized the term ‘Shearing Layers’, arguing that any building is actually a hierarchy of pieces, each of which inherently changes at different rates. In 1997 he produced a 6 part BBC Series adapted from the book, in which Part 6 focuses on Shearing Layers. In this segment Brand begins to introduce the concept of ‘pace’. Brand further refined this idea in his subsequent book, The Clock of the Long Now, which began to link the concept of Shearing Layers to computing and introduced the term ‘pace layering’, where he proposes that: “An imperative emerges: an adaptive [system] has to allow slippage between the differently-paced systems … otherwise the slow systems block the flow of the quick ones and the quick ones tear up the slow ones with their constant change. Embedding the systems together may look efficient at first but over time it is the opposite and destructive as well.” In 2000, IBM architects Ian Simmonds and David Ing published a paper entitled A Shearing Layers Approach to Information Systems Development, which applied the concept of Shearing Layers to systems design and development. It argued that at the time systems were still too rigid; that they constrained organizations by their inability to adapt to changes. The findings in the Conclusions section are particularly striking: “Our starting motivation was that enterprises need to become more adaptive, and that an aspect of doing that is having adaptable computer systems. The challenge is then to optimize information systems development for change (high maintenance) rather than stability (low maintenance). Our response is to make it explicit within software engineering the notion of shearing layers, and explore it as the principle that systems should be built to be adaptable in response to the qualitatively different rates of change to which they will be subjected. This allows us to separate functions that should legitimately change relatively slowly and at significant cost from that which should be changeable often, quickly and cheaply.” The problem at the time of course was that this vision of adaptable systems was simply not possible within the confines of 1st generation ERP, which were conceived, designed and developed for standardization and compliance. It wasn’t until the maturity of open, standards based integration, and the middleware innovation that followed, that pace layering became an achievable goal. And Oracle is leading the way. Oracle’s AppAdvantage framework makes pace layering come alive by taking a strategic vision 20 years in the making and transforming it to a reality. It allows enterprises to retain and even optimize their existing ERP systems, while wrapping around those ERP systems three layers of capabilities that inherently adapt as needed, at a pace that’s optimal for the enterprise.

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• J: Self-reference in bubble sort tacit implementation

  - by Yasir Arsanukaev

  Hello people! Since I'm beginner in J I've decided to solve a simple task using this language, in particular implementing the bubblesort algorithm. I know it's not idiomatically to solve such kind of problem in functional languages, because it's naturally solved using array element transposition in imperative languages like C, rather than constructing modified list in declarative languages. However this is the code I've written: (((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#)) ^: # Let's apply it to an array: (((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#)) ^: # 5 3 8 7 2 2 3 5 7 8 The thing that confuses me is $: referring to the statement within the outermost parentheses. Help says that: $: denotes the longest verb that contains it. The other book (~ 300 KiB) says: 3+4 7 5*20 100 Symbols like + and * for plus and times in the above phrases are called verbs and represent functions. You may have more than one verb in a J phrase, in which case it is constructed like a sentence in simple English by reading from left to right, that is 4+6%2 means 4 added to whatever follows, namely 6 divided by 2. Let's rewrite my code snippet omitting outermost ()s: ((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#) ^: # 5 3 8 7 2 2 3 5 7 8 Reuslts are the same. I couldn't explain myself why this works, why only ((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#) is treated as the longest verb for $: but not the whole expression ((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#) ^: # and not just (<./@(2&{.)), $:@((>./@(2&{.)),2&}.), because if ((<./@(2&{.)), $:@((>./@(2&{.)),2&}.)) ^: (1<#) is a verb, it should also form another verb after conjunction with #, i. e. one might treat the whole sentence (first snippet) as a verb. Probably there's some limit for the verb length limited by one conjunction. Look at the following code (from here): factorial =: (* factorial@<:) ^: (1&<) factorial 4 24 factorial within expression refers to the whole function, i. e. (* factorial@<:) ^: (1&<). Following this example I've used a function name instead of $:: bubblesort =: (((<./@(2&{.)), bubblesort@((>./@(2&{.)),2&}.)) ^: (1<#)) ^: # bubblesort 5 3 8 7 2 2 3 5 7 8 I expected bubblesort to refer to the whole function, but it doesn't seem true for me since the result is correct. Also I'd like to see other implementations if you have ones, even slightly refactored. Thanks.

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• SSH new connection begins to hang (not reject or terminate) after a day or so on Ubuntu 13.04 server

  - by kross

  Recently we upgraded the server from 12.04 LTS server to 13.04. All was well, including after a reboot. With all packages updated we began to see a strange issue, ssh works for a day or so (unclear on timing) then a later request for SSH hangs (cannot ctrl+c, nothing). It is up and serving webserver traffic etc. Port 22 is open (ips etc altered slightly for posting): nmap -T4 -A x.acme.com Starting Nmap 6.40 ( http://nmap.org ) at 2013-09-12 16:01 CDT Nmap scan report for x.acme.com (69.137.56.18) Host is up (0.026s latency). rDNS record for 69.137.56.18: c-69-137-56-18.hsd1.tn.provider.net Not shown: 998 filtered ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 6.1p1 Debian 4 (protocol 2.0) | ssh-hostkey: 1024 54:d3:e3:38:44:f4:20:a4:e7:42:49:d0:a7:f1:3e:21 (DSA) | 2048 dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 (RSA) |_256 45:69:10:79:5a:9f:0b:f0:66:15:39:87:b9:a1:37:f7 (ECDSA) 80/tcp open http Jetty 7.6.2.v20120308 | http-title: Log in as a Bamboo user - Atlassian Bamboo |_Requested resource was http://x.acme.com/userlogin!default.action;jsessionid=19v135zn8cl1tgso28fse4d50?os_destination=%2Fstart.action Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 12.89 seconds Here is the ssh -vvv: ssh -vvv x.acme.com OpenSSH_5.9p1, OpenSSL 0.9.8x 10 May 2012 debug1: Reading configuration data /Users/tfergeson/.ssh/config debug1: Reading configuration data /etc/ssh_config debug1: /etc/ssh_config line 20: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to x.acme.com [69.137.56.18] port 22. debug1: Connection established. debug3: Incorrect RSA1 identifier debug3: Could not load "/Users/tfergeson/.ssh/id_rsa" as a RSA1 public key debug1: identity file /Users/tfergeson/.ssh/id_rsa type 1 debug1: identity file /Users/tfergeson/.ssh/id_rsa-cert type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.1p1 Debian-4 debug1: match: OpenSSH_6.1p1 Debian-4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256 debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 130/256 debug2: bits set: 503/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: load_hostkeys: loading entries for host "69.137.56.18" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:6 debug3: load_hostkeys: loaded 1 keys debug1: Host 'x.acme.com' is known and matches the RSA host key. debug1: Found key in /Users/tfergeson/.ssh/known_hosts:10 debug2: bits set: 493/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /Users/tfergeson/.ssh/id_rsa (0x7ff189c1d7d0) debug2: key: /Users/tfergeson/.ssh/id_dsa (0x0) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /Users/tfergeson/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg ssh-rsa blen 277 debug2: input_userauth_pk_ok: fp 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug3: sign_and_send_pubkey: RSA 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug1: read PEM private key done: type RSA debug1: Authentication succeeded (publickey). Authenticated to x.acme.com ([69.137.56.18]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting [email protected] debug1: Entering interactive session. debug2: callback start debug2: client_session2_setup: id 0 debug2: fd 3 setting TCP_NODELAY debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env ATLAS_OPTS debug3: Ignored env rvm_bin_path debug3: Ignored env TERM_PROGRAM debug3: Ignored env GEM_HOME debug3: Ignored env SHELL debug3: Ignored env TERM debug3: Ignored env CLICOLOR debug3: Ignored env IRBRC debug3: Ignored env TMPDIR debug3: Ignored env Apple_PubSub_Socket_Render debug3: Ignored env TERM_PROGRAM_VERSION debug3: Ignored env MY_RUBY_HOME debug3: Ignored env TERM_SESSION_ID debug3: Ignored env USER debug3: Ignored env COMMAND_MODE debug3: Ignored env rvm_path debug3: Ignored env COM_GOOGLE_CHROME_FRAMEWORK_SERVICE_PROCESS/USERS/tfergeson/LIBRARY/APPLICATION_SUPPORT/GOOGLE/CHROME_SOCKET debug3: Ignored env JPDA_ADDRESS debug3: Ignored env APDK_HOME debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env Apple_Ubiquity_Message debug3: Ignored env __CF_USER_TEXT_ENCODING debug3: Ignored env rvm_sticky_flag debug3: Ignored env MAVEN_OPTS debug3: Ignored env LSCOLORS debug3: Ignored env rvm_prefix debug3: Ignored env PATH debug3: Ignored env PWD debug3: Ignored env JAVA_HOME debug1: Sending env LANG = en_US.UTF-8 debug2: channel 0: request env confirm 0 debug3: Ignored env JPDA_TRANSPORT debug3: Ignored env rvm_version debug3: Ignored env M2_HOME debug3: Ignored env HOME debug3: Ignored env SHLVL debug3: Ignored env rvm_ruby_string debug3: Ignored env LOGNAME debug3: Ignored env M2_REPO debug3: Ignored env GEM_PATH debug3: Ignored env AWS_RDS_HOME debug3: Ignored env rvm_delete_flag debug3: Ignored env EC2_PRIVATE_KEY debug3: Ignored env RUBY_VERSION debug3: Ignored env SECURITYSESSIONID debug3: Ignored env EC2_CERT debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 I can hard reboot (only mac monitors at that location) and it will again be accessible. This now happens every single time. It is imperative that I get it sorted. The strange thing is that it behaves initially then starts to hang after several hours. I perused logs previously and nothing stood out. From the auth.log, I can see that it has allowed me in, but still I get nothing back on the client side: Sep 20 12:47:50 cbear sshd[25376]: Accepted publickey for tfergeson from 10.1.10.14 port 54631 ssh2 Sep 20 12:47:50 cbear sshd[25376]: pam_unix(sshd:session): session opened for user tfergeson by (uid=0) UPDATES: Still occurring even after setting UseDNS no and commenting out #session optional pam_mail.so standard noenv This does not appear to be a network/dns related issue, as all services running on the machine are as responsive and accessible as ever, with the exception of sshd. Any thoughts on where to start?

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• SQL SERVER – Core Concepts – Elasticity, Scalability and ACID Properties – Exploring NuoDB an Elastically Scalable Database System

  - by pinaldave

  I have been recently exploring Elasticity and Scalability attributes of databases. You can see that in my earlier blog posts about NuoDB where I wanted to look at Elasticity and Scalability concepts. The concepts are very interesting, and intriguing as well. I have discussed these concepts with my friend Joyti M and together we have come up with this interesting read. The goal of this article is to answer following simple questions What is Elasticity? What is Scalability? How ACID properties vary from NOSQL Concepts? What are the prevailing problems in the current database system architectures? Why is NuoDB  an innovative and welcome change in database paradigm? Elasticity This word’s original form is used in many different ways and honestly it does do a decent job in holding things together over the years as a person grows and contracts. Within the tech world, and specifically related to software systems (database, application servers), it has come to mean a few things - allow stretching of resources without reaching the breaking point (on demand). What are resources in this context? Resources are the usual suspects – RAM/CPU/IO/Bandwidth in the form of a container (a process or bunch of processes combined as modules). When it is about increasing resources the simplest idea which comes to mind is the addition of another container. Another container means adding a brand new physical node. When it is about adding a new node there are two questions which comes to mind. 1) Can we add another node to our software system? 2) If yes, does adding new node cause downtime for the system? Let us assume we have added new node, let us see what the new needs of the system are when a new node is added. Balancing incoming requests to multiple nodes Synchronization of a shared state across multiple nodes Identification of “downstate” and resolution action to bring it to “upstate” Well, adding a new node has its advantages as well. Here are few of the positive points Throughput can increase nearly horizontally across the node throughout the system Response times of application will increase as in-between layer interactions will be improved Now, Let us put the above concepts in the perspective of a Database. When we mention the term “running out of resources” or “application is bound to resources” the resources can be CPU, Memory or Bandwidth. The regular approach to “gain scalability” in the database is to look around for bottlenecks and increase the bottlenecked resource. When we have memory as a bottleneck we look at the data buffers, locks, query plans or indexes. After a point even this is not enough as there needs to be an efficient way of managing such large workload on a “single machine” across memory and CPU bound (right kind of scheduling)  workload. We next move on to either read/write separation of the workload or functionality-based sharing so that we still have control of the individual. But this requires lots of planning and change in client systems in terms of knowing where to go/update/read and for reporting applications to “aggregate the data” in an intelligent way. What we ideally need is an intelligent layer which allows us to do these things without us getting into managing, monitoring and distributing the workload. Scalability In the context of database/applications, scalability means three main things Ability to handle normal loads without pressure E.g. X users at the Y utilization of resources (CPU, Memory, Bandwidth) on the Z kind of hardware (4 processor, 32 GB machine with 15000 RPM SATA drives and 1 GHz Network switch) with T throughput Ability to scale up to expected peak load which is greater than normal load with acceptable response times Ability to provide acceptable response times across the system E.g. Response time in S milliseconds (or agreed upon unit of measure) – 90% of the time The Issue – Need of Scale In normal cases one can plan for the load testing to test out normal, peak, and stress scenarios to ensure specific hardware meets the needs. With help from Hardware and Software partners and best practices, bottlenecks can be identified and requisite resources added to the system. Unfortunately this vertical scale is expensive and difficult to achieve and most of the operational people need the ability to scale horizontally. This helps in getting better throughput as there are physical limits in terms of adding resources (Memory, CPU, Bandwidth and Storage) indefinitely. Today we have different options to achieve scalability: Read & Write Separation The idea here is to do actual writes to one store and configure slaves receiving the latest data with acceptable delays. Slaves can be used for balancing out reads. We can also explore functional separation or sharing as well. We can separate data operations by a specific identifier (e.g. region, year, month) and consolidate it for reporting purposes. For functional separation the major disadvantage is when schema changes or workload pattern changes. As the requirement grows one still needs to deal with scale need in manual ways by providing an abstraction in the middle tier code. Using NOSQL solutions The idea is to flatten out the structures in general to keep all values which are retrieved together at the same store and provide flexible schema. The issue with the stores is that they are compromising on mostly consistency (no ACID guarantees) and one has to use NON-SQL dialect to work with the store. The other major issue is about education with NOSQL solutions. Would one really want to make these compromises on the ability to connect and retrieve in simple SQL manner and learn other skill sets? Or for that matter give up on ACID guarantee and start dealing with consistency issues? Hybrid Deployment – Mac, Linux, Cloud, and Windows One of the challenges today that we see across On-premise vs Cloud infrastructure is a difference in abilities. Take for example SQL Azure – it is wonderful in its concepts of throttling (as it is shared deployment) of resources and ability to scale using federation. However, the same abilities are not available on premise. This is not a mistake, mind you – but a compromise of the sweet spot of workloads, customer requirements and operational SLAs which can be supported by the team. In today’s world it is imperative that databases are available across operating systems – which are a commodity and used by developers of all hues. An Ideal Database Ability List A system which allows a linear scale of the system (increase in throughput with reasonable response time) with the addition of resources A system which does not compromise on the ACID guarantees and require developers to learn new paradigms A system which does not force fit a new way interacting with database by learning Non-SQL dialect A system which does not force fit its mechanisms for providing availability across its various modules. Well NuoDB is the first database which has all of the above abilities and much more. In future articles I will cover my hands-on experience with it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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• Refactoring Part 1 : Intuitive Investments

  - by Wes McClure

  Fear, it’s what turns maintaining applications into a nightmare.  Technology moves on, teams move on, someone is left to operate the application, what was green is now perceived brown.  Eventually the business will evolve and changes will need to be made.  The approach to those changes often dictates the long term viability of the application.  Fear of change, lack of passion and a lack of interest in understanding the domain often leads to a paranoia to do anything that doesn’t involve duct tape and bailing twine.  Don’t get me wrong, those have a place in the short term viability of a project but they don’t have a place in the long term.  Add to it “us versus them” in regards to the original team and those that maintain it, internal politics and other factors and you have a recipe for disaster.  This results in code that quickly becomes unmanageable.  Even the most clever of designs will eventually become sub optimal and debt will amount that exponentially makes changes difficult.  This is where refactoring comes in, and it’s something I’m very passionate about.  Refactoring is about improving the process whereby we make change, it’s an exponential investment in the process of change. Without it we will incur exponential complexity that halts productivity. Investments, especially in the long term, require intuition and reflection.  How can we tackle new development effectively via evolving the original design and paying off debt that has been incurred? The longer we wait to ask and answer this question, the more it will cost us.  Small requests don’t warrant big changes, but realizing when changes now will pay off in the long term, and especially in the short term, is valuable. I have done my fair share of maintaining applications and continuously refactoring as needed, but recently I’ve begun work on a project that hasn’t had much debt, if any, paid down in years.  This is the first in a series of blog posts to try to capture the process which is largely driven by intuition of smaller refactorings from other projects. Signs that refactoring could help: Testability How can decreasing test time not pay dividends? One of the first things I found was that a very important piece often takes 30+ minutes to test.  I can only imagine how much time this has cost historically, but more importantly the time it might cost in the coming weeks: I estimate at least 10-20 hours per person!  This is simply unacceptable for almost any situation.  As it turns out, about 6 hours of working with this part of the application and I was able to cut the time down to under 30 seconds!  In less than the lost time of one week, I was able to fix the problem for all future weeks! If we can’t test fast then we can’t change fast, nor with confidence. Code is used by end users and it’s also used by developers, consider your own needs in terms of the code base.  Adding logic to enable/disable features during testing can help decouple parts of an application and lead to massive improvements.  What exactly is so wrong about test code in real code?  Often, these become features for operators and sometimes end users.  If you cannot run an integration test within a test runner in your IDE, it’s time to refactor. Readability Are variables named meaningfully via a ubiquitous language? Is the code segmented functionally or behaviorally so as to minimize the complexity of any one area? Are aspects properly segmented to avoid confusion (security, logging, transactions, translations, dependency management etc) Is the code declarative (what) or imperative (how)?  What matters, not how.  LINQ is a great abstraction of the what, not how, of collection manipulation.  The Reactive framework is a great example of the what, not how, of managing streams of data. Are constants abstracted and named, or are they just inline? Do people constantly bitch about the code/design? If the code is hard to understand, it will be hard to change with confidence.  It’s a large undertaking if the original designers didn’t pay much attention to readability and as such will never be done to “completion.”  Make sure not to go over board, instead use this as you change an application, not in lieu of changes (like with testability). Complexity Simplicity will never be achieved, it’s highly subjective.  That said, a lot of code can be significantly simplified, tidy it up as you go.  Refactoring will often converge upon a simplification step after enough time, keep an eye out for this. Understandability In the process of changing code, one often gains a better understanding of it.  Refactoring code is a good way to learn how it works.  However, it’s usually best in combination with other reasons, in effect killing two birds with one stone.  Often this is done when readability is poor, in which case understandability is usually poor as well.  In the large undertaking we are making with this legacy application, we will be replacing it.  Therefore, understanding all of its features is important and this refactoring technique will come in very handy. Unused code How can deleting things not help? This is a freebie in refactoring, it’s very easy to detect with modern tools, especially in statically typed languages.  We have VCS for a reason, if in doubt, delete it out (ok that was cheesy)! If you don’t know where to start when refactoring, this is an excellent starting point! Duplication Do not pray and sacrifice to the anti-duplication gods, there are excellent examples where consolidated code is a horrible idea, usually with divergent domains.  That said, mediocre developers live by copy/paste.  Other times features converge and aren’t combined.  Tools for finding similar code are great in the example of copy/paste problems.  Knowledge of the domain helps identify convergent concepts that often lead to convergent solutions and will give intuition for where to look for conceptual repetition. 80/20 and the Boy Scouts It’s often said that 80% of the time 20% of the application is used most.  These tend to be the parts that are changed.  There are also parts of the code where 80% of the time is spent changing 20% (probably for all the refactoring smells above).  I focus on these areas any time I make a change and follow the philosophy of the Boy Scout in cleaning up more than I messed up.  If I spend 2 hours changing an application, in the 20%, I’ll always spend at least 15 minutes cleaning it or nearby areas. This gives a huge productivity edge on developers that don’t. Ironically after a short period of time the 20% shrinks enough that we don’t have to spend 80% of our time there and can move on to other areas.   Refactoring is highly subjective, never attempt to refactor to completion!  Learn to be comfortable with leaving one part of the application in a better state than others.  It’s an evolution, not a revolution.  These are some simple areas to look into when making changes and can help get one started in the process.  I’ve often found that refactoring is a convergent process towards simplicity that sometimes spans a few hours but often can lead to massive simplifications over the timespan of weeks and months of regular development.

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