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  • What Design Pattern To Replace 'CurrentStep' Variable

    - by Rob P.
    Tried to search but didn't know how to phrase it. I've got some code that is essentially... Private CurMajorStep as Integer = 0 Private CurMinorStep as Integer = 0 Public Sub PerformNextStep() Select Case iMajorStep Case 0 ThingOne() Case 1 ThingTwo() Case 2 ThingThree() Case 3 ThingFour() Case 4 AnythingElse() Case 5 Finish() End Select End Sub And then, in some of those, the CurMinorStep keeps track of the current state of that particular 'step'. I hope that all makes sense. The code is messy and I know it's going to be problematic to maintain. Can someone point me to a clean OO pattern to handle this?

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  • try finally block around every Object.Create?

    - by max
    Hi, I have a general question about best practice in OO Delphi. Currently, I but a try finally block around everywhere, where I create an object, to free that object after usage (to avoid memory leaks). E.g.: aObject := TObject.Create; try aOBject.AProcedure(); ... finally aObject.Free; end; instead of: aObject := TObject.Create; aObject.AProcedure(); .. aObject.Free; To you think, it is good practice, or too much overhead? And what about the performance?

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  • .NET security mechanism to restrict access between two Types in the same Website project?

    - by jdk
    Question: Is there a mechanism in the .NET Framework to hide one custom Type from another without using separate projects/assemblies? I'm using C# with ASP.NET in a Website project (Note: Not a Web Application). Obviously there's not a way to enforce this restriction using language-specific OO keywords so I am looking for something else, for example: maybe a permission framework or code access mechanism, maybe something that uses meta data like Attributes. I'm unsure. I don't really care whether the solution actually hides classes from each other or just makes them inaccessible, etc. A runtime or design time answer will suffice. Looking for something easy to implement otherwise it's not worth the effort ... Background: I'm working in an ASP.NET Website project and the team has decided not to use separate project assemblies for different software layers. Therefore I'm looking for a way to have, for example, a DataAccess/ folder of which I disallow its classes to access other Types in the ASP.NET Website project.

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  • A toolset for self improvement and learning [closed]

    - by Sebastian
    Possible Duplicate: I’m having trouble learning I've been working as an IT consultant for 1½ years and I am very passionate about programming. Before that I studied MSc Software Engineering and had both a part time job as a developer for a big telecom company. During that time I also took extra courses and earned a SCJP certificate. I have been continuously reading a lot of books during the last 3½ years. Now to my problem. I want to continue learning and become a really, really good developer. Apart from my daytime job as a full time java developer I have taken university courses in, for me, new languages and paradigms. Most recently, android game development and then functional programming with Scala. I've read books, went to conferences and had a couple of presentations for internal training purposes in our local office. I want to have some advice from other people who have previously been in my situation or currently are. What are you guys doing to keep improving yourselves? Here is some things that I have found are working for me: Reading books I've mostly read books about best practices for programming, OO-design, refactoring, design patterns, tdd. Software craftmanship if you like. I keep a reading list and my current book is Apprenticeship patterns. Taking courses In my country we have a really good system for taking online distance courses. I have also taken one course at coursera.org and a highly recommend that platform. Ive looked at courses at oreilly.com, industriallogic, javaspecialists.eu and they seem to be okay. If someone gives these type of courses a really good review, I can probably convince my boss. Workshops that span over a couple of days would probably be harder, but Ive seen that uncle Bob will have one about refactoring and tdd in 6months not far from here.. :) Are their possibly some online learning platforms that I dont know about? Educational videos I've bought uncle bobs videos from cleancoders.com and I highly recommend them. The only thing I dont like is that they are quite expensive and that he talks about astronomy for ~10 minutes in every episode. Getting certified I had a lot of fun and learned a lot when I studied for the SCJP. I have also done some preparation for the microsoft equivalent but never went for it. I think it is a good when selling yourself as a newly graduated student and also will boost your knowledge if your are interested in it. Now I would like others to start sharing their experiences and possibly give me some advice! BR Sebastian

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  • Web application / Domain model integration using JSON capable DTOs [on hold]

    - by g-makulik
    I'm a bit confused about architectural choices for the web-applications/java/python world. For c/c++ world the available (open source) choices to implement web applications is pretty limited to zero, involving java or python the choices explode to a,- hard to sort out -, mess of available 'frameworks' and application approaches. I want to sort out a clean MVC model, where the M stands for a fully blown (POCO, POJO driven) domain model (according M.Fowler's EAA pattern) using a mature OO language (Java,C++) for implementation. The background is: I have a system with certain hardware components (that introduce system immanent active behavior) and a configuration database for system meta and HW-components configuration data (these are even usually self contained, since the HW-components are capable to persist their configuration data anyway). For realization of the configuration/status data exchange protocol with the HW-components we have chosen the Google Protobuf format, which works well for the directly wired communication with these components. This protocol is already used successfully with a Java based GUI application via TCP/IP connection to the main system controlling HW-component. This application has some drawbacks and design flaws for historical reasons. Now we want to develop an abstract model (domain model) for configuration and monitoring those HW-components, that represents a more use case oriented view to the overall system behavior. I have the feeling that a plain Java class model would fit best for this (c++ implementation seems to have too much implementation/integration overhead with viable language-bridge interfaces). Google Protobuf message definitions could still serve well to describe DTO objects used to interact with a domain model API. But integrating Google Protobuf messages client side for e.g. data binding in the current view doesn't seem to be a good choice. I'm thinking about some extra serialization features, e.g. for JSON based data exchange with the views/controllers. Most lightweight solutions seem to involve a python based presentation layer using JSON based data transfer (I'm at least not sure to be fully informed about this). Is there some lightweight (applicable for a limited ARM Linux platform) framework available, supporting such architecture to realize a web-application? UPDATE: According to my recent research and comments of colleagues I've noticed that using Java (and some JVM) might not be the preferable choice for integration with python on a limited linux system as we have (running on ARM9 with hard to discuss memory and MCU costs), but C/C++ modules would do well for this (since this forms the native interface to python extensions, doesn't it?). I can imagine to provide a domain model from an appropriate C/C++ API (though I still think it's more efforts and higher skill requirements for the involved developers to do with these languages). Still I'm searching for a good approach that supports such architecture. I'll appreciate any pointers!

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  • Duplication in parallel inheritance hierarchies

    - by flamingpenguin
    Using an OO language with static typing (like Java), what are good ways to represent the following model invariant without large amounts of duplication. I have two (actually multiple) flavours of the same structure. Each flavour requires its own (unique to that flavour data) on each of the objects within that structure as well as some shared data. But within each instance of the aggregation only objects of one (the same) flavour are allowed. FooContainer can contain FooSources and FooDestinations and associations between the "Foo" objects BarContainer can contain BarSources and BarDestinations and associations between the "Bar" objects interface Container() { List<? extends Source> sources(); List<? extends Destination> destinations(); List<? extends Associations> associations(); } interface FooContainer() extends Container { List<? extends FooSource> sources(); List<? extends FooDestination> destinations(); List<? extends FooAssociations> associations(); } interface BarContainer() extends Container { List<? extends BarSource> sources(); List<? extends BarDestination> destinations(); List<? extends BarAssociations> associations(); } interface Source { String getSourceDetail1(); } interface FooSource extends Source { String getSourceDetail2(); } interface BarSource extends Source { String getSourceDetail3(); } interface Destination { String getDestinationDetail1(); } interface FooDestination extends Destination { String getDestinationDetail2(); } interface BarDestination extends Destination { String getDestinationDetail3(); } interface Association { Source getSource(); Destination getDestination(); } interface FooAssociation extends Association { FooSource getSource(); FooDestination getDestination(); String getFooAssociationDetail(); } interface BarAssociation extends Association { BarSource getSource(); BarDestination getDestination(); String getBarAssociationDetail(); }

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  • Data Mining Resources

    - by Dejan Sarka
    There are many different types of analyses, each one with its own pros and cons. Relational reports have a predefined structure, and end users cannot change it. They are simple to use for end users. Reports can use real-time data and snapshots of data to show the state of a report at specific points in time. One of the drawbacks is that report authoring is limited to IT pros and advanced users. Any kind of dynamic restructuring is very limited. If real-time data is used for a report, the report has a negative impact on the performance of the source system. Processing of the reports might be slow because the data comes from relational database management systems, which are not optimized for reporting only. If you create a semantic model of your data, your end users can create ad-hoc report structures. However, the development is more complex because a developer is needed to create these semantic models. For OLAP, you typically use specialized database management systems. You get lightning speed of analyses. End users can use rich and thin clients to interactively change the structure of the report. Typically, they do it graphically. However, the development of an OLAP system is many times quite complex. It involves the preparation and maintenance of an enterprise data warehouse and OLAP cubes. In order to exploit the possibility of real-time restructuring of reports, the users must be both active and educated. The data is usually stale, as it is loaded into data warehouses and OLAP cubes with a scheduled process. With data mining, a structure is not selected in advance; it searches for the structure. As a result, data mining can give you the most valuable results because you can discover patterns you did not expect. A data mining model structure is limited only by the attributes that you use to train the model. One of the drawbacks is that a lot of knowledge is needed for a successful data mining project. End users have to understand the results. Subject matter experts and IT professionals need to understand business problem thoroughly. The development might be sometimes even more complex than the development of OLAP cubes. Each type of analysis has its own place in an enterprise system. SQL Server has tools for all kinds of analyses. However, data mining is the most advanced way of analyzing the data; this is the “I” in BI. In order to get the most out of it, you need to learn quite a lot. In this blog post, I am gathering together resources for learning, including forthcoming events. Books Multiple authors: SQL Server MVP Deep Dives – I wrote an introductory data mining chapter there. Erik Veerman, Teo Lachev and Dejan Sarka: MCTS Self-Paced Training Kit (Exam 70-448): Microsoft SQL Server 2008 - Business Intelligence Development and Maintenance – you can find a good overview of a complete BI solution, including data mining, in this book. Jamie MacLennan, ZhaoHui Tang, and Bogdan Crivat: Data Mining with Microsoft SQL Server 2008 – can’t miss this book if you want to mine your data with SQL Server tools. Michael Berry, Gordon Linoff: Mastering Data Mining: The Art and Science of Customer Relationship Management – data mining from both, business and technical perspective. Dorian Pyle: Data Preparation for Data Mining – an in-depth book about data preparation. Thomas and Ronald Wonnacott: Introductory Statistics – if you thought that you could get away without statistics, then you are not serious about data mining. Jiawei Han and Micheline Kamber: Data Mining Concepts and Techniques – in-depth explanation of the most popular data mining algorithms. Michael Berry and Gordon Linoff: Data Mining Techniques – another book that explains data mining algorithms, more fro a business perspective. Paolo Guidici: Applied Data Mining – very mathematical book, only if you enjoy statistics and mathematics in general. Forthcoming presentations I am presenting two data mining related sessions during the PASS Summit in Charlotte, NC: Wednesday, October 16th, 2013 - Fraud Detection: Notes from the Field – I am showing how to use data mining for a specific business problem. The presentation is based on real-life projects. Friday, October 18th: Excel 2013 Advanced Analytics – I am focusing on Excel Data Mining Add-ins, and how to use them together with Power Pivot and other add-ins. This is the most you can get out of Excel. Sinergija 2013, Belgrade, Serbia Tuesday, October 22nd: Excel 2013 Analytics to the Max – another presentation focusing on the most advanced analytics you can get in Excel. SQL Rally Amsterdam, Netherlands Thursday, November 7th: Advanced Analytics in Excel 2013 – and again I am presenting about data mining in Excel. Why three different titles for the same presentation? I don’t know, I guess I forgot the name I proposed every time right after I sent the proposal. Courses Data Mining with SQL Server 2012 – I wrote a 3-day course for SolidQ. If you are interested in this course, which I could also deliver in a shorter seminar way, you can contact your closes SolidQ subsidiary, or, of course, me directly on addresses [email protected] or [email protected]. This course could also complement the existing courseware portfolio of training providers, which are welcome to contact me as well. OK, now you know: no more excuses, start learning data mining, get the most out of your data

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  • Language Club

    - by Ben Griswold
    We started a language club at work this week.  Thus far, we have a collective interest in a number of languages: Python, Ruby, F#, Erlang, Objective-C, Scala, Clojure, Haskell and Go. There are more but these 9 received the most votes. During the first few meetings we are going to determine which language we should tackle first. To help make our selection, each member will provide a quick overview of their favored language by answering the following set of questions: Why are you interested in learning “your” language(s). (There’s lots of work, I’m an MS shill, It’s hip and  fun, etc) What type of language is it?  (OO, dynamic, functional, procedural, declarative, etc) What types of problems is your language best suited to solve?  (Algorithms over big data, rapid application development, modeling, merely academic, etc) Can you provide examples of where/how it is being used?  If it isn’t being used, why not?  (Erlang was invented at Ericsson to provide an extremely fault tolerant, concurrent system.) Quick history – Who created/sponsored the language?  When was it created?  Is it currently active? Does the language have hardware support (an attempt was made at one point to create processor instruction sets specific to Prolog), or can it run as an interpreted language inside another language (like Ruby in the JVM)? Are there facilities for programs written in this language to communicate with other languages?  How does this affect its utility? Does the language have a IDE tool support?  (Think Eclipse or Visual Studio) How well is the language supported in terms of books, community and documentation? What’s the number one things which differentiates the language from others?  (i.e. Why is it cool?) How is the language applicability to us as consultants?  What would the impact be of using the language in terms of cost, maintainability, personnel costs, etc.? What’s the number one things which differentiates the language from others?  (i.e. Why is it cool?) This should provide an decent introduction into nearly a dozen languages and give us enough context to decide which single language deserves our undivided attention for the weeks to come.  Stay tuned for the winner…

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  • So what are zones really?

    - by Bertrand Le Roy
    There is a (not so) particular kind of shape in Orchard: zones. Functionally, zones are places where other shapes can render. There are top-level zones, the ones defined on Layout, where widgets typically go, and there are local zones that can be defined anywhere. These local zones are what you target in placement.info. Creating a zone is easy because it really is just an empty shape. Most themes include a helper for it: Func<dynamic, dynamic> Zone = x => Display(x); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } With this helper, you can create a zone by simply writing: @Zone(Model.Header) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Let's deconstruct what's happening here with that weird Lambda. In the Layout template where we are working, the Model is the Layout shape itself, so Model.Header is really creating a new Header shape under Layout, or getting a reference to it if it already exists. The Zone function is then called on that object, which is equivalent to calling Display. In other words, you could have just written the following to get the exact same effect: @Display(Model.Header) The Zone helper function only exists to make the intent very explicit. Now here's something interesting: while this works in the Layout template, you can also make it work from any deeper-nested template and still create top-level zones. The difference is that wherever you are, Model is not the layout anymore so you need to access it in a different way: @Display(WorkContext.Layout.Header) This is still doing the exact same thing as above. One thing to know is that for top-level zones to be usable from the widget editing UI, you need one more thing, which is to specify it in the theme's manifest: Name: Contoso Author: The Orchard Team Description: A subtle and simple CMS themeVersion: 1.1 Tags: business, cms, modern, simple, subtle, product, service Website: http://www.orchardproject.net Zones: Header, Navigation, HomeFeaturedImage, HomeFeaturedHeadline, Messages, Content, ContentAside, TripelFirst, TripelSecond, TripelThird, Footer Local zones are just ordinary shapes like global zones, the only difference being that they are created on a deeper shape than layout. For example, in Content.cshtml, you can find our good old code fro creating a header zone: @Display(Model.Header) The difference here is that Model is no longer the Layout shape, so that zone will be local. The name of that local zone is what you specify in placement.info, for example: <Place Parts_Common_Metadata_Summary="Header:1"/> Now here's the really interesting part: zones do not even know that they are zones, and in fact any shape can be substituted. That means that if you want to add new shapes to the shape that some part has been emitting from its driver for example, you can absolutely do that. And because zones are so barebones as shapes go, they can be created the first time they are accessed. This is what enables us to add shapes into a zone before the code that you would think creates it has even run. For example, in the Layout.cshtml template in TheThemeMachine, the BadgeOfHonor shape is being injected into the Footer zone on line 47, even though that zone will really be "created" on line 168.

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  • Beginning with first project on game development [closed]

    - by Tsvetan
    Today is the day I am going to start my first real game project. It will be a Universe simulator. Basically, you can build anything from tiny meteor to quazars and universes. It is going to be my project for an olympiad in IT in my country and I really want to make it perfect(at least a bronze medal). So, I would like to ask some questions about organization and development methodologies. Firstly, my plan is to make a time schedule. In it I would write my plans for the next month or two(because that is the time I have). With this exact plan I hope to make my organisation at its best. Of course, if I am doing sth faster than the schedule I would involve more features for the game and/or continue with the tempo I have. Also, for the organisation I would make a basic pseudocode(maybe) and just rewrite it so it is compilable. Like a basic skeleton of everything. The last is an idea I tought of in the moment, but if it is good I will use it. Secondly, for the development methodologies, obviously, I think of making object-oriented code and make everything perfect(a lot of testing, good code, documentation etc.). Also, I am going to make my own menu system(I read that OpenGL hasn't got very good one). Maybe I would implement it with an xml file, holding the info about position of buttons, text boxes, images and everything. Maybe I would do a specific CSS for it and so on. I think that is very good way of doing the menu system, because it makes the presentation layer separate of the logic. But, if there is a better way, I would do it the better way. For the logic, well, I don't have much to say. OO code, testing, debuging, good and fast algorithms and so on. Also, a good documentation must be written and this is the area I need to make some research in. I think that is for now. I hope I have been enough descriptive. If more questions come on my mind, I will ask them. Edit: I think of blogging every part of the project, or at least writing down everything in a file or something like that. My question is: Is my plan of how to do everything around the project good? And if not, what is necessary to be improved and what other things I can involve for making the project good.

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  • A Visual Studio Release Grows in Brooklyn

    - by andrewbrust
    Yesterday, Microsoft held its flagship launch event for Office 2010 in Manhattan.  Today, the Redmond software company is holding a local launch event for Visual Studio (VS) 2010, in Brooklyn.  How come information workers get the 212 treatment and developers are relegated to 718? Well, here’s the thing: the Brooklyn Marriott is actually a great place for an event, but you need some intimate knowledge of New York City to know that.  NBC’s Studio 8H, where the Office launch was held yesterday (and from where SNL is broadcast) is a pretty small venue, but you’d need some inside knowledge to recognize that.  Likewise, while Office 2010 is a product whose value is apparent.  Appreciating VS 2010’s value takes a bit more savvy.  Setting aside its year-based designation, this release of VS, counting the old Visual Basic releases, is the 10th version of the product.  How can a developer audience get excited about an integrated development environment when it reaches double-digit version numbers?  Well, it can be tough.  Luckily, Microsoft sent Jay Schmelzer, a Group Program Manager from the Visual Studio team in Redmond, to come tell the Brooklyn audience why they should be excited. Turns out there’s a lot of reasons.  Support fro SharePoint development is a big one.  In previous versions of VS, that support has been anemic, at best.  Shortage of SharePoint developers is a huge issue in the industry, and this should help.  There’s also built in support for Windows Azure (Microsoft’s cloud platform) and, through a download, support for the forthcoming Windows Phone 7 platform.  ASP.NET MVC, a “close-to-the-metal” Web development option that does away with the Web Forms abstraction layer, has a first-class presence in VS.  So too does jQuery, the Open Source environment that makes JavaScript development a breeze.  The jQuery support is so good that Microsoft now contributes to that Open Source project and offers IntelliSense support for it in the code editor. Speaking of the VS code editor, it now supports multi-monitor setups, zoom-in, and block selection.  If you’re not a developer, this may sound confusing and minute.  I’ll just say that for people who are developers these are little things that really contribute to productivity, and that translates into lower development costs. The really cool demo, though, was around Visual Studio 2010’s new debugging features.  This stuff is hard to showcase, but I believe it’s truly breakthrough technology: imagine being able to step backwards in time to see what might have caused a bug.  Cool?  Now imagine being able to do that, even if you weren’t the tester and weren’t present while the testing was being done.  Then imagine being able to see a video screen capture of what the tester was doing with your app when the bug occurred.  VS 2010 allows all that.  This could be the demise of the IWOMM (“it works on my machine”) syndrome. After the keynote, I asked Schmelzer if any of Microsoft’s competitors have debugging tools that come close to VS 2010’s.  His answer was an earnest “we don’t think so.”  If that’s true, that’s a big deal, and a huge advantage for developer teams who adopt it.  It will make software development much cheaper and more efficient.  Kind of like holding a launch event at the Brooklyn Marriott instead of 30 Rock in Manhattan! VS 2010 (version 10) and Office 2010 (version 14) aren’t the only new product versions Microsoft is releasing right now.  There’s also SQL Server 2008 R2 (version 10.5), Exchange 2010 (version 8, I believe), SharePoint 2010 (version 4) and, of course, Windows 7.  With so many new versions at such levels of maturity, I think it’s fair to say Microsoft has reached middle-age.  How does a company stave off a potential mid-life crisis, especially when with young Turks like Google coming along and competing so fiercely?  Hard to say.  But if focusing on core value, including value that’s hard to play into a sexy demo, is part oft the answer, then Microsoft’s doing OK.  And if some new tricks, like Windows Phone 7, can gain some traction, that might round things out nicely. Are the legacy products old tricks, or are they revised classics?  I honestly don’t know, because it’s the market’s prerogative to pass that judgement.  I can say this though: based on today’s show, I think Microsoft’s been doing its homework.

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  • Basis of definitions

    - by Yttrill
    Let us suppose we have a set of functions which characterise something: in the OO world methods characterising a type. In mathematics these are propositions and we have two kinds: axioms and lemmas. Axioms are assumptions, lemmas are easily derived from them. In C++ axioms are pure virtual functions. Here's the problem: there's more than one way to axiomatise a system. Given a set of propositions or methods, a subset of the propositions which is necessary and sufficient to derive all the others is called a basis. So too, for methods or functions, we have a desired set which must be defined, and typically every one has one or more definitions in terms of the others, and we require the programmer to provide instance definitions which are sufficient to allow all the others to be defined, and, if there is an overspecification, then it is consistent. Let me give an example (in Felix, Haskell code would be similar): class Eq[t] { virtual fun ==(x:t,y:t):bool => eq(x,y); virtual fun eq(x:t, y:t)=> x == y; virtual fun != (x:t,y:t):bool => not (x == y); axiom reflex(x:t): x == x; axiom sym(x:t, y:t): (x == y) == (y == x); axiom trans(x:t, y:t, z:t): implies(x == y and y == z, x == z); } Here it is clear: the programmer must define either == or eq or both. If both are defined, the definitions must be equivalent. Failing to define one doesn't cause a compiler error, it causes an infinite loop at run time. Defining both inequivalently doesn't cause an error either, it is just inconsistent. Note the axioms specified constrain the semantics of any definition. Given a definition of == either directly or via a definition of eq, then != is defined automatically, although the programmer might replace the default with something more efficient, clearly such an overspecification has to be consistent. Please note, == could also be defined in terms of !=, but we didn't do that. A characterisation of a partial or total order is more complex. It is much more demanding since there is a combinatorial explosion of possible bases. There is an reason to desire overspecification: performance. There also another reason: choice and convenience. So here, there are several questions: one is how to check semantics are obeyed and I am not looking for an answer here (way too hard!). The other question is: How can we specify, and check, that an instance provides at least a basis? And a much harder question: how can we provide several default definitions which depend on the basis chosen?

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  • best way to "introduce" OOP/OOD to team of experienced C++ engineers

    - by DXM
    I am looking for an efficient way, that also doesn't come off as an insult, to introduce OOP concepts to existing team members? My teammates are not new to OO languages. We've been doing C++/C# for a long time so technology itself is familiar. However, I look around and without major infusion of effort (mostly in the form of code reviews), it seems what we are producing is C code that happens to be inside classes. There's almost no use of single responsibility principle, abstractions or attempts to minimize coupling, just to name a few. I've seen classes that don't have a constructor but get memset to 0 every time they are instantiated. But every time I bring up OOP, everyone always nods and makes it seem like they know exactly what I'm talking about. Knowing the concepts is good, but we (some more than others) seem to have very hard time applying them when it comes to delivering actual work. Code reviews have been very helpful but the problem with code reviews is that they only occur after the fact so to some it seems we end up rewriting (it's mostly refactoring, but still takes lots of time) code that was just written. Also code reviews only give feedback to an individual engineer, not the entire team. I am toying with the idea of doing a presentation (or a series) and try to bring up OOP again along with some examples of existing code that could've been written better and could be refactored. I could use some really old projects that no one owns anymore so at least that part shouldn't be a sensitive issue. However, will this work? As I said most people have done C++ for a long time so my guess is that a) they'll sit there thinking why I'm telling them stuff they already know or b) they might actually take it as an insult because I'm telling them they don't know how to do the job they've been doing for years if not decades. Is there another approach which would reach broader audience than a code review would, but at the same time wouldn't feel like a punishment lecture? I'm not a fresh kid out of college who has utopian ideals of perfectly designed code and I don't expect that from anyone. The reason I'm writing this is because I just did a review of a person who actually had decent high-level design on paper. However if you picture classes: A - B - C - D, in the code B, C and D all implement almost the same public interface and B/C have one liner functions so that top-most class A is doing absolutely all the work (down to memory management, string parsing, setup negotiations...) primarily in 4 mongo methods and, for all intents and purposes, calls almost directly into D. Update: I'm a tech lead(6 months in this role) and do have full support of the group manager. We are working on a very mature product and maintenance costs are definitely letting themselves be known.

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  • "static" as a semantic clue about statelessness?

    - by leoger
    this might be a little philosophical but I hope someone can help me find a good way to think about this. I've recently undertaken a refactoring of a medium sized project in Java to go back and add unit tests. When I realized what a pain it was to mock singletons and statics, I finally "got" what I've been reading about them all this time. (I'm one of those people that needs to learn from experience. Oh well.) So, now that I'm using Spring to create the objects and wire them around, I'm getting rid of static keywords left and right. (If I could potentially want to mock it, it's not really static in the same sense that Math.abs() is, right?) The thing is, I had gotten into the habit of using static to denote that a method didn't rely on any object state. For example: //Before import com.thirdparty.ThirdPartyLibrary.Thingy; public class ThirdPartyLibraryWrapper { public static Thingy newThingy(InputType input) { new Thingy.Builder().withInput(input).alwaysFrobnicate().build(); } } //called as... ThirdPartyLibraryWrapper.newThingy(input); //After public class ThirdPartyFactory { public Thingy newThingy(InputType input) { new Thingy.Builder().withInput(input).alwaysFrobnicate().build(); } } //called as... thirdPartyFactoryInstance.newThingy(input); So, here's where it gets touchy-feely. I liked the old way because the capital letter told me that, just like Math.sin(x), ThirdPartyLibraryWrapper.newThingy(x) did the same thing the same way every time. There's no object state to change how the object does what I'm asking it to do. Here are some possible answers I'm considering. Nobody else feels this way so there's something wrong with me. Maybe I just haven't really internalized the OO way of doing things! Maybe I'm writing in Java but thinking in FORTRAN or somesuch. (Which would be impressive since I've never written FORTRAN.) Maybe I'm using staticness as a sort of proxy for immutability for the purposes of reasoning about code. That being said, what clues should I have in my code for someone coming along to maintain it to know what's stateful and what's not? Perhaps this should just come for free if I choose good object metaphors? e.g. thingyWrapper doesn't sound like it has state indepdent of the wrapped Thingy which may itself be mutable. Similarly, a thingyFactory sounds like it should be immutable but could have different strategies that are chosen among at creation. I hope I've been clear and thanks in advance for your advice!

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  • Many sources of movement in an entity system

    - by Sticky
    I'm fairly new to the idea of entity systems, having read a bunch of stuff (most usefully, this great blog and this answer). Though I'm having a little trouble understanding how something as simple as being able to manipualate the position of an object by an undefined number of sources. That is, I have my entity, which has a position component. I then have some event in the game which tells this entity to move a given distance, in a given time. These events can happen at any time, and will have different values for position and time. The result is that they'd be compounded together. In a traditional OO solution, I'd have some sort of MoveBy class, that contains the distance/time, and an array of those inside my game object class. Each frame, I'd iterate through all the MoveBy, and apply it to the position. If a MoveBy has reached its finish time, remove it from the array. With the entity system, I'm a little confused as how I should replicate this sort of behavior. If there were just one of these at a time, instead of being able to compound them together, it'd be fairly straightforward (I believe) and look something like this: PositionComponent containing x, y MoveByComponent containing x, y, time Entity which has both a PositionComponent and a MoveByComponent MoveBySystem that looks for an entity with both these components, and adds the value of MoveByComponent to the PositionComponent. When the time is reached, it removes the component from that entity. I'm a bit confused as to how I'd do the same thing with many move by's. My initial thoughts are that I would have: PositionComponent, MoveByComponent the same as above MoveByCollectionComponent which contains an array of MoveByComponents MoveByCollectionSystem that looks for an entity with a PositionComponent and a MoveByCollectionComponent, iterating through the MoveByComponents inside it, applying/removing as necessary. I guess this is a more general problem, of having many of the same component, and wanting a corresponding system to act on each one. My entities contain their components inside a hash of component type - component, so strictly have only 1 component of a particular type per entity. Is this the right way to be looking at this? Should an entity only ever have one component of a given type at all times?

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  • PHP - Internal APIs/Libraries - What makes sense?

    - by Mark Locker
    I've been having a discussion lately with some colleagues about the best way to approach a new project, and thought it'd be interesting to get some external thoughts thrown into the mix. Basically, we're redeveloping a fairly large site (written in PHP) and have differing opinions on how the platform should be setup. Requirements: The platform will need to support multiple internal websites, as well as external (non-PHP) projects which at the moment consist of a mobile app and a toolbar. We have no plans/need in the foreseeable future to open up an API externally (for use in products other than our own). My opinion: We should have a library of well documented native model classes which can be shared between projects. These models will represent everything in our database and can take advantage of object orientated features such as inheritance, traits, magic methods, etc. etc. As well as employing ORM. We can then add an API layer on top of these models which can basically accept requests and route them to the appropriate methods, translating the response so that it can be used platform independently. This routing for each method can be setup as and when it's required. Their opinion: We should have a single HTTP API which is used by all projects (internal PHP ones or otherwise). My thoughts: To me, there are a number of issues with using the sole HTTP API approach: It will be very expensive performance wise. One page request will result in several additional http requests (which although local, are still ones that Apache will need to handle). You'll lose all of the best features PHP has for OO development. From simple inheritance, to employing the likes of ORM which can save you writing a lot of code. For internal projects, the actual process makes me cringe. To get a users name, for example, a request would go out of our box, over the LAN, back in, then run through a script which calls a method, JSON encodes the output and feeds that back. That would then need to be JSON decoded, and be presented as an array ready to use. Working with arrays, as appose to objects, makes me sad in a modern PHP framework. Their thoughts (and my responses): Having one method of doing thing keeps things simple. - You'd only do things differently if you were using a different language anyway. It will become robust. - Seeing as the API will run off the library of models, I think my option would be just as robust. What do you think? I'd be really interested to hear the thoughts of others on this, especially as opinions on both sides are not founded on any past experience.

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  • Spreadsheet RDBMS

    - by John Nilsson
    I'm looking for a software (or set of software) that will let me combine spreadsheet and database workflows. Data entry in spreadsheet to enable simple entry from clipboard, analysis based on joins, unions and aggregates and pivot/data pilot summaries. So far I've only found either spreadsheets OR db applications but no good combination. OO base with calc for tables doesn't support aggregates f.ex. Google Spreadsheet + Visualizaion API doesn't support unions or joins, zoho db doesn't let me paste from clipboard. Any hints on software that could be used? Basically I'm trying to do some analysis of my personal bank transactions. Problem 1, ETL. The data has to be moved from my bank to a database. My current solution is to manually copy and paste the data into one spread sheet per account from my internet bank. Pains: Not very scriptable. Lots of scrolling to reach the point to paste. Have to apply sorting and formatting to the pasted data each time. Problem 2, analysis. I then want to aggregate the different accounts in one sweep to track transfers per type of transfer over all accounts. The actual aggregation is still unsolved because I can't find a UNION equivalent in the spreadsheets I've tried.

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  • Find and Replace several several different values all at once

    - by matt
    I have a file with multiple instances of Text_1 and Text1 and I need to replace both those strings with Text_A and TextB respectively. Currently I'm doing two Find and Replace functions on each file one that finds Text_1 and replaces it with Text_A and the other that finds Text1 and replaces it with TextB. Is there any way to do this all at once instead of having to run "Find and Replace" twice? I am using Dreamweaver CS3, but I also have Notepad++, regular Notepad, OO Writer, MS Word if those will be easier. Ideally I could do this in Dreamweaver or Notepad++ but I'm open to downloading something else to get the job done. I'd prefer not to have to do any command line stuff or create a batch file (while I'm aware of it, I don't understand it really). Edit: In case the above description isn't clear, let me explain it this way... I want to run Find & Replace 1 time in 1 document and I want it to do ALL of the following during that one Find & Replace instance: Find: Text_1 and Replace with: Text_A Find: Text1 and Replace with: TextB I am not trying to do a Find and Replace across several documents.

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  • Understanding !d command in sed with respect to saves

    - by richardh
    I have a directory of tab-delimited text files and some have comments in the first few lines that I would like to delete. I know that the first good line starts with "Mark" so I can use /^Mark/,$!d to delete these comments. After this deletion I have several other replacements that I make in the (new) first line that has variable names. My question is, why do I have to save sed's output to get my script to work? I understand that if I line is deleted, then the output doesn't proceed downstream because there is no output. But if I don't delete (i.e., !d) then why do I have to save to file? Thanks! Here is my shell script. (I'm a sed newbie, so any other feedback is also appreciated.) #!/bin/bash for file in *.txt; do mv $file $file.old1 sed -e '/^Mark/,$!d' $file.old1 > $file.old2 sed -e '1s/\([Ss]\)hareholder/\1hrhldr/g'\ -e '1s/\([Ii]\)mmediate/\1mmdt/g'\ -e '1s/\([Nn]\)umber/\1o/g'\ -e '1s/\([Cc]\)ompany/\1o/g'\ -e '1s/\([Ii]\)nformation/\1nfo/g'\ -e '1s/\([Pp]\)ercentage/\1ct/g'\ -e '1s/\([Dd]\)omestic/\1om/g'\ -e '1s/\([Gg]\)lobal/\1lbl/g'\ -e '1s/\([Cc]\)ountry/\1ntry/g'\ -e '1s/\([Ss]\)ource/\1rc/g'\ -e '1s/\([Oo]\)wnership/\1wnrshp/g'\ -e '1s/\([Uu]\)ltimate/\1ltmt/g'\ -e '1s/\([Ii]\)ncorporation/\1ncorp/g'\ -e '1s/\([Tt]\)otal/\1ot/g'\ -e '1s/\([Dd]\)irect/\1ir/g'\ $file.old2 > $file rm -f $file.old* done

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  • Neural Networks in C# using NeuronDotNet

    - by kingrichard2005
    Hello, I'm testing the NeuronDotNet library for a class assignment using C#. I have a very simple console application that I'm using to test some of the code snippets provided in the manual fro the library, the goal of the assignment is to teach the program how to distinguish between random points in a square which may or may not be within a circle that is also inside the square. So basically, which points inside the square are also inside the circle. Here is what I have so far: namespace _469_A7 { class Program { static void Main(string[] args) { //Initlaize the backpropogation network LinearLayer inputLayer = new LinearLayer(2); SigmoidLayer hiddenLayer = new SigmoidLayer(8); SigmoidLayer outputLayer = new SigmoidLayer(2); new BackpropagationConnector(inputLayer, hiddenLayer); new BackpropagationConnector(hiddenLayer, outputLayer); BackpropagationNetwork network = new BackpropagationNetwork(inputLayer, outputLayer); //Generate a training set for the ANN TrainingSet trainingSet = new TrainingSet(2, 2); //TEST: Generate random set of points and add to training set, //for testing purposes start with 10 samples; Point p; Program program = new Program(); //Used to access randdouble function Random rand = new Random(); for(int i = 0; i < 10; i++) { //These points will be within the circle radius Type A if(rand.NextDouble() > 0.5) { p = new Point(rand.NextDouble(), rand.NextDouble()); trainingSet.Add(new TrainingSample(new double[2] { p.getX(), p.getY() }, new double[2] { 1, 0 })); continue; } //These points will either be on the border or outside the circle Type B p = new Point(program.randdouble(1.0, 4.0), program.randdouble(1.0, 4.0)); trainingSet.Add(new TrainingSample(new double[2] { p.getX(), p.getY() }, new double[2] { 0, 1 })); } //Start network learning network.Learn(trainingSet, 100); //Stop network learning //network.StopLearning(); } //generates a psuedo-random double between min and max public double randdouble(double min, double max) { Random rand = new Random(); if (min > max) { return rand.NextDouble() * (min - max) + max; } else { return rand.NextDouble() * (max - min) + min; } } } //Class defines a point in X/Y coordinates public class Point { private double X; private double Y; public Point(double xVal, double yVal) { this.X = xVal; this.Y = yVal; } public double getX() { return X; } public double getY() { return Y; } } } This is basically all that I need, the only question I have is how to handle output?? More specifically, I need to output the value of the "step size" and the momentum, although it would be nice to output other information as well. Anyone with experience using NeuronDotNet, your input is appreciated.

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  • PCRE multi line matche problem

    - by Simone Margaritelli
    Hi guys, i have this C++ program (actually it's just a snippet) : #include <iostream> #include <pcre.h> #include <string> using namespace std; int main(){ string pattern = "<a\\s+href\\s*=\\s*\"([^\"]+)\"", html = "<html>\n" "<body>\n" "<a href=\"example_link_1\"/>\n" "<a href=\"example_link_2\"/>\n" "<a href=\"example_link_3\"/>\n" "</body>\n" "</html>"; int i, ccount, rc, *offsets, eoffset; const char *error; pcre *compiled; compiled = pcre_compile( pattern.c_str(), PCRE_CASELESS | PCRE_MULTILINE, &error, &eoffset, 0 ); if( !compiled ){ cerr << "Error compiling the regexp!!" << endl; return 0; } rc = pcre_fullinfo( compiled, 0, PCRE_INFO_CAPTURECOUNT, &ccount ); offsets = new int[ 3 * (ccount + 1) ]; rc = pcre_exec( compiled, 0, html.c_str(), html.length(), 0, 0, offsets, 3 * (ccount + 1) ); if( rc >= 0 ){ for( i = 1; i < rc; ++i ){ cout << "Match : " << html.substr( offsets[2*i], offsets[2*i+1] - offsets[2*i] ) << endl; } } else{ cout << "Sorry, no matches!" << endl; } delete [] offsets; return 0; } As you can see, i'm trying to match html links inside a buffer with the given regular expression (the \\s is \s escaped for C/C++ strings). But, even if in the buffer there are 3 links and the regexp is compiled with the PCRE_CASELESS and PCRE_MULTILINE flags, i match only one element : Match : example_link_1 Note: I start the loop fro index 1 because the pcre library returns the string that matched (not the match itself) as the first element, and the matches follows. What's wrong with this code? The regexp itself i think it's correct (tried in PHP for instance).

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  • Add objects to association in OnPreInsert, OnPreUpdate

    - by Dmitriy Nagirnyak
    Hi, I have an event listener (for Audit Logs) which needs to append audit log entries to the association of the object: public Company : IAuditable { // Other stuff removed for bravety IAuditLog IAuditable.CreateEntry() { var entry = new CompanyAudit(); this.auditLogs.Add(entry); return entry; } public virtual IEnumerable<CompanyAudit> AuditLogs { get { return this.auditLogs } } } The AuditLogs collection is mapped with cascading: public class CompanyMap : ClassMap<Company> { public CompanyMap() { // Id and others removed fro bravety HasMany(x => x.AuditLogs).AsSet() .LazyLoad() .Access.ReadOnlyPropertyThroughCamelCaseField() .Cascade.All(); } } And the listener just asks the auditable object to create log entries so it can update them: internal class AuditEventListener : IPreInsertEventListener, IPreUpdateEventListener { public bool OnPreUpdate(PreUpdateEvent ev) { var audit = ev.Entity as IAuditable; if (audit == null) return false; Log(audit); return false; } public bool OnPreInsert(PreInsertEvent ev) { var audit = ev.Entity as IAuditable; if (audit == null) return false; Log(audit); return false; } private static void LogProperty(IAuditable auditable) { var entry = auditable.CreateAuditEntry(); entry.CreatedAt = DateTime.Now; entry.Who = GetCurrentUser(); // Might potentially execute a query. // Also other information is set for entry here } } The problem with it though is that it throws TransientObjectException when commiting the transaction: NHibernate.TransientObjectException : object references an unsaved transient instance - save the transient instance before flushing. Type: CompanyAudit, Entity: CompanyAudit at NHibernate.Engine.ForeignKeys.GetEntityIdentifierIfNotUnsaved(String entityName, Object entity, ISessionImplementor session) at NHibernate.Type.EntityType.GetIdentifier(Object value, ISessionImplementor session) at NHibernate.Type.ManyToOneType.NullSafeSet(IDbCommand st, Object value, Int32 index, Boolean[] settable, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.WriteElement(IDbCommand st, Object elt, Int32 i, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.PerformInsert(Object ownerId, IPersistentCollection collection, IExpectation expectation, Object entry, Int32 index, Boolean useBatch, Boolean callable, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.Recreate(IPersistentCollection collection, Object id, ISessionImplementor session) at NHibernate.Action.CollectionRecreateAction.Execute() at NHibernate.Engine.ActionQueue.Execute(IExecutable executable) at NHibernate.Engine.ActionQueue.ExecuteActions(IList list) at NHibernate.Engine.ActionQueue.ExecuteActions() at NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions(IEventSource session) at NHibernate.Event.Default.DefaultFlushEventListener.OnFlush(FlushEvent event) at NHibernate.Impl.SessionImpl.Flush() at NHibernate.Transaction.AdoTransaction.Commit() As the cascading is set to All I expected NH to handle this. I also tried to modify the collection using state but pretty much the same happens. So the question is what is the last chance to modify object's associations before it gets saved? Thanks, Dmitriy.

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  • How to add objects to association in OnPreInsert, OnPreUpdate

    - by Dmitriy Nagirnyak
    Hi, I have an event listener (for Audit Logs) which needs to append audit log entries to the association of the object: public Company : IAuditable { // Other stuff removed for bravety IAuditLog IAuditable.CreateEntry() { var entry = new CompanyAudit(); this.auditLogs.Add(entry); return entry; } public virtual IEnumerable<CompanyAudit> AuditLogs { get { return this.auditLogs } } } The AuditLogs collection is mapped with cascading: public class CompanyMap : ClassMap<Company> { public CompanyMap() { // Id and others removed fro bravety HasMany(x => x.AuditLogs).AsSet() .LazyLoad() .Access.ReadOnlyPropertyThroughCamelCaseField() .Cascade.All(); } } And the listener just asks the auditable object to create log entries so it can update them: internal class AuditEventListener : IPreInsertEventListener, IPreUpdateEventListener { public bool OnPreUpdate(PreUpdateEvent ev) { var audit = ev.Entity as IAuditable; if (audit == null) return false; Log(audit); return false; } public bool OnPreInsert(PreInsertEvent ev) { var audit = ev.Entity as IAuditable; if (audit == null) return false; Log(audit); return false; } private static void LogProperty(IAuditable auditable) { var entry = auditable.CreateAuditEntry(); entry.CreatedAt = DateTime.Now; entry.Who = GetCurrentUser(); // Might potentially execute a query. // Also other information is set for entry here } } The problem with it though is that it throws TransientObjectException when commiting the transaction: NHibernate.TransientObjectException : object references an unsaved transient instance - save the transient instance before flushing. Type: PropConnect.Model.UserAuditLog, Entity: PropConnect.Model.UserAuditLog at NHibernate.Engine.ForeignKeys.GetEntityIdentifierIfNotUnsaved(String entityName, Object entity, ISessionImplementor session) at NHibernate.Type.EntityType.GetIdentifier(Object value, ISessionImplementor session) at NHibernate.Type.ManyToOneType.NullSafeSet(IDbCommand st, Object value, Int32 index, Boolean[] settable, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.WriteElement(IDbCommand st, Object elt, Int32 i, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.PerformInsert(Object ownerId, IPersistentCollection collection, IExpectation expectation, Object entry, Int32 index, Boolean useBatch, Boolean callable, ISessionImplementor session) at NHibernate.Persister.Collection.AbstractCollectionPersister.Recreate(IPersistentCollection collection, Object id, ISessionImplementor session) at NHibernate.Action.CollectionRecreateAction.Execute() at NHibernate.Engine.ActionQueue.Execute(IExecutable executable) at NHibernate.Engine.ActionQueue.ExecuteActions(IList list) at NHibernate.Engine.ActionQueue.ExecuteActions() at NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions(IEventSource session) at NHibernate.Event.Default.DefaultFlushEventListener.OnFlush(FlushEvent event) at NHibernate.Impl.SessionImpl.Flush() at NHibernate.Transaction.AdoTransaction.Commit() As the cascading is set to All I expected NH to handle this. I also tried to modify the collection using state but pretty much the same happens. So the question is what is the last chance to modify object's associations before it gets saved? Thanks, Dmitriy.

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  • Why do I get rows of zeros in my 2D fft?

    - by Nicholas Pringle
    I am trying to replicate the results from a paper. "Two-dimensional Fourier Transform (2D-FT) in space and time along sections of constant latitude (east-west) and longitude (north-south) were used to characterize the spectrum of the simulated flux variability south of 40degS." - Lenton et al(2006) The figures published show "the log of the variance of the 2D-FT". I have tried to create an array consisting of the seasonal cycle of similar data as well as the noise. I have defined the noise as the original array minus the signal array. Here is the code that I used to plot the 2D-FT of the signal array averaged in latitude: import numpy as np from numpy import ma from matplotlib import pyplot as plt from Scientific.IO.NetCDF import NetCDFFile ### input directory indir = '/home/nicholas/data/' ### get the flux data which is in ### [time(5day ave for 10 years),latitude,longitude] nc = NetCDFFile(indir + 'CFLX_2000_2009.nc','r') cflux_southern_ocean = nc.variables['Cflx'][:,10:50,:] cflux_southern_ocean = ma.masked_values(cflux_southern_ocean,1e+20) # mask land nc.close() cflux = cflux_southern_ocean*1e08 # change units of data from mmol/m^2/s ### create an array that consists of the seasonal signal fro each pixel year_stack = np.split(cflux, 10, axis=0) year_stack = np.array(year_stack) signal_array = np.tile(np.mean(year_stack, axis=0), (10, 1, 1)) signal_array = ma.masked_where(signal_array > 1e20, signal_array) # need to mask ### average the array over latitude(or longitude) signal_time_lon = ma.mean(signal_array, axis=1) ### do a 2D Fourier Transform of the time/space image ft = np.fft.fft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log(mgft) log_mgft= np.log(mgft) Every second row of the ft consists completely of zeros. Why is this? Would it be acceptable to add a randomly small number to the signal to avoid this. signal_time_lon = signal_time_lon + np.random.randint(0,9,size=(730, 182))*1e-05 EDIT: Adding images and clarify meaning The output of rfft2 still appears to be a complex array. Using fftshift shifts the edges of the image to the centre; I still have a power spectrum regardless. I expect that the reason that I get rows of zeros is that I have re-created the timeseries for each pixel. The ft[0, 0] pixel contains the mean of the signal. So the ft[1, 0] corresponds to a sinusoid with one cycle over the entire signal in the rows of the starting image. Here are is the starting image using following code: plt.pcolormesh(signal_time_lon); plt.colorbar(); plt.axis('tight') Here is result using following code: ft = np.fft.rfft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log1p(mgft) plt.pcolormesh(log_ps); plt.colorbar(); plt.axis('tight') It may not be clear in the image but it is only every second row that contains completely zeros. Every tenth pixel (log_ps[10, 0]) is a high value. The other pixels (log_ps[2, 0], log_ps[4, 0] etc) have very low values.

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  • How does the CLR (.NET) internally allocate and pass around custom value types (structs)?

    - by stakx
    Question: Do all CLR value types, including user-defined structs, live on the evaluation stack exclusively, meaning that they will never need to be reclaimed by the garbage-collector, or are there cases where they are garbage-collected? Background: I have previously asked a question on SO about the impact that a fluent interface has on the runtime performance of a .NET application. I was particuarly worried that creating a large number of very short-lived temporary objects would negatively affect runtime performance through more frequent garbage-collection. Now it has occured to me that if I declared those temporary objects' types as struct (ie. as user-defined value types) instead of class, the garbage collector might not be involved at all if it turns out that all value types live exclusively on the evaluation stack. What I've found out so far: I did a brief experiment to see what the differences are in the CIL generated for user-defined value types and reference types. This is my C# code: struct SomeValueType { public int X; } class SomeReferenceType { public int X; } . . static void TryValueType(SomeValueType vt) { ... } static void TryReferenceType(SomeReferenceType rt) { ... } . . var vt = new SomeValueType { X = 1 }; var rt = new SomeReferenceType { X = 2 }; TryValueType(vt); TryReferenceType(rt); And this is the CIL generated for the last four lines of code: .locals init ( [0] valuetype SomeValueType vt, [1] class SomeReferenceType rt, [2] valuetype SomeValueType <>g__initLocal0, // [3] class SomeReferenceType <>g__initLocal1, // why are these generated? [4] valuetype SomeValueType CS$0$0000 // ) L_0000: ldloca.s CS$0$0000 L_0002: initobj SomeValueType // no newobj required, instance already allocated L_0008: ldloc.s CS$0$0000 L_000a: stloc.2 L_000b: ldloca.s <>g__initLocal0 L_000d: ldc.i4.1 L_000e: stfld int32 SomeValueType::X L_0013: ldloc.2 L_0014: stloc.0 L_0015: newobj instance void SomeReferenceType::.ctor() L_001a: stloc.3 L_001b: ldloc.3 L_001c: ldc.i4.2 L_001d: stfld int32 SomeReferenceType::X L_0022: ldloc.3 L_0023: stloc.1 L_0024: ldloc.0 L_0025: call void Program::TryValueType(valuetype SomeValueType) L_002a: ldloc.1 L_002b: call void Program::TryReferenceType(class SomeReferenceType) What I cannot figure out from this code is this: Where are all those local variables mentioned in the .locals block allocated? How are they allocated? How are they freed? Why are so many anonymous local variables needed and copied to-and-fro only to initialize my two local variables rt and vt?

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