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• RPi and Java Embedded GPIO: Writing Java code to blink LED

  - by hinkmond

  So, you've followed the previous steps to install Java Embedded on your Raspberry Pi ?, you went to Fry's and picked up some jumper wires, LEDs, and resistors ?, you hooked up the wires, LED, and resistor the the correct pins ?, and now you want to start programming in Java on your RPi? Yes? ???????! OK, then... Here we go. You can use the following source code to blink your first LED on your RPi using Java. In the code you can see that I'm not using any complicated gpio libraries like wiringpi or pi4j, and I'm not doing any low-level pin manipulation like you can in C. And, I'm not using python (hell no!). This is Java programming, so we keep it simple (and more readable) than those other programming languages. See: Write Java code to do this In the Java code, I'm opening up the RPi Debian Wheezy well-defined file handles to control the GPIO ports. First I'm resetting everything using the unexport/export file handles. (On the RPi, if you open the well-defined file handles and write certain ASCII text to them, you can drive your GPIO to perform certain operations. See this GPIO reference). Next, I write a "1" then "0" to the value file handle of the GPIO0 port (see the previous pinout diagram). That makes the LED blink. Then, I loop to infinity. Easy, huh? import java.io.* /* * Java Embedded Raspberry Pi GPIO app */ package jerpigpio; import java.io.FileWriter; /** * * @author hinkmond */ public class JerpiGPIO { static final String GPIO_OUT = "out"; static final String GPIO_ON = "1"; static final String GPIO_OFF = "0"; static final String GPIO_CH00="0"; /** * @param args the command line arguments */ public static void main(String[] args) { FileWriter commandFile; try { /*** Init GPIO port for output ***/ // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); // Reset the port unexportFile.write(GPIO_CH00); unexportFile.flush(); // Set the port for use exportFile.write(GPIO_CH00); exportFile.flush(); // Open file handle to port input/output control FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio"+GPIO_CH00+"/direction"); // Set port for output directionFile.write(GPIO_OUT); directionFile.flush(); /*--- Send commands to GPIO port ---*/ // Opne file handle to issue commands to GPIO port commandFile = new FileWriter("/sys/class/gpio/gpio"+GPIO_CH00+"/value"); // Loop forever while (true) { // Set GPIO port ON commandFile.write(GPIO_ON); commandFile.flush(); // Wait for a while java.lang.Thread.sleep(200); // Set GPIO port OFF commandFile.write(GPIO_OFF); commandFile.flush(); // Wait for a while java.lang.Thread.sleep(200); } } catch (Exception exception) { exception.printStackTrace(); } } } Hinkmond

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• Direct3D11 and SharpDX - How to pass a model instance's world matrix as an input to a vertex shader

  - by Nathan Ridley

  Using Direct3D11, I'm trying to pass a matrix into my vertex shader from the instance buffer that is associated with a given model's vertices and I can't seem to construct my InputLayout without throwing an exception. The shader looks like this: cbuffer ConstantBuffer : register(b0) { matrix World; matrix View; matrix Projection; } struct VIn { float4 position: POSITION; matrix instance: INSTANCE; float4 color: COLOR; }; struct VOut { float4 position : SV_POSITION; float4 color : COLOR; }; VOut VShader(VIn input) { VOut output; output.position = mul(input.position, input.instance); output.position = mul(output.position, View); output.position = mul(output.position, Projection); output.color = input.color; return output; } The input layout looks like this: var elements = new[] { new InputElement("POSITION", 0, Format.R32G32B32_Float, 0, 0, InputClassification.PerVertexData, 0), new InputElement("INSTANCE", 0, Format.R32G32B32A32_Float, 0, 0, InputClassification.PerInstanceData, 1), new InputElement("COLOR", 0, Format.R32G32B32A32_Float, 12, 0) }; InputLayout = new InputLayout(device, signature, elements); The buffer initialization looks like this: public ModelDeviceData(Model model, Device device) { Model = model; var vertices = Helpers.CreateBuffer(device, BindFlags.VertexBuffer, model.Vertices); var instances = Helpers.CreateBuffer(device, BindFlags.VertexBuffer, Model.Instances.Select(m => m.WorldMatrix).ToArray()); VerticesBufferBinding = new VertexBufferBinding(vertices, Utilities.SizeOf<ColoredVertex>(), 0); InstancesBufferBinding = new VertexBufferBinding(instances, Utilities.SizeOf<Matrix>(), 0); IndicesBuffer = Helpers.CreateBuffer(device, BindFlags.IndexBuffer, model.Triangles); } The buffer creation helper method looks like this: public static Buffer CreateBuffer<T>(Device device, BindFlags bindFlags, params T[] items) where T : struct { var len = Utilities.SizeOf(items); var stream = new DataStream(len, true, true); foreach (var item in items) stream.Write(item); stream.Position = 0; var buffer = new Buffer(device, stream, len, ResourceUsage.Default, bindFlags, CpuAccessFlags.None, ResourceOptionFlags.None, 0); return buffer; } The line that instantiates the InputLayout object throws this exception: *HRESULT: [0x80070057], Module: [General], ApiCode: [E_INVALIDARG/Invalid Arguments], Message: The parameter is incorrect.* Note that the data for each model instance is simply an instance of SharpDX.Matrix. EDIT Based on Tordin's answer, it sems like I have to modify my code like so: var elements = new[] { new InputElement("POSITION", 0, Format.R32G32B32_Float, 0, 0, InputClassification.PerVertexData, 0), new InputElement("INSTANCE0", 0, Format.R32G32B32A32_Float, 0, 0, InputClassification.PerInstanceData, 1), new InputElement("INSTANCE1", 1, Format.R32G32B32A32_Float, 0, 0, InputClassification.PerInstanceData, 1), new InputElement("INSTANCE2", 2, Format.R32G32B32A32_Float, 0, 0, InputClassification.PerInstanceData, 1), new InputElement("INSTANCE3", 3, Format.R32G32B32A32_Float, 0, 0, InputClassification.PerInstanceData, 1), new InputElement("COLOR", 0, Format.R32G32B32A32_Float, 12, 0) }; and in the shader: struct VIn { float4 position: POSITION; float4 instance0: INSTANCE0; float4 instance1: INSTANCE1; float4 instance2: INSTANCE2; float4 instance3: INSTANCE3; float4 color: COLOR; }; VOut VShader(VIn input) { VOut output; matrix world = { input.instance0, input.instance1, input.instance2, input.instance3 }; output.position = mul(input.position, world); output.position = mul(output.position, View); output.position = mul(output.position, Projection); output.color = input.color; return output; } However I still get an exception.

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• Copy TFS Build Definitions between Projects and Collections

  - by Jakob Ehn

  Originally posted on: http://geekswithblogs.net/jakob/archive/2014/06/05/copy-tfs-build-definitions-between-projects-and-collections.aspxThe last couple of years it has become apparent that using multiple team projects in TFS is generally a bad idea. There are of course exceptions to this, but there are a lot ot things that becomes much easier to do when you put all of your projects and team in the same team project. Fellow ALM MVP Martin Hinshelwood has blogged about this several times, as well as other people in the community. In particular, using the backlog and portfolio management tools makes much more sense when everything is located in the same team project. Consolidating multiple team projects into one is not that easy unfortunately, it involves migrating source code, work items, reports etc.  Another thing that also need to be migrated is build definitions. It is possible to clone build definitions within the same team project using the TFS power tools. The Community TFS Build Manager also lets you clone build definitions to other team projects. But there is no tool that allows you to clone/copy a build definition to another collection. So, I whipped up a simple console application that let you do this. The tool can be downloaded from https://onedrive.live.com/redir?resid=EE034C9F620CD58D!8162&authkey=!ACTr56v1QVowzuE&ithint=file%2c.zip   Using CopyTFSBuildDefinitions You use the tool like this: CopyTFSBuildDefinitions  SourceCollectionUrl  SourceTeamProject  BuildDefinitionName  DestinationCollectionUrl  DestinationTeamProject [NewDefinitionName] Arguments SourceCollectionUrl The URL to the TFS collection that contains the team project with the build definition that you want to copy SourceTeamProject The name of the team project that contains the build definition BuildDefinitionName Name of the build definition DestinationCollectionUrl The URL to the TFS collection that contains the team project that you want to copy your build definition to DestinationTeamProject The name of the team project in the destination collection NewDefinitionName (Optional) Use this to override the name of the new build definition. If you don’t specify this, the name will the same as the original one Example: CopyTFSBuildDefinitions  https://jakob.visualstudio.com DemoProject  WebApplication.CI https://anotheraccount.visualstudio.com     Notes Since we are (potentially) create a build definition in a new collection, there is no guarantee that the various paths that are defined in the build definition exist in the new collection. For example, a build definition refers to server paths in TFVC or repos + branches in TFGit. It also refers to build controllers that definitely don’t exist in the new collection. So there will be some cleanup to do after you copy your build definitions. You can fix some of these using the Community TFS Build Manager, for example it is very easy to apply the correct build controller to a set of build definitions The problem stated above also applies to build process templates. However, the tool tries to find a build process template in the new team project with the same file name as the one that existed in the old team project. If it finds one, it will be used for the new build definition. Otherwise is will use the default build template If you want to run the tool for many build definitions, you can use this SQL scripts, compliments of Mr. Scrum/ALM MVP Richard Hundhausen to generate the necessary commands: USE Tfs_Collection GO SELECT 'CopyTFSBuildDefinitions.exe http://SERVER:8080/tfs/collection "' + P.ProjectName + '" "' + REPLACE(BD.DefinitionName,'\','') + '" http://NEWSERVER:8080/tfs/COLLECTION TEAMPROJECT'   FROM tbl_Project P        INNER JOIN tbl_BuildGroup BG on BG.TeamProject = P.ProjectUri        INNER JOIN tbl_BuildDefinition BD on BD.GroupId = BG.GroupId   ORDER BY P.ProjectName, BD.DefinitionName   Hope that helps, let me know if you have any problems with the tool or if you find it useful

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• How do I deal with a third party application that has embedded hints that result in a sub-optimal execution plan in my environment?

  - by Maria Colgan

  I have gotten many variations on this question recently as folks begin to upgrade to Oracle Database 11g and there have been several posts on this blog and on others describing how to use SQL Plan Management (SPM) so that a non-hinted SQL statement can use a plan generated with hints. But what if the hint is supplied in the third party application and is causing performance regressions on your system? You can actually use a very similar technique to the ones shown before but this time capture the un-hinted plan and have the hinted SQL statement use that plan instead. Below is an example that demonstrates the necessary steps. 1. We will begin by running the hinted statement 2. After examining the execution plan we can see it is suboptimal because of a bad join order. 3. In order to use SPM to correct the problem we must create a SQL plan baseline for the statement. In order to create a baseline we will need the SQL_ID for the hinted statement. Easy place to get it is in V$SQL. 4. A SQL plan baseline can be created using a SQL_ID and DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE. This will capture the existing plan for this SQL_ID from the shared pool and store in the SQL plan baseline. 5. We can check the SQL plan baseline got created successfully by querying DBA_SQL_PLAN_BASELINES. 6. When you manually create a SQL plan baseline the first plan added is automatically accepted and enabled. We know that the hinted plan is poorly performing plan so we will disable it using DBMS_SPM.ALTER_SQL_PLAN_BASELINE. Disabling the plan tells the optimizer that this plan not a good plan, however since there is no alternative plan at this point the optimizer will still continue to use this plan until we provide a better one. 7. Now let's run the statement without the hint. 8. Looking at the execution plan we can see that the join order is different. The plan without the hint also has a lower cost (3X lower), which indicates it should perform better. 9. In order to map the un-hinted plan to the hinted SQL statement we need to add the plan to the SQL plan baseline for the hinted statement. We can do this using DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE but we will need the SQL_ID and  PLAN_HASH_VALUE for the non-hinted statement, which we can find in V$SQL. 10. Now we can add the non-hinted plan to the SQL plan baseline of the hinted SQL statement using DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE. This time we need to pass a few more arguments. We will use the SQL_ID and PLAN_HASH_VALUE of the non-hinted statement but the SQL_HANDLE of the hinted statement. 11. The SQL plan baseline for our statement now has two plans. But only the newly added plan (SQL_PLAN_gbpcg3f67pc788a6d8911) is enabled and accepted. This tells the Optimizer that this is the plan it should use for this statement. We can confirm that the correct plan (non-hinted) will be selected for the statement from now on by re-executing the hinted statement and checking its execution plan.

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• JustMock is here !!

  - by mehfuzh

  As announced earlier by Hristo Kosev at Telerik blogs , we have started giving out JustMock builds from today. This is the first of early builds before the official Q2 release and we are pretty excited to get your feedbacks. Its pretty early to say anything on it. It actually depends on your feedback. To add few, with JustMock we tried to build a mocking tool with simple and intuitive syntax as possible excluding more and more noises and avoiding any smell that can be made to your code [We are still trying everyday] and we want to make the tool even better with your help. JustMock can be used to mock virtually anything. Moreover, we left an option open that it can be used to reduce / elevate the features  just though a single click. We tried to make a strong API and make stuffs fluent and guided as possible so that you never have the chance to get de-railed. Our syntax is AAA (Arrange – Act – Assert) , we don’t believe in Record – Reply model which some of the smarter mocking tools are planning to remove from their coming release or even don’t have [its always fun to lean from each other]. Overall more signals equals more complexity , reminds me of 37 signals :-). Currently, here are the things you can do with JustMock ( will cover more in-depth in coming days) Proxied mode Mock interfaces and class with virtuals Mock properties that includes indexers Set raise event for specific calls Use matchers to control mock arguments Assert specific occurrence of a mocked calls. Assert using matchers Do recursive mocks Do Sequential mocking ( same method with argument returns different values or perform different tasks) Do strict mocking (by default and i prefer loose , so that i can use it as stubs) Elevated mode Mock static calls Mock final class Mock sealed classes Mock Extension methods Partially mock a  class member directly using Mock.Arrange Mock MsCorlib (we will support more and more members in coming days) , currently we support FileInfo, File and DateTime. These are few, you need to take a look at the test project that is provided with the build to find more [Along with the document]. Also, one of feature that will i will be using it for my next OS projects is the ability to run it separately in  proxied mode which makes it easy to redistribute and do some personal development in a more DI model and my option to elevate as it go.   I’ve surely forgotten tons of other features to mention that i will cover time but  don’t for get the URL : www.telerik.com/justmock   Finally a little mock code:   var lvMock = Mock.Create<ILoveJustMock>();    // set your goal  Mock.Arrange(() => lvMock.Response(Arg.Any<string>())).Returns((int result) => result);    //perform  string ret =  lvMock.Echo("Yes");    Assert.Equal(ret, "Yes");  // make sure everything is fine  Mock.Assert(() => lvMock.Echo("Yes"), Occurs.Once());   Hope that helps to get started,  will cover if not :-).

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• Stuck due to "knowing too much"

  - by Ran Biron

  Note more discussion at http://news.ycombinator.com/item?id=4037794 Welcome Hacker News Visitors! While HN is a fine forum for discussion and debate, Programmers - Stack Exchange is not. From the FAQ: If your motivation for asking the question is “I would like to participate in a discussion about ____”, then you should not be asking here. However, if your motivation is “I would like others to explain ____ to me”, then you are probably OK. (Discussions are of course welcome in our real time web chat.) Currently, this question is viewed by the membership of Programmers.SE as more likely to provoke unproductive discussion than constructive answers; while debates on its form and future are conducted, it will be locked to prevent arguments and vandalism. -- Shog9 I have a relatively simple development task, but every time I try to attack it, I end up spiraling in deep thoughts - how could it extending the future, what are the 2nd generation clients going to need, how does it affect "non functional" aspects (e.g. Performance, authorization...), how would it best be architectured to allow change... I remember myself a while ago, younger and, perhaps, more eager. The "me" I was then wouldn't have given a thought about all that - he would've gone ahead and wrote something, then rewrote it, then rewrote it again (and again...). The "me" today is more hesitant, more careful. I find it much easier today to sit and plan and instruct other people on how to do things than to actually go ahead and do them myself - not because I don't like to code - the opposite, I love to! - but because every time I sit at the keyboard, I end up in that same annoying place. Is this wrong? Is this a natural evolution, or did I drive myself into a rut? Fair disclosure - in the past I was a developer, today my job title is a "system architect". Good luck figuring what it means - but that's the title. Wow. I honestly didn't expect this question to generate that many responses. I'll try to sum it up. Reasons: Analysis paralysis / Over engineering / gold plating / (any other "too much thinking up-front can hurt you"). Too much experience for the given task. Not focusing on what's important. Not enough experience (and realizing that). Solutions (not matched to reasons): Testing first. Start coding (+ for fun) One to throw away (+ one API to throw away). Set time constraints. Strip away the fluff, stay with the stuff. Make flexible code (kinda opposite to "one to throw away", no?). Thanks to everyone - I think the major benefit here was to realize that I'm not alone in this experience. I have, actually, already started coding and some of the too-big things have fallen off, naturally. Since this question is closed, I'll accept the answer with most votes as of today. When/if it changes - I'll try to follow.

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• F1 Pit Pragmatics

  - by mikef

  "I hate computers. No, really, I hate them. I love the communications they facilitate, I love the conveniences they provide to my life. but I actually hate the computers themselves." - Scott Merrill, 'I hate computers: confessions of a Sysadmin' If Scott's goal was to polarize opinion and trigger raging arguments over the 'real reasons why computers suck', then he certainly succeeded. Impassioned vitriol sits side-by-side with rational debate. Yet Scott's fundamental point is absolutely on the money - Computers are a means to an end. The IT industry is finally starting to put weight behind the notion that good User Experience is an absolutely crucial goal, a cause championed by the likes of Microsoft's Bill Buxton, and which Apple's increasingly ubiquitous touch screen interface exemplifies. However, that doesn't change the fact that, occasionally, you just have to man up and deal with complex systems. In fact, sometimes you just need to sacrifice everything else in the name of performance. You'll find a perfect example of this Faustian bargain in Trevor Clarke's fascinating look into the (diabolical) IT infrastructure of modern F1 racing - high performance, high availability. high everything. To paraphrase, each car has up to 100 sensors, transmitting around 30Gb of data over the course of a race (70% in real-time). This data is then processed by no less than 3 servers (per car) so that the engineers in the pit have access to telemetry, strategy information, timing feeds, a connection back to the operations room in the team's home base - the list goes on. All of this while the servers are exposed "to carbon dust, oil, vibration, rain, heat, [and] variable power". Now, this is admittedly an extreme context where there's no real choice but to use complex systems where ease-of-use is, at best, a secondary concern. The flip-side is seen in small-scale personal computing such as that seen in Apple's iDevices, which are incredibly intuitive but limited in their scope. In terms of what kinds of systems they prefer to use, I suspect that most SysAdmins find themselves somewhere along this axis of Power vs. Usability, and which end of this axis you resonate with also hints at where you think the IT industry should focus its energy. Do you see yourself in the F1 pit, making split-second decisions, wrestling with information flows and reticent hardware to bend them to your will? If so, I imagine you feel that computers are subtle tools which need to be tuned and honed, using the advanced knowledge possessed only by responsible SysAdmins (If you have an iPhone, I suspect it's jail-broken). If the machines throw enigmatic errors, it's the price of flexibility and raw power. Alternatively, would you prefer to have your role more accessible, with users empowered by knowledge, spreading the load of managing IT environments? In that case, then you want hardware and software to have User Experience as their primary focus, and are of the "means to an end" school of thought (you're probably also fed up with users not listening to you when you try and help). At its heart, the dichotomy is between raw power (which might be difficult to use) and ease-of-use (which might have some limitations, but you can be up and running immediately). Of course, the ultimate goal is a fusion of flexibility, power and usability all in one system. It's achievable in specific software environments, and Red Gate considers it a target worth aiming for, but in other cases it's a goal right up there with cold fusion. I think it'll be a long time before we see it become ubiquitous. In the meantime, are you Power-Hungry or a Champion of Usability? Cheers, Michael Francis Simple Talk SysAdmin Editor

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• Converting from mp4 to Xvid avi using avconv?

  - by Ricardo Gladwell

  I normally use avidemux to convert mp4s to Xvid AVI for my Philips Streamium SLM5500. Normally I select MPEG-4 ASP (Xvid) at Two Pass with an average bitrate f 1500kb/s for video and AC3 (lav) audio and it converts correctly. However, I'm trying to using avconv so I can automate the process with a script, but when I do this the video stutters and stops playing part way through. I have a suspicion its something to do with a faulty audio conversion. The commands I'm using are as follows: avconv -y -i video.mp4 -pass 1 -vtag xvid -c:a ac3 -b:a 128k -b:v 1500k -f avi /dev/null avconv -y -i video.mp4 -pass 2 -vtag xvid -c:a ac3 -b:a 128k -b:v 1500k -f avi video.avi There is a bewildering array of arguments for avconv. Is there something I'm doing wrong? Is there a way I can script avidemux from a headless server? Please see command line output: $ avconv -y -i video.mp4 -pass 1 -vtag xvid -an -b:v 1500k -f avi /dev/null avconv version 0.8.5-6:0.8.5-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers built on Jan 24 2013 14:49:20 with gcc 4.7.2 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4': Metadata: major_brand : isom minor_version : 1 compatible_brands: isomavc1 creation_time : 2013-02-04 13:53:38 Duration: 00:44:09.16, start: 0.000000, bitrate: 669 kb/s Stream #0.0(und): Video: h264 (High), yuv420p, 720x404 [PAR 1:1 DAR 180:101], 538 kb/s, 25 fps, 25 tbr, 100 tbn, 50 tbc Metadata: creation_time : 2013-02-04 13:53:38 Stream #0.1(und): Audio: ac3, 44100 Hz, stereo, s16, 127 kb/s Metadata: creation_time : 2013-02-04 13:53:42 [buffer @ 0x7f4c40] w:720 h:404 pixfmt:yuv420p Output #0, avi, to '/dev/null': Metadata: major_brand : isom minor_version : 1 compatible_brands: isomavc1 creation_time : 2013-02-04 13:53:38 ISFT : Lavf53.21.1 Stream #0.0(und): Video: mpeg4, yuv420p, 720x404 [PAR 1:1 DAR 180:101], q=2-31, pass 1, 1500 kb/s, 25 tbn, 25 tbc Metadata: creation_time : 2013-02-04 13:53:38 Stream mapping: Stream #0:0 -> #0:0 (h264 -> mpeg4) Press ctrl-c to stop encoding frame=66227 fps=328 q=2.0 Lsize= 0kB time=2649.16 bitrate= 0.0kbits/s video:401602kB audio:0kB global headers:0kB muxing overhead -100.000000% $ avconv -y -i video.mp4 -pass 2 -vtag xvid -c:a ac3 -b:a 128k -b:v 1500k -f avi video.avi avconv version 0.8.5-6:0.8.5-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers built on Jan 24 2013 14:49:20 with gcc 4.7.2 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4': Metadata: major_brand : isom minor_version : 1 compatible_brands: isomavc1 creation_time : 2013-02-04 13:53:38 Duration: 00:44:09.16, start: 0.000000, bitrate: 669 kb/s Stream #0.0(und): Video: h264 (High), yuv420p, 720x404 [PAR 1:1 DAR 180:101], 538 kb/s, 25 fps, 25 tbr, 100 tbn, 50 tbc Metadata: creation_time : 2013-02-04 13:53:38 Stream #0.1(und): Audio: ac3, 44100 Hz, stereo, s16, 127 kb/s Metadata: creation_time : 2013-02-04 13:53:42 [buffer @ 0x12b4f00] w:720 h:404 pixfmt:yuv420p Incompatible sample format 's16' for codec 'ac3', auto-selecting format 'flt' [mpeg4 @ 0x12b3ec0] [lavc rc] Using all of requested bitrate is not necessary for this video with these parameters. Output #0, avi, to 'video.avi': Metadata: major_brand : isom minor_version : 1 compatible_brands: isomavc1 creation_time : 2013-02-04 13:53:38 ISFT : Lavf53.21.1 Stream #0.0(und): Video: mpeg4, yuv420p, 720x404 [PAR 1:1 DAR 180:101], q=2-31, pass 2, 1500 kb/s, 25 tbn, 25 tbc Metadata: creation_time : 2013-02-04 13:53:38 Stream #0.1(und): Audio: ac3, 44100 Hz, stereo, flt, 128 kb/s Metadata: creation_time : 2013-02-04 13:53:42 Stream mapping: Stream #0:0 -> #0:0 (h264 -> mpeg4) Stream #0:1 -> #0:1 (ac3 -> ac3) Press ctrl-c to stop encoding Input stream #0:1 frame changed from rate:44100 fmt:s16 ch:2 to rate:44100 fmt:flt ch:2 frame=66227 fps=284 q=2.2 Lsize= 458486kB time=2649.13 bitrate=1417.8kbits/s video:413716kB audio:41393kB global headers:0kB muxing overhead 0.741969%

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• Do we still have a case against the goto statement? [closed]

  - by FredOverflow

  Possible Duplicate: Is it ever worthwhile using goto? In a recent article, Andrew Koenig writes: When asked why goto statements are harmful, most programmers will say something like "because they make programs hard to understand." Press harder, and you may well hear something like "I don't really know, but that's what I was taught." For that reason, I'd like to summarize Dijkstra's arguments. He then shows two program fragments, one without a goto and and one with a goto: if (n < 0) n = 0; Assuming that n is a variable of a built-in numeric type, we know that after this code, n is nonnegative. Suppose we rewrite this fragment: if (n >= 0) goto nonneg; n = 0; nonneg: ; In theory, this rewrite should have the same effect as the original. However, rewriting has changed something important: It has opened the possibility of transferring control to nonneg from anywhere else in the program. I emphasized the part that I don't agree with. Modern languages like C++ do not allow goto to transfer control arbitrarily. Here are two examples: You cannot jump to a label that is defined in a different function. You cannot jump over a variable initialization. Now consider composing your code of tiny functions that adhere to the single responsibility principle: int clamp_to_zero(int n) { if (n >= 0) goto n_is_not_negative: n = 0; n_is_not_negative: return n; } The classic argument against the goto statement is that control could have transferred from anywhere inside your program to the label n_is_not_negative, but this simply is not (and was never) true in C++. If you try it, you will get a compiler error, because labels are scoped. The rest of the program doesn't even see the name n_is_not_negative, so it's just not possible to jump there. This is a static guarantee! Now, I'm not saying that this version is better then the one without the goto, but to make the latter as expressive as the first one, we would at least have to insert a comment, or even better yet, an assertion: int clamp_to_zero(int n) { if (n < 0) n = 0; // n is not negative at this point assert(n >= 0); return n; } Note that you basically get the assertion for free in the goto version, because the condition n >= 0 is already written in line 1, and n = 0; satisfies the condition trivially. But that's just a random observation. It seems to me that "don't use gotos!" is one of those dogmas like "don't use multiple returns!" that stem from a time where the real problem were functions of hundreds or even thousand of lines of code. So, do we still have a case against the goto statement, other than that it is not particularly useful? I haven't written a goto in at least a decade, but it's not like I was running away in terror whenever I encountered one. 1 Ideally, I would like to see a strong and valid argument against gotos that still holds when you adhere to established programming principles for clean code like the SRP. "You can jump anywhere" is not (and has never been) a valid argument in C++, and somehow I don't like teaching stuff that is not true. 1: Also, I have never been able to resurrect even a single velociraptor, no matter how many gotos I tried :(

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• Unit Testing Framework for XQuery

  - by Knut Vatsendvik

  This posting provides a unit testing framework for XQuery using Oracle Service Bus. It allows you to write a test case to run your XQuery transformations in an automated fashion. When the test case is run, the framework returns any differences found in the response. The complete code sample with install instructions can be downloaded from here. Writing a Unit Test You start a new Test Case by creating a Proxy Service from Workshop that comes with Oracle Service Bus. In the General Configuration page select Service Type to be Messaging Service           In the Message Type Configuration page link both the Request & Response Message Type to the TestCase element of the UnitTest.xsd schema                 The TestCase element consists of the following child elements The ID and optional Name element is simply used for reference. The Transformation element is the XQuery resource to be executed. The Input elements represents the input to run the XQuery with. The Output element represents the expected output. These XML documents are “also” represented as an XQuery resource where the XQuery function takes no arguments and returns the XML document. Why not pass the test data with the TestCase? Passing an XML structure in another XML structure is not very easy or at least not very human readable. Therefore it was chosen to represent the test data as an loadable resource in the OSB. However you are free to go ahead with another approach on this if wanted. The XMLDiff elements represents any differences found. A sample on input is shown here. Modeling the Message Flow Then the next step is to model the message flow of the Proxy Service. In the Request Pipeline create a stage node that loads the test case input data.      For this, specify a dynamic XQuery expression that evaluates at runtime to the name of a pre-registered XQuery resource. The expression is of course set by the input data from the test case.           Add a Run stage node. Assign the result of the XQuery, that is to be run, to a context variable. Define a mapping for each of the input variables added in previous stage.     Add a Compare stage. Like with the input data, load the expected output data. Do a compare using XMLDiff XQuery provided where the first argument is the loaded output test data, and the second argument the result from the Run stage. Any differences found is replaced back into the test case XMLDiff element. In case of any unexpected failure while processing, add an Error Handler to the Pipeline to capture the fault. To pass back the result add the following Insert action In the Response Pipeline. A sample on output is shown here.

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• Deploy Oracle Management Agent using RPM File

  - by cristiano.toni

  Normal 0 21 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tableau Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times","serif"; mso-ansi-language:FR;} 1) Create a rpm package on Enterprise Manager 12c a) as Root : # yum install rpmbuild # mkdir /usr/lib/oracle b) as oracle user # cd $<OMS_HOME>/bin/ # emcli get_supported_platforms ----------------------------------------------- Version = 12.1.0.3.0  Platform = Linux x86-64 ----------------------------------------------- Platforms list displayed successfully. #  emcli get_agentimage_rpm -destination=/tmp/agentRPM -platform="Linux x86-64" \ -version=12.1.0.3.0 Platform:Linux x86-64 Destination:/tmp/agentRPM Exalogic:false  Checking for disk space requirements...  === Partition Detail === Space free : 6 GB Space required : 1 GB RPM creation in progress ... Check the logs at /Oracle/gc_inst/em/EMGC_OMS1/sysman/emcli/setup/.emcli/get_agentimage_rpm_date-PM.log Copying agent image from software library to /tmp/agentRPM Setting property ORACLE_HOME to:/Oracle/middleware/oms calling pulloneoffs with arguments:/Oracle/middleware/oms/Oracle/middleware/oms/sysman/agent/ \ 12.1.0.3.0_AgentCore_226.zip12.1.0.3.0Linux x86-64/tmp/agentRPMtrue Agent Image copied successfully... Creation of RPM started... RPM creation successful. Agent image to rpm conversion completed successfully 2) Copy it on all new hosts and install it.  As Root user : c) check and install rpm file # rpm -ivh --test oracle-agt-12.1.0.3.0-1.0.x86_64.rpm  Preparing...                ########################################### [100%] # rpm -ivh oracle-agt-12.1.0.3.0-1.0.x86_64.rpm  Preparing...                ########################################### [100%] Running the prereq    1:oracle-agt             ########################################### [100%] Agent RPM installation is completed successfully. Now to configure the agent follow the below steps: 1. Edit the properties file: /usr/lib/oracle/agent/agent.properties with the correct values 2. Execute the script /etc/init.d/oracle-agt RESPONSE_FILE=/usr/lib/oracle/agent/agent.properties d) create a user for the agent: # useradd -m -d /home/em12adm -s /bin/bash -g dba -G oinstall em12adm # passwd em12adm e) Edit file /usr/lib/oracle/agent/agent.properties # vi /usr/lib/oracle/agent/agent.properties  OMS_HOST=<host_Enterprise_Manager> OMS_PORT=<HTTPS Upload Port > AGENT_REGISTRATION_PASSWORD=oracle AGENT_USERNAME=em12adm AGENT_GROUP=dba ORACLE_HOSTNAME=oraclevm-mgmt # chown -R em12adm:dba /usr/lib/oracle/agent/ Start agent and register the new host server on EM12c   #  /etc/init.d/oracle-agt RESPONSE_FILE=/usr/lib/oracle/agent/agent.properties Now you have registered on EM12C your new target host.

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• RPi and Java Embedded GPIO: Sensor Reading using Java Code

  - by hinkmond

  And, now to program the Java code for reading the fancy-schmancy static electricity sensor connected to your Raspberry Pi, here is the source code we'll use: First, we need to initialize ourselves... /* * Java Embedded Raspberry Pi GPIO Input app */ package jerpigpioinput; import java.io.FileWriter; import java.io.RandomAccessFile; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Calendar; /** * * @author hinkmond */ public class JerpiGPIOInput { static final String GPIO_IN = "in"; // Add which GPIO ports to read here static String[] GpioChannels = { "7" }; /** * @param args the command line arguments */ public static void main(String[] args) { try { /*** Init GPIO port(s) for input ***/ // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); for (String gpioChannel : GpioChannels) { System.out.println(gpioChannel); // Reset the port unexportFile.write(gpioChannel); unexportFile.flush(); // Set the port for use exportFile.write(gpioChannel); exportFile.flush(); // Open file handle to input/output direction control of port FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction"); // Set port for input directionFile.write(GPIO_IN); directionFile.flush(); } And, next we will open up a RandomAccessFile pointer to the GPIO port. /*** Read data from each GPIO port ***/ RandomAccessFile[] raf = new RandomAccessFile[GpioChannels.length]; int sleepPeriod = 10; final int MAXBUF = 256; byte[] inBytes = new byte[MAXBUF]; String inLine; int zeroCounter = 0; // Get current timestamp with Calendar() Calendar cal; DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss.SSS"); String dateStr; // Open RandomAccessFile handle to each GPIO port for (int channum=0; channum Then, loop forever to read in the values to the console. // Loop forever while (true) { // Get current timestamp for latest event cal = Calendar.getInstance(); dateStr = dateFormat.format(cal.getTime()); // Use RandomAccessFile handle to read in GPIO port value for (int channum=0; channum Rinse, lather, and repeat... Compile this Java code on your host PC or Mac with javac from the JDK. Copy over the JAR or class file to your Raspberry Pi, "sudo -i" to become root, then start up this Java app in a shell on your RPi. That's it! You should see a "1" value get logged each time you bring a statically charged item (like a balloon you rub on the cat) near the antenna of the sensor. There you go. You've just seen how Java Embedded technology on the Raspberry Pi is an easy way to access sensors. Hinkmond

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• New R Interface to Oracle Data Mining Available for Download

  - by charlie.berger

    The R Interface to Oracle Data Mining ( R-ODM) allows R users to access the power of Oracle Data Mining's in-database functions using the familiar R syntax. R-ODM provides a powerful environment for prototyping data analysis and data mining methodologies. R-ODM is especially useful for: Quick prototyping of vertical or domain-based applications where the Oracle Database supports the application Scripting of "production" data mining methodologies Customizing graphics of ODM data mining results (examples: classification, regression, anomaly detection) The R-ODM interface allows R users to mine data using Oracle Data Mining from the R programming environment. It consists of a set of function wrappers written in source R language that pass data and parameters from the R environment to the Oracle RDBMS enterprise edition as standard user PL/SQL queries via an ODBC interface. The R-ODM interface code is a thin layer of logic and SQL that calls through an ODBC interface. R-ODM does not use or expose any Oracle product code as it is completely an external interface and not part of any Oracle product. R-ODM is similar to the example scripts (e.g., the PL/SQL demo code) that illustrates the use of Oracle Data Mining, for example, how to create Data Mining models, pass arguments, retrieve results etc. R-ODM is packaged as a standard R source package and is distributed freely as part of the R environment's Comprehensive R Archive Network (CRAN). For information about the R environment, R packages and CRAN, see www.r-project.org. R-ODM is particularly intended for data analysts and statisticians familiar with R but not necessarily familiar with the Oracle database environment or PL/SQL. It is a convenient environment to rapidly experiment and prototype Data Mining models and applications. Data Mining models prototyped in the R environment can easily be deployed in their final form in the database environment, just like any other standard Oracle Data Mining model. What is R? R is a system for statistical computation and graphics. It consists of a language plus a run-time environment with graphics, a debugger, access to certain system functions, and the ability to run programs stored in script files. The design of R has been heavily influenced by two existing languages: Becker, Chambers & Wilks' S and Sussman's Scheme. Whereas the resulting language is very similar in appearance to S, the underlying implementation and semantics are derived from Scheme. R was initially written by Ross Ihaka and Robert Gentleman at the Department of Statistics of the University of Auckland in Auckland, New Zealand. Since mid-1997 there has been a core group (the "R Core Team") who can modify the R source code archive. Besides this core group many R users have contributed application code as represented in the near 1,500 publicly-available packages in the CRAN archive (which has shown exponential growth since 2001; R News Volume 8/2, October 2008). Today the R community is a vibrant and growing group of dozens of thousands of users worldwide. It is free software distributed under a GNU-style copyleft, and an official part of the GNU project ("GNU S"). Resources: R website / CRAN R-ODM

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• Responding to the page unload in a managed bean

  - by frank.nimphius

  Though ADF Faces provides an uncommitted data warning functionality, developers may have the requirement to respond to the page unload event within custom application code, programmed in a managed bean. The af:clientListener tag that is used in ADF Faces to listen for JavaScript and ADF Faces client component events does not provide the option to listen for the unload event. So this often recommended way of implementing JavaScript in ADF Faces does not work for this use case. To send an event from JavaScript to the server, ADF Faces provides the af:serverListener tag that you use to queue a CustomEvent that invokes method in a managed bean. While this is part of the solution, during testing, it turns out, the browser native JavaScript unload event itself is not very helpful to send an event to the server using the af:serverListener tag. The reason for this is that when the unload event fires, the page already has been unloaded and the ADF Faces AdfPage object needed to queue the custom event already returns null. So the solution to the unload page event handling is the unbeforeunload event, which I am not sure if all browsers support them. I tested IE and FF and obviously they do though. To register the beforeunload event, you use an advanced JavaScript programming technique that dynamically adds listeners to page events. <af:document id="d1" onunload="performUnloadEvent"                      clientComponent="true"> <af:resource type="javascript">   window.addEventListener('beforeunload',                            function (){performUnloadEvent()},false)      function performUnloadEvent(){   //note that af:document must have clientComponent="true" set   //for JavaScript to access the component object   var eventSource = AdfPage.PAGE.findComponentByAbsoluteId('d1');   //var x and y are dummy variables obviously needed to keep the page   //alive for as long it takes to send the custom event to the server   var x = AdfCustomEvent.queue(eventSource,                                "handleOnUnload",                                {args:'noargs'},false);   //replace args:'noargs' with key:value pairs if your event needs to   //pass arguments and values to the server side managed bean.   var y = 0; } </af:resource> <af:serverListener type="handleOnUnload"                    method="#{UnloadHandler.onUnloadHandler}"/> // rest of the page goes here … </af:document> The managed bean method called by the custom event has the following signature:  public void onUnloadHandler(ClientEvent clientEvent) {  } I don't really have a good explanation for why the JavaSCript variables "x" and "y" are needed, but this is how I got it working. To me it ones again shows how fragile custom JavaScript development is and why you should stay away from using it whenever possible. Note: If the unload event is produced through navigation in JavaServer Faces, then there is no need to use JavaScript for this. If you know that navigation is performed from one page to the next, then the action you want to perform can be handled in JSF directly in the context of the lifecycle.

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• Ask the Readers: Would You Be Willing to Give Windows Up and Use a Different O.S.?

  - by Asian Angel

  When it comes to computers, Windows definitely rules the desktop in comparison to other operating systems. What we would like to know this week is if you would actually be willing to give up using Windows altogether and move to a different operating system on your computers. Note: This week’s Ask the Readers post is posing a hypothetical situation, so please refrain from starting arguments or a flame war in the comments. Good reasoned discussion is always welcome. There is no doubt that Windows is the dominant operating system in use today. Everywhere you go or look it is easy to find computers with Windows installed such as at work, home, the library, government offices, and more. For many people it is the operating system that they know and are comfortable with, which makes changing to a different operating system less appealing. Adding to the preference for Windows (or dependency based on your view) is the custom software that many businesses use on a daily basis. Throw in the high volume of people who depend on and use Microsoft Office as a standard for their business documents and it is little wonder that Windows is so dominant. So what would you use if you did decide to take a break from or permanently move away from Windows? If your choice is Linux then you have a large and wonderful variety of distributions to choose from based on what you want out of your system. Want a distribution that is easy to work with? You could choose Ubuntu, Linux Mint, or others that are engineered to be ready to go “out of the box”. Like a challenge? Perhaps Arch Linux is more your style. One of the most attractive features of all about Linux is the price…it is very hard to beat free! Maybe Mac OS X sounds like the perfect choice. It has a certain mystique and elegance associated with it and many OS X fans refuse to use anything else if given a choice. Then there is the soon to be released Chrome OS with its’ emphasis on cloud computing. This is a system that is definitely focused on being as low-maintenance and hassle-free as possible. Quick on, quick off, minimalist, and made to be portable. All of the system’s updates will occur automatically leaving you free to work and play in the cloud. But it does have its’ limitations…no installing all of those custom apps that you love using on Windows or other systems…it is literally all about the browsing window and web apps. So there you have it. If the opportunity presented itself would you, could you give Windows up and use a different operating system? Would it be easy or hard for you to do? Perhaps it would not really matter so long as you could do what you needed or wanted to do on a computer. And maybe this is the perfect time to try something new and find out…that new favorite operating system could be just an install disc away. Let us know your thoughts in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor The Brothers Mario – Epic Gangland Style Mario Brothers Movie Trailer [Video] Score Awesome Games on the Cheap with the Humble Indie Bundle Add a Colorful Christmas Theme to Your Windows 7 Desktop This Windows Hack Changes the Blue Screen of Death to Red Edit Images Quickly in Firefox with Pixlr Grabber Zoho Writer, Sheet, and Show Now Available in Chrome Web Store

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• A proposal for #DAX Code Formatting #ssas #powerpivot #tabular

  - by Marco Russo (SQLBI)

  I recently published a set of rules for DAX code formatting. The following is an example of what I obtain: CALCULATE (     SUMX (         Orders,         Orders[Amount]     ),     FILTER (         ALL ( Customers ),         CALCULATE (             COUNTROWS ( Sales ),             ALL ( Calendar[Date] )         ) > 42 + 8 – 25 * ( 3 - 1 )             + 2 – 1 + 2 – 1             + CALCULATE (                   2 + 2 – 2                   + 2 - 2               )             – CALCULATE ( 4 )     ) ) The goal is to improve code readability and I look forward to implement a code formatting feature in DAX Studio. The DAX Editor already supports the rules described in the article. I am also considering whether to add a rule specific for ADDCOLUMNS / SUMMARIZE because I would like to see the “pairs” of arguments to define a column in the same row or with a special indentation rule (DAX expression for a column is indented in the line following the column name). EVALUATE CALCULATETABLE (        CALCULATETABLE (         SUMMARIZE (             Audience,             'Date'[Year],             Individuals[Gender],             Individuals[AgeRange],             "Num of Rows", FORMAT (COUNTROWS (Audience), "#,#"),             "Weighted Mean Age",                 SUMX (Audience, Audience[Weight] * Audience[Age]) / SUM (Audience[Weight])         ),         SUMMARIZE (             BridgeIndividualsTargets,             Individuals[ID_Individual]         ),         Audience[Weight] > 0        ),        Targets[Target] = "Maschi",     'Date'[Year] = 2010,     'Date'[MonthName] = "January" ) I would like to get feedback for that – you can use comments here or comments in original article. Thanks!

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• What are the disadvantages of self-encapsulation?

  - by Dave Jarvis

  Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use (dereference) uninitialized variables. In 1989, Wirfs-Brock and Wikerson wrote: Direct references to variables severely limit the ability of programmers to re?ne existing classes. The programming conventions described here structure the use of variables to promote reusable designs. We encourage users of all object-oriented languages to follow these conventions. Additionally, we strongly urge designers of object-oriented languages to consider the effects of unrestricted variable references on reusability. Problem A lot of software, especially in Java, but likely in C# and C++, often uses the following pattern: public class SomeClass { private String someAttribute; public SomeClass() { this.someAttribute = "Some Value"; } public void someMethod() { if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { return this.someAttribute; } } Sometimes a band-aid solution is used by checking for null throughout the code base: public void someMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void anotherMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Default Value" ) ) { // do something... } } The band-aid does not always avoid the null pointer problem: a race condition exists. The race condition is mitigated using: public void anotherMethod() { String someAttribute = this.someAttribute; assert someAttribute != null; if( someAttribute.equals( "Some Default Value" ) ) { // do something... } } Yet that requires two statements (assignment to local copy and check for null) every time a class-scoped variable is used to ensure it is valid. Self-Encapsulation Ken Auer's Reusability Through Self-Encapsulation (Pattern Languages of Program Design, Addison Wesley, New York, pp. 505-516, 1994) advocated self-encapsulation combined with lazy initialization. The result, in Java, would resemble: public class SomeClass { private String someAttribute; public SomeClass() { setAttribute( "Some Value" ); } public void someMethod() { if( getAttribute().equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { String someAttribute = this.someAttribute; if( someAttribute == null ) { setAttribute( createDefaultValue() ); } return someAttribute; } protected String createDefaultValue() { return "Some Default Value"; } } All duplicate checks for null are superfluous: getAttribute() ensures the value is never null at a single location within the containing class. Efficiency arguments should be fairly moot -- modern compilers and virtual machines can inline the code when possible. As long as variables are never referenced directly, this also allows for proper application of the Open-Closed Principle. Question What are the disadvantages of self-encapsulation, if any? (Ideally, I would like to see references to studies that contrast the robustness of similarly complex systems that use and don't use self-encapsulation, as this strikes me as a fairly straightforward testable hypothesis.)

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• How to define template directives (from an API perspective)?

  - by Ralph

  Preface I'm writing a template language (don't bother trying to talk me out of it), and in it, there are two kinds of user-extensible nodes. TemplateTags and TemplateDirectives. A TemplateTag closely relates to an HTML tag -- it might look something like div(class="green") { "content" } And it'll be rendered as <div class="green">content</div> i.e., it takes a bunch of attributes, plus some content, and spits out some HTML. TemplateDirectives are a little more complicated. They can be things like for loops, ifs, includes, and other such things. They look a lot like a TemplateTag, but they need to be processed differently. For example, @for($i in $items) { div(class="green") { $i } } Would loop over $items and output the content with the variable $i substituted in each time. So.... I'm trying to decide on a way to define these directives now. Template Tags The TemplateTags are pretty easy to write. They look something like this: [TemplateTag] static string div(string content = null, object attrs = null) { return HtmlTag("div", content, attrs); } Where content gets the stuff between the curly braces (pre-rendered if there are variables in it and such), and attrs is either a Dictionary<string,object> of attributes, or an anonymous type used like a dictionary. It just returns the HTML which gets plunked into its place. Simple! You can write tags in basically 1 line. Template Directives The way I've defined them now looks like this: [TemplateDirective] static string @for(string @params, string content) { var tokens = Regex.Split(@params, @"\sin\s").Select(s => s.Trim()).ToArray(); string itemName = tokens[0].Substring(1); string enumName = tokens[1].Substring(1); var enumerable = data[enumName] as IEnumerable; var sb = new StringBuilder(); var template = new Template(content); foreach (var item in enumerable) { var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; sb.Append(template.Render(templateVars)); } return sb.ToString(); } (Working example). Basically, the stuff between the ( and ) is not split into arguments automatically (like the template tags do), and the content isn't pre-rendered either. The reason it isn't pre-rendered is because you might want to add or remove some template variables or something first. In this case, we add the $i variable to the template variables, var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; And then render the content manually, sb.Append(template.Render(templateVars)); Question I'm wondering if this is the best approach to defining custom Template Directives. I want to make it as easy as possible. What if the user doesn't know how to render templates, or doesn't know that he's supposed to? Maybe I should pass in a Template instance pre-filled with the content instead? Or maybe only let him tamper w/ the template variables, and then automatically render the content at the end? OTOH, for things like "if" if the condition fails, then the template wouldn't need to be rendered at all. So there's a lot of flexibility I need to allow in here. Thoughts?

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• Where should you put constants and why?

  - by Tim Meyer

  In our mostly large applications, we usually have a only few locations for constants: One class for GUI and internal contstants (Tab Page titles, Group Box titles, calculation factors, enumerations) One class for database tables and columns (this part is generated code) plus readable names for them (manually assigned) One class for application messages (logging, message boxes etc) The constants are usually separated into different structs in those classes. In our C++ applications, the constants are only defined in the .h file and the values are assigned in the .cpp file. One of the advantages is that all strings etc are in one central place and everybody knows where to find them when something must be changed. This is especially something project managers seem to like as people come and go and this way everybody can change such trivial things without having to dig into the application's structure. Also, you can easily change the title of similar Group Boxes / Tab Pages etc at once. Another aspect is that you can just print that class and give it to a non-programmer who can check if the captions are intuitive, and if messages to the user are too detailed or too confusing etc. However, I see certain disadvantages: Every single class is tightly coupled to the constants classes Adding/Removing/Renaming/Moving a constant requires recompilation of at least 90% of the application (Note: Changing the value doesn't, at least for C++). In one of our C++ projects with 1500 classes, this means around 7 minutes of compilation time (using precompiled headers; without them it's around 50 minutes) plus around 10 minutes of linking against certain static libraries. Building a speed optimized release through the Visual Studio Compiler takes up to 3 hours. I don't know if the huge amount of class relations is the source but it might as well be. You get driven into temporarily hard-coding strings straight into code because you want to test something very quickly and don't want to wait 15 minutes just for that test (and probably every subsequent one). Everybody knows what happens to the "I will fix that later"-thoughts. Reusing a class in another project isn't always that easy (mainly due to other tight couplings, but the constants handling doesn't make it easier.) Where would you store constants like that? Also what arguments would you bring in order to convince your project manager that there are better concepts which also comply with the advantages listed above? Feel free to give a C++-specific or independent answer. PS: I know this question is kind of subjective but I honestly don't know of any better place than this site for this kind of question. Update on this project I have news on the compile time thing: Following Caleb's and gbjbaanb's posts, I split my constants file into several other files when I had time. I also eventually split my project into several libraries which was now possible much easier. Compiling this in release mode showed that the auto-generated file which contains the database definitions (table, column names and more - more than 8000 symbols) and builds up certain hashes caused the huge compile times in release mode. Deactivating MSVC's optimizer for the library which contains the DB constants now allowed us to reduce the total compile time of your Project (several applications) in release mode from up to 8 hours to less than one hour! We have yet to find out why MSVC has such a hard time optimizing these files, but for now this change relieves a lot of pressure as we no longer have to rely on nightly builds only. That fact - and other benefits, such as less tight coupling, better reuseability etc - also showed that spending time splitting up the "constants" wasn't such a bad idea after all ;-)

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• Caching factory design

  - by max

  I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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• Problem with creating a deterministic finite automata (DFA) - Mercury

  - by Jabba The hut

  I would like to have a deterministic finite automata (DFA) simulated in Mercury. But I’m s(t)uck at several places. Formally, a DFA is described with the following characteristics: a setOfStates S, an inputAlphabet E <-- summation symbol, a transitionFunction : S × E -- S, a startState s € S, a setOfAcceptableFinalStates F =C S. A DFA will always starts in the start state. Then the DFA will read all the characters on the input, one by one. Based on the current input character and the current state, there will be made to a new state. These transitions are defined in the transitions function. when the DFA is in one of his acceptable final states, after reading the last character, then will the DFA accept the input, If not, then the input will be is rejected. The figure shows a DFA the accepting strings where the amount of zeros, is a plurality of three. Condition 1 is the initial state, and also the only acceptable state. for each input character is the corresponding arc followed to the next state. Link to Figure What must be done A type “mystate” which represents a state. Each state has a number which is used for identification. A type “transition” that represents a possible transition between states. Each transition has a source_state, an input_character, and a final_state. A type “statemachine” that represents the entire DFA. In the solution, the DFA must have the following properties: The set of all states, the input alphabet, a transition function, represented as a set of possible transitions, a set of accepting final states, a current state of the DFA A predicate “init_machine (state machine :: out)” which unifies his arguments with the DFA, as shown as in the Figure. The current state for the DFA is set to his initial state, namely, 1. The input alphabet of the DFA is composed of the characters '0'and '1'. A user can enter a text, which will be controlled by the DFA. the program will continues until the user types Ctrl-D and simulates an EOF. If the user use characters that are not allowed into the input alphabet of the DFA, then there will be an error message end the program will close. (pred require) Example Enter a sentence: 0110 String is not ok! Enter a sentence: 011101 String is not ok! Enter a sentence: 110100 String is ok! Enter a sentence: 000110010 String is ok! Enter a sentence: 011102 Uncaught exception Mercury: Software Error: Character does not belong to the input alphabet! the thing wat I have. :- module dfa. :- interface. :- import_module io. :- pred main(io.state::di, io.state::uo) is det. :- implementation. :- import_module int,string,list,bool. 1 :- type mystate ---> state(int). 2 :- type transition ---> trans(source_state::mystate, input_character::bool, final_state::mystate). 3 (error, finale_state and current_state and input_character) :- type statemachine ---> dfa(list(mystate),list(input_character),list(transition),list(final_state),current_state(mystate)) 4 missing a lot :- pred init_machine(statemachine :: out) is det. %init_machine(statemachine(L_Mystate,0,L_transition,L_final_state,1)) :- <-probably fault 5 not perfect main(!IO) :- io.write_string("\nEnter a sentence: ", !IO), io.read_line_as_string(Input, !IO), ( Invoer = ok(StringVar), S1 = string.strip(StringVar), (if S1 = "mustbeabool" then io.write_string("Sentenceis Ok! ", !IO) else io.write_string("Sentence is not Ok!.", !IO)), main(!IO) ; Invoer = eof ; Invoer = error(ErrorCode), io.format("%s\n", [s(io.error_message(ErrorCode))], !IO) ). Hope you can help me kind regards

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• C# 5 Async, Part 3: Preparing Existing code For Await

  - by Reed

  While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .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; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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• Incentivizing Work with Development Teams

  - by MarkPearl

  Recently I saw someone on twitter asking about incentives and if anyone had past experience with incentivizing work. I promised to respond with some of the experiences I have had in the past so here goes... **Disclaimer** - these are my experiences with incentives, generally in software development - in some other industries this may not be applicable – this is also my thinking at this point in time, with more experience my opinion may change. Incentivize at the level that you want people to group at If you are wanting to promote a team mentality, incentivize teams. If you want to promote an individual mentality, incentivize individuals. There is nothing worse than mixing this up. Some organizations put a lot of effort in establishing teams and team mentalities but reward individuals. This has a counter effect on the resources they have put towards establishing a team mentality. In the software projects that I work with we want promote cross functional teams that collaborate. Personally, if I was on a team and knew that there was an opportunity to work on a critical component of the system, and that by doing so I would get a bigger bonus, then I would be hesitant to include other people in solving that problem. Thus, I would hinder the teams efforts in being cross functional and reduce collaboration levels. Does that mean everyone in the team should get an even share of an incentive? In most situations I would say yes - even though this may feel counter-intuitive. I have heard arguments put forward that if “person x contributed more than person Y then they should be rewarded more” – This may sound controversial but I would rather treat people how would you like them to perform, not where they currently are at. To add to this approach, if someone is free loading, you bet your bottom dollar that the team is going to make this a lot more transparent if they feel that individual is going to be rewarded at the same level that everyone else is. Bad incentives promote destructive work If you are going to incentivize people, pick you incentives very carefully. I had an experience once with a sales person who was told they would get a bonus provided that they met an ordering target with a particular supplier. What did this person do? They sold everything at cost for the next month or so. They reached the goal, but the company didn't gain anything from it. It was a bad incentive. Expect the same with development teams, if you incentivize zero bug levels, you will get zero code committed to the solution. If you incentivize lines of code, you will get many many lines of bad code. Is there such a thing as a good incentives? Monetary wise, I am not sure there is. I would much rather encourage organizations to pay their people what they are worth upfront. I would also advise against paying money to teams as an incentive or even a bonus or reward for reaching a milestone. Rather have a breakaway for the team that promotes team building as a reward if they reach a milestone than pay them more money. I would also advise against making the incentive the reason for them to reach the milestone. If this becomes the norm it promotes people to begin to only do their job if there is an incentive at the end of the line. This is not a behaviour one wants to encourage. If the team or individual is in the right mind-set, they should not work any harder than they are right now with normal pay.

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• Violation of the DRY Principle

  - by Onorio Catenacci

  I am sure there's a name for this anti-pattern somewhere; however I am not familiar enough with the anti-pattern literature to know it. Consider the following scenario: or0 is a member function in a class. For better or worse, it's heavily dependent on class member variables. Programmer A comes along and needs functionality like or0 but rather than calling or0, Programmer A copies and renames the entire class. I'm guessing that she doesn't call or0 because, as I say, it's heavily dependent on member variables for its functionality. Or maybe she's a junior programmer and doesn't know how to call it from other code. So now we've got or0 and c0 (c for copy). I can't completely fault Programmer A for this approach--we all get under tight deadlines and we hack code to get work done. Several programmers maintain or0 so it's now version orN. c0 is now version cN. Unfortunately most of the programmers that maintained the class containing or0 seemed to be completely unaware of c0--which is one of the strongest arguments I can think of for the wisdom of the DRY principle. And there may also have been independent maintainance of the code in c. Either way it appears that or0 and c0 were maintained independent of each other. And, joy and happiness, an error is occurring in cN that does not occur in orN. So I have a few questions: 1.) Is there a name for this anti-pattern? I've seen this happen so often I'd find it hard to believe this is not a named anti-pattern. 2.) I can see a few alternatives: a.) Fix orN to take a parameter that specifies the values of all the member variables it needs. Then modify cN to call orN with all of the needed parameters passed in. b.) Try to manually port fixes from orN to cN. (Mind you I don't want to do this but it is a realistic possibility.) c.) Recopy orN to cN--again, yuck but I list it for sake of completeness. d.) Try to figure out where cN is broken and then repair it independently of orN. Alternative a seems like the best fix in the long term but I doubt the customer will let me implement it. Never time or money to fix things right but always time and money to repair the same problem 40 or 50 times, right? Can anyone suggest other approaches I may not have considered? If you were in my place, which approach would you take? If there are other questions and answers here along these lines, please post links to them. I don't mind removing this question if it's a dupe but my searching hasn't turned up anything that addresses this question yet. EDIT: Thanks everyone for all the thoughtful responses. I asked about a name for the anti-pattern so I could research it further on my own. I'm surprised this particular bad coding practice doesn't seem to have a "canonical" name for it.

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• Can you/should you develop components for ASP.NET MVC?

  - by Vilx-

  Following from the previous question I've started to wonder - is it possible to implement "Components" in ASP.NET MVC (latest version)? And should you? Let's clarify what I mean with a "component". With that I mean a "control" (aka "widget"), similar to those that ASP.NET webforms is built upon. A gridview might be a good example. In webforms I can place on my form a datasource component (one line of code), a gridview component (another line of code) and bind them together (specify an attribute on the gridview). In the codebehind file I fill the datasource with data (a few lines of DB-querying code), and I'm all set. At this point the gridview is a fully functional standalone component. I can open the form, and I'll see all the data. I can sort it by clicking on the column headers; it is split into several pages; I can drag the column headers around and rearrange columns; I can turn on "grouping" mode; etc. And I don't need to write another line of code for any of it. The gridview, as a component, already has all the code tucked away in its classes and assemblies. I just place it on the form, initialize it, and it Just Works. At some times (like sorting or navigation to a different page) it will also perform ajax callbacks to the server, but those too will be handled internally, with my code having no knowledge at all about it. And then there are also events that I can attach if I want to get notified when something happens. In MVC I cannot see a way of doing this cleanly. Sure, there are the partial views, but those only handle half of the problem - they render the initial HTML. Some more can be achieved with client-side Javascript (like column re-arranging), but when the grid needs to do an ajax callback (say, to fetch the next page of data), my code will have to get involved and process that request. At best I guess I can provide some helper methods to process it, but I'll have to write the code that calls them, and also provide a controller method with signature matching the arguments of that callback. I guess that I could make some hacks with global events or special routes or something, but that just seems... hackish. Unelegant. Perhaps this is not the MVC way? Although I've completed one project in it, I'm still far from being an MVC expert. But then what is? In the intranet application that we're building there are dozens upon dozens of such grids. Naturally I want them all to have a unified look & behavior, and I don't want to repeat the same code all over the place. So what's the "MVC" approach to this problem?

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