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  • Designing complex query builders in java/jpa/hibernate

    - by Ramraj Edagutti
    I need to build complex sql queries programatically, based on large filter conditions. For example, below are few sample/hypothitical filter conditions, based on which i need to fetch users Country: india States: Andhra Pradesh(AP), Gujarat(GUJ), karnataka(KTK) Districts: All districts in AP except 3 district, 5 any districts from GUJ, all district from KTK except 1 district Cities: All cities in AP, all cities except few, include only 50 specific cities from KTK Villages: similar conditions like above with varies combinations... Currently, we have a query builder, which is very complex in nature, and not easy to modify/re-factory for improvements. So, thinking of complete re-design of it. Any suggesations on how to build this kind of complex query builders programmatically using some best practices/deisgn patterns?

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  • Modelling highly specific business requirements

    - by AndyBursh
    How can one go about modelling highly specific business requirements, which have no precedent in the system? Take for example the following requirement: When a purchase order contains N lines, is over X value in total and is being recorded against project Y, an email needs to be sent to persons A and B with the details This requirement supplements other requirements surrounding purchase orders, but comes in at a much later date in response to some ongoing problem elsewhere in the business. Persons A and B are not part of any role or group in the system, and don't hold any specific responsibility; they are simply the two people the business has appointed to receive these emails in this very specific case. Projects are also data driven, so project Y has no special properties to distinguish it from any other project. The only way to identify it is to compare its identifier to a magic number. How can one go about modelling this kind of case without introducing too much additional complexity? That I can think of right now, there are a couple of options. Perform the checks and actions inline with the existing code. Here we find the correct spot in the code, check the conditions in the requirement and send the emails to hardcoded addresses. Of course this is fraught with issues. At the very least it stops working if one of these people leaves or changes their email address. At worst you have to ensure that any tests and test data are aware that additional actions are taken for a specific set of criteria. Introduce some form of events system. Here we introduce an eventing system, so that we might react to some event, and fulfil the requirement outside of the usual path of execution. This sounds like a cleaner solution than option 1, but the work involved is ultimately probably slightly overkill for this one small requirement. That said, having it in place does allow the system to handle these kinds of specific requirements consistently and easily in the future. Are there any other (good/better) ways of handling highly specific requirements? I mean other than telling the other parts of the business no!

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  • Building general programming skills?

    - by toleero
    I currently am quite new to programming, I've had exposure to a few languages (C#, PHP, JavaScript, VB, and some others) and I'm quite new to OOP. I was just wondering what is the best way to build up general programming/problem solving skills without being language specific? I was thinking maybe of something like Project Euler but more geared towards newbies? Thanks! Edit: I am looking at getting into Game Scripting/Programming, I'm already in Games but in a different discipline :)

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  • Avoid Postfix Increment Operator

    - by muntoo
    I've read that I should avoid the postfix increment operator because of performance reasons (in certain cases). But doesn't this affect code readability? In my opinion: for(int i = 0; i < 42; i++); /* i will never equal 42! */ Looks better than: for(int i = 0; i < 42; ++i); /* i will never equal 42! */ But this is probably just out of habit. Admittedly, I haven't seen many use ++i. Is the performance that bad to sacrifice readability, in this case? Or am I just blind, and ++i is more readable than i++?

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  • Kinect office demo ideas

    - by Tedd Hansen
    I'm thinking of placing a Kinect (connected to a PC) in the office and have something fun on it. Just a small thing people can interact with. Basically I get a depthmap (image) and a color image from the Kinect which I can analyze and do stuff with. My limited imagination came up with: Count people passing by. Measure average width of people passing by. Some ball with physics people can play with. Audible alert when someone is walking too fast. Anyone have any good ideas? :)

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  • As a tooling/automation developer, can I be making better use of OOP?

    - by Tom Pickles
    My time as a developer (~8 yrs) has been spent creating tooling/automation of one sort or another. The tools I develop usually interface with one or more API's. These API's could be win32, WMI, VMWare, a help-desk application, LDAP, you get the picture. The apps I develop could be just to pull back data and store/report. It could be to provision groups of VM's to create live like mock environments, update a trouble ticket etc. I've been developing in .Net and I'm currently reading into design patterns and trying to think about how I can improve my skills to make better use of and increase my understanding of OOP. For example, I've never used an interface of my own making in anger (which is probably not a good thing), because I honestly cannot identify where using one would benefit later on when modifying my code. My classes are usually very specific and I don't create similar classes with similar properties/methods which could use a common interface (like perhaps a car dealership or shop application might). I generally use an n-tier approach to my apps, having a presentation layer, a business logic/manager layer which interfaces with layer(s) that make calls to the API's I'm working with. My business entities are always just method-less container objects, which I populate with data and pass back and forth between my API interfacing layer using static methods to proxy/validate between the front and the back end. My code by nature of my work, has few common components, at least from what I can see. So I'm struggling to see how I can better make use of OOP design and perhaps reusable patterns. Am I right to be concerned that I could be being smarter about how I work, or is what I'm doing now right for my line of work? Or, am I missing something fundamental in OOP? EDIT: Here is some basic code to show how my mgr and api facing layers work. I use static classes as they do not persist any data, only facilitate moving it between layers. public static class MgrClass { public static bool PowerOnVM(string VMName) { // Perform logic to validate or apply biz logic // call APIClass to do the work return APIClass.PowerOnVM(VMName); } } public static class APIClass { public static bool PowerOnVM(string VMName) { // Calls to 3rd party API to power on a virtual machine // returns true or false if was successful for example } }

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  • What is your most unusual javascript concept you've ever seen ?

    - by Cybrix
    Hi, I've learned javascript at school but since I'm working with it and study about it every day, I've found very particular aspect of javascript that I didn't know about. Which at first, was very hard to understand for me and finally, I found it very usefull and easy to implement. And in the final, it gives to my code some kind of "beauty". An example I've once seen: function getter( input ) { result = { foo1 : 'bar1', foo2 : 'bar2', foo3 : 'bar3' }[input] || input || "default"; return result; } Do you guys have other examples of particular use you make of Javascript ? Thank you PS: I use the term particular use because it might be unusual for any Javascript beginner. I believe this question is most likely to belong to the community wiki.

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  • Should I use JavaFx properties?

    - by Mike G
    I'm usually very careful to keep my Model, View, and Controller code separate. The thing is JavaFx properties are so convenient to bind them all together. The issue is that it makes my entire code design dependent on JavaFx, which I feel I should not being doing. I should be able to change the view without changing too much of the model and controller. So should I ignore the convenience of JavaFx properties, or should I embrace them and the fact that it reduces my codes flexibility.

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  • Mounting of UDF Bluray in Linux Mint 17

    - by user134885
    I am running Linux mint 17 Cinnamon 64 Bit 2.2.13 - 3.13.0-27 Kernal My machine is a Clevo - fitted with a bluray burner I have tried the following line sudo mount -t udf /dev/scd0 /media/bluray /dev/sr0 But to no avail. Can anyone help me with how to initiate / mount a Bluray on my machine? Thank you to anyone who can give me feedback may sanity and get it going - all works well in windows, but nothing in Linux?

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  • Inspecting the model in a Rails application

    - by Matt Sherman
    I am learning some Ruby on Rails, and am a newbie. Most of my background is in ASP.net MVC on the back end. As I play with a basic scaffold project, I wonder about this case: you jump into an established Rails project and want to get to know the model. Based on what I have seen so far (again, simple scaffold), the properties for a given class are not immediately revealed. I don't see property accessors on the model classes. I do understand that this is because of the dynamic nature of Ruby and such things are not necessary or even perhaps desirable. Convention over code, I get that. (Am familiar with dynamic concepts, mostly via JS.) But if I am somewhere off in a view, and want to quickly know whether the (eg) Person object has a MiddleName property, how would I find that out? I don't have to go into the migrations, do I?

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  • Frontend development, where to start?

    - by glitch
    I've been stuck on the backend for years now, working on webservices, DBs, SDKs, APIs and all that jazz, and so that's an area that I have a decent grasp of, but I've absolutely no clue about how the frontend works. What's a good place to start for a backend monkey like me who wants to learn the best practices, latest technologies and the philosophy behind modern web page design and its interaction with the server? I want to be cool like all of the other javascript kids. Thanks!

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  • Future-proofing myself when learning to program.

    - by Chris Bridgett
    I want to learn to program in a 'future-proof' manner, if you like. Whilst Windows dominates the desktop OS marketplace (for now), obviously there is a lot of value in learning its languages/frameworks/API's and so on - this might be subject to change as new devices emerge or Windows shoots itself in the foot (over-friendly previews of Windows 8 don't look too appealing...). Would I be right in thinking that having a solid knowledge of C/C++ for back-end logic/low level programming and the like, combined with an extremely portable language like Java for GUI's and so on, would be a good basis for software development that will prove useful on the most amount of systems? - I'm talking desktop PC's, tablets, phones.

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  • Scheme vs Haskell for an Introduction to Functional Programming?

    - by haziz
    I am comfortable with programming in C and C#, and will explore C++ in the future. I may be interested in exploring functional programming as a different programming paradigm. I am doing this for fun, my job does not involve computer programming, and am somewhat inspired by the use of functional programming, taught fairly early, in computer science courses in college. Lambda calculus is certainly beyond my mathematical abilities, but I think I can handle functional programming. Which of Haskell or Scheme would serve as a good intro to functional programming? I use emacs as my text editor and would like to be able to configure it more easily in the future which would entail learning Emacs Lisp. My understanding, however, is that Emacs Lisp is fairly different from Scheme and is also more procedural as opposed to functional. I would likely be using "The Little Schemer" book, which I have already bought, if I pursue Scheme (seems to me a little weird from my limited leafing through it). Or would use the "Learn You a Haskell for Great Good" if I pursue Haskell. I would also watch the Intro to Haskell videos by Dr Erik Meijer on Channel 9. Any suggestions, feedback or input appreciated. Thanks. P.S. BTW I also have access to F# since I have Visual Studio 2010 which I use for C# development, but I don't think that should be my main criteria for selecting a language.

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  • Nested entities in Google App Engine. Do I do it right?

    - by Aleksandr Makov
    Trying to make most of the GAE Datastore entities concept, but some doubts drill my head. Say I have the model: class User(ndb.Model): email = ndb.StringProperty(indexed=True) password = ndb.StringProperty(indexed=False) first_name = ndb.StringProperty(indexed=False) last_name = ndb.StringProperty(indexed=False) created_at = ndb.DateTimeProperty(auto_now_add=True) @classmethod def key(cls, email): return ndb.Key(User, email) @classmethod def Add(cls, email, password, first_name, last_name): user = User(parent=cls.key(email), email=email, password=password, first_name=first_name, last_name=last_name) user.put() UserLogin.Record(email) class UserLogin(ndb.Model): time = ndb.DateTimeProperty(auto_now_add=True) @classmethod def Record(cls, user_email): login = UserLogin(parent=User.key(user_email)) login.put() And I need to keep track of times of successful login operations. Each time user logs in, an UserLogin.Record() method will be executed. Now the question — do I make it right? Thanks. EDIT 2 Ok, used the typed arguments, but then it raised this: Expected Key instance, got User(key=Key('User', 5418393301680128), created_at=datetime.datetime(2013, 6, 27, 10, 12, 25, 479928), email=u'[email protected]', first_name=u'First', last_name=u'Last', password=u'password'). It's clear to understand, but I don't get why the docs are misleading? They implicitly propose to use: # Set Employee as Address entity's parent directly... address = Address(parent=employee) But Model expects key. And what's worse the parent=user.key() swears that key() isn't callable. And I found out the user.key works. EDIT 1 After reading the example form the docs and trying to replicate it — I got type error: TypeError('Model constructor takes no positional arguments.'). This is the exacto code used: user = User('[email protected]', 'password', 'First', 'Last') user.put() stamp = UserLogin(parent=user) stamp.put() I understand that Model was given the wrong argument, BUT why it's in the docs?

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  • Where do you put scenarios on a scrum board?

    - by user1043825
    So traditional scrum board looks something like this Backlog | Story notStarted inprogress Done story 1 Story1 tasks Story 2 Story2 tasks Story .. Story n Epic x Epic x+1 However in general a story has many scenarios and when working with BDD you want to write each scenario for a story as Given, when and then. Also the scenarios don't belong in the notstarted column, inprogess or Done as a scenario is not a task. So you realize that a scenario/s should have their own column between "story" and "notstarted", as a scenario can have many task to be considered done. If you are going to build your task from scenarios then why would you need the story on the scrum board in the first place, maybe they should be left in the backlog. Some people put scenarios on the back of each story. This is a on going debate in my team and I wanted to see if anyone has solved this differently. Cheers!

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  • Real performance of node.js

    - by uther.lightbringer
    I've got a question concerning node.js performance. There is quite lot of "benchmarks" and a lot of fuss about great performance of node.js. But how does it stand in real world? Not just process empty request at high speed. If someone could try to compare this scenario: Java (or equivalent) server running an application with complex business logic between receiving request and sending response. How would node.js deal with it? If there was need for a lot of JavaScript processing on server side, is node.js really so fast that it can execute JavaScript, and stand a chance against more heavyveight competitors?

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  • Producer-consumer pattern with consumer restrictions

    - by Dan
    I have a processing problem that I am thinking is a classic producer-consumer problem with the two added wrinkles that there may be a variable number of producers and there is the restriction that no more than one item per producer may be consumed at any one time. I will generally have 50-100 producers and as many consumers as CPU cores on the server. I want to maximize the throughput of the consumers while ensuring that there are never more than one work item in process from any single producer. This is more complicated than the classic producer-consumer problem which I think assumes a single producer and no restriction on which work items may be in progress at any one time. I think the problem of multiple producers is relatively easily solved by enqueuing all work items on a single work queue protected by a critical section. I think the restriction on simultaneously processing work items from any single producer is harder because I cannot think of any solution that does not require each consumer to notify some kind of work dispatcher that a particular work item has been completed so as to lift the restriction on work items from that producer. In other words, if Consumer2 has just completed WorkItem42 from Producer53, there needs to be some kind of callback or notification from Consumer2 to a work dispatcher to allow the work dispatcher to release the next work item from Producer53 to the next available consumer (whether Consumer2 or otherwise). Am I overlooking something simple here? Is there a known pattern for this problem? I would appreciate any pointers.

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  • Alternative way of developing for ASP.NET to WebForms - Any problems with this?

    - by John
    So I have been developing in ASP.NET WebForms for some time now but often get annoyed with all the overhead (like ViewState and all the JavaScript it generates), and the way WebForms takes over a lot of the HTML generation. Sometimes I just want full control over the markup and produce efficient HTML of my own so I have been experimenting with what I like to call HtmlForms. Essentially this is using ASP.NET WebForms but without the form runat="server" tag. Without this tag, ASP.NET does not seem to add anything to the page at all. From some basic tests it seems that it runs well and you still have the ability to use code-behind pages, and many ASP.NET controls such as repeaters. Of course without the form runat="server" many controls won't work. A post at Enterprise Software Development lists the controls that do require the tag. From that list you will see that all of the form elements like TextBoxes, DropDownLists, RadioButtons, etc cannot be used. Instead you use normal HTML form controls. But how do you access these HTML controls from the code behind? Retrieving values on post back is easy, you just use Request.QueryString or Request.Form. But passing data to the control could be a little messy. Do you use a ASP.NET Literal control in the value field or do you use <%= value % in the markup page? I found it best to add runat="server" to my HTML controls and then you can access the control in your code-behind like this: ((HtmlInputText)txtName).Value = "blah"; Here's a example that shows what you can do with a textbox and drop down list: Default.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form action="" method="post"> <label for="txtName">Name:</label> <input id="txtName" name="txtName" runat="server" /><br /> <label for="ddlState">State:</label> <select id="ddlState" name="ddlState" runat="server"> <option value=""></option> </select><br /> <input type="submit" value="Submit" /> </form> </body> </html> Default.aspx.cs using System; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; namespace NoForm { public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //Default values string name = string.Empty; string state = string.Empty; if (Request.RequestType == "POST") { //If form submitted (post back) name = Request.Form["txtName"]; state = Request.Form["ddlState"]; //Server side form validation would go here //and actions to process form and redirect } ((HtmlInputText)txtName).Value = name; ((HtmlSelect)ddlState).Items.Add(new ListItem("ACT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NSW")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("QLD")); ((HtmlSelect)ddlState).Items.Add(new ListItem("SA")); ((HtmlSelect)ddlState).Items.Add(new ListItem("TAS")); ((HtmlSelect)ddlState).Items.Add(new ListItem("VIC")); ((HtmlSelect)ddlState).Items.Add(new ListItem("WA")); if (((HtmlSelect)ddlState).Items.FindByValue(state) != null) ((HtmlSelect)ddlState).Value = state; } } } As you can see, you have similar functionality to ASP.NET server controls but more control over the final markup, and less overhead like ViewState and all the JavaScript ASP.NET adds. Interestingly you can also use HttpPostedFile to handle file uploads using your own input type="file" control (and necessary form enctype="multipart/form-data"). So my question is can you see any problems with this method, and any thoughts on it's usefulness? I have further details and tests on my blog.

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  • Why use sealed instead of static on a class?

    - by sq33G
    Our system has several utility classes. Some people on our team use (A) a class with all-static methods and a private constructor. Others use (B) a class with all-static methods (these the juniors). On code analysis, (A) and (B) raise warning CA1052, which recommends marking the class as sealed. Included in the MSDN documentation there is the following advice: If you are targeting .NET Framework 2.0 or earlier, a better approach is to mark the type as static. Why does this make any sense? I would have thought the opposite; AFAIK, previous to 2.0 there was no way to mark a class as static.

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  • Should I incorporate exit cost into choosing a solution

    - by Mr Happy
    I'm currently choosing between two viable software designs/solutions. Solution 1 is easy to implement, but will lock some data in a propriaty format, and will be hard to change later. Solution 2 is hard to implement, but will be a lot easier to change later on. Should I go YAGNI on this or should I incorporate the exit cost in the decision making? Or asked differently, is the exit cost part of the TCO? I'm thinking of going back to the customer with this to ask wether or not he thinks the exit costs are relevant, but I'd like to know what the community thinks first. P.S. Is exit cost the correct term?

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  • What if I can't make my unit test fail in "Red, Green, Refactor" of TDD?

    - by Joshua Harris
    So let's say that I have a test: @Test public void MoveY_MoveZero_DoesNotMove() { Point p = new Point(50.0, 50.0); p.MoveY(0.0); Assert.assertAreEqual(50.0, p.Y); } This test then causes me to create the class Point: public class Point { double X; double Y; public void MoveY(double yDisplace) { throw new NotYetImplementedException(); } } Ok. It fails. Good. Then I remove the exception and I get green. Great, but of course I need to test if it changes value. So I write a test that calls p.MoveY(10.0) and checks if p.Y is equal to 60.0. It fails, so then I change the function to look like so: public void MoveY(double yDisplace) { Y += yDisplace; } Great, now I have green again and I can move on. I've tested not moving and moving in the positive direction, so naturally I should test a negative value. The only problem with this test is that if I wrote the test correctly, then it doesn't fail at first. That means that I didn't fit the principle of "Red, Green, Refactor." Of course, This is a first-world problem of TDD, but getting a fail at first is helpful in that it shows that your test can fail. Otherwise this seemingly innocent test that is just passing for incorrect reasons could fail later because it was written wrong. That might not be a problem if it happened 5 minutes later, but what if it happens to the poor-sap that inheirited your code two years later. What he knows is that MoveY does not work with negative values because that is what the test is telling him. But, it really could work and just be a bug in the test. I don't think that would happen in this particular case because the code sample is so simple, but if it were a large complicated system that might not be the case. It seems crazy to say that I want to fail my tests, but that is an important step in TDD, for good reasons.

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  • Unit test: How best to provide an XML input?

    - by TheSilverBullet
    I need to write a unit test which validates the serialization of two attributes of an XML(size ~ 30 KB) file. What is the best way to provide an input for this test? Here are the options I have considered: Add the file to the project and use a file reader Pass the contents of the XML as a string Create the XML through a program and pass it Which is my best option and why? If there is another way which you think is better, I would love to hear it.

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  • Different ways of solving problems in code.

    - by Erin
    I now program in C# for a living but before that I programmed in python for 5 years. I have found that I write C# very differently than most examples I see on the web. Rather then writing things like: foreach (string bar in foo) { //bar has something doen to it here } I write code that looks like this. foo.ForEach( c => c.someActionhere() ) Or var result = foo.Select( c => { //Some code here to transform the item. }).ToList(); I think my using code like above came from my love of map and reduce in python - while not exactly the same thing, the concepts are close. Now it's time for my question. What concepts do you take and move with you from language to language; that allow you to solve a problem in a way that is not the normal accepted solution in that language?

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  • Using an open source non-free license

    - by wagglepoons
    Are there any projects/products out there that use an open source license that basically says "free for small companies" and "cost money for larger companies" in addition to "make modifications available"? (And are there any standard licenses with such a wording?) If I were to release a project under such a license, would it be automatically shunned by every developer on the face of the earth, or, assuming it is actually a useful project, does it have a fair chance at getting contributions from Joe Programmer? The second part of this question can easily become subjective, but any well argued point of view will be highly appreciated. For example, do dual licensed projects made by commercial entities have success with the open source communities?

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  • How useful are Lisp macros?

    - by compman
    Common Lisp allows you to write macros that do whatever source transformation you want. Scheme gives you a hygienic pattern-matching system that lets you perform transformations as well. How useful are macros in practice? Paul Graham said in Beating the Averages that: The source code of the Viaweb editor was probably about 20-25% macros. What sorts of things do people actually end up doing with macros?

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