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  • Generalise variable usage inside code

    - by Shirish11
    I would like to know if it is a good practice to generalize variables (use single variable to store all the values). Consider simple example Strings querycre,queryins,queryup,querydel; querycre = 'Create table XYZ ...'; execute querycre ; queryins = 'Insert into XYZ ...'; execute queryins ; queryup = 'Update XYZ set ...'; execute queryup; querydel = 'Delete from XYZ ...'; execute querydel ; and Strings query; query= 'Create table XYZ ... '; execute query ; query= 'Insert into XYZ ...'; execute query ; query= 'Update XYZ set ...'; execute query ; query= 'Delete from XYZ ...'; execute query ; In first case I use 4 strings each storing data to perform the actions mentioned in their suffixes. In second case just 1 variable to store all kinds the data. Having different variables makes it easier for someone else to read and understand it better. But having too many of them makes it difficult to manage. Also does having too many variables hamper my performance?

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  • undefined control sequence in a NOWEB document

    - by Jean Baldraque
    I'm writing a TeX-noweb document. I compile it with noweave -tex -filter "elide comment:*" texcode.nw > documentation.tex but when I try to compile the resulting file with xetex -halt-on-error documentation.tex I obtain the following error message ! Undefined control sequence. <argument> ...on}\endmoddef \nwstartdeflinemarkup \nwenddeflinemarkup It seems that \nwenddeflinemarkup is not recognized. If i delete from the document all the sequences \nwstartdeflinemarkup\nwenddeflinemarkup the document compile without exceptions. What can be the problem?

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  • How to implement child-parent aggregation link in C++?

    - by Giorgio
    Suppose that I have three classes P, C1, C2, composition (strong aggregation) relations between P <>- C1 and P <>- C2, i.e. every instance of P contains an instance of C1 and an instance of C2, which are destroyed when the parent P instance is destroyed. an association relation between instances of C1 and C2 (not necessarily between children of the same P). To implement this, in C++ I normally define three classes P, C1, C2, define two member variables of P of type boost::shared_ptr<C1>, boost::shared_ptr<C2>, and initialize them with newly created objects in P's constructor, implement the relation between C1 and C2 using a boost::weak_ptr<C2> member variable in C1 and a boost::weak_ptr<C1> member variable in C2 that can be set later via appropriate methods, when the relation is established. Now, I also would like to have a link from each C1 and C2 object to its P parent object. What is a good way to implement this? My current idea is to use a simple constant raw pointer (P * const) that is set from the constructor of P (which, in turn, calls the constructors of C1 and C2), i.e. something like: class C1 { public: C1(P * const p, ...) : paren(p) { ... } private: P * const parent; ... }; class P { public: P(...) : childC1(new C1(this, ...)) ... { ... } private: boost::shared_ptr<C1> childC1; ... }; Honestly I see no risk in using a private constant raw pointer in this way but I know that raw pointers are often frowned upon in C++ so I was wondering if there is an alternative solution.

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  • Why to say, my function is of IFly type rather than saying it's Airplane type

    - by Vishwas Gagrani
    Say, I have two classes: Airplane and Bird, both of them fly. Both implement the interface IFly. IFly declares a function StartFlying(). Thus both Airplane and Bird have to define the function, and use it as per their requirement. Now when I make a manual for class reference, what should I write for the function StartFlying? 1) StartFlying is a function of type IFly . 2) StartFlying is a function of type Airplane 3) StartFlying is a function of type Bird. My opinion is 2 and 3 are more informative. But what i see is that class references use the 1st one. They say what interface the function is declared in. Problem is, I really don't get any usable information from knowing StartFlying is IFly type. However, knowing that StartFlying is a function inside Airplane and Bird, is more informative, as I can decide which instance (Airplane or Bird ) to use. Any lights on this: how saying StartFlying is a function of type IFly, can help a programmer understanding how to use the function?

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  • Is 2 lines of push/pop code for each pre-draw-state too many?

    - by Griffin
    I'm trying to simplify vector graphics management in XNA; currently by incorporating state preservation. 2X lines of push/pop code for X states feels like too many, and it just feels wrong to have 2 lines of code that look identical except for one being push() and the other being pop(). The goal is to eradicate this repetitiveness,and I hoped to do so by creating an interface in which a client can give class/struct refs in which he wants restored after the rendering calls. Also note that many beginner-programmers will be using this, so forcing lambda expressions or other advanced C# features to be used in client code is not a good idea. I attempted to accomplish my goal by using Daniel Earwicker's Ptr class: public class Ptr<T> { Func<T> getter; Action<T> setter; public Ptr(Func<T> g, Action<T> s) { getter = g; setter = s; } public T Deref { get { return getter(); } set { setter(value); } } } an extension method: //doesn't work for structs since this is just syntatic sugar public static Ptr<T> GetPtr <T> (this T obj) { return new Ptr<T>( ()=> obj, v=> obj=v ); } and a Push Function: //returns a Pop Action for later calling public static Action Push <T> (ref T structure) where T: struct { T pushedValue = structure; //copies the struct data Ptr<T> p = structure.GetPtr(); return new Action( ()=> {p.Deref = pushedValue;} ); } However this doesn't work as stated in the code. How might I accomplish my goal? Example of code to be refactored: protected override void RenderLocally (GraphicsDevice device) { if (!(bool)isCompiled) {Compile();} //TODO: make sure state settings don't implicitly delete any buffers/resources RasterizerState oldRasterState = device.RasterizerState; DepthFormat oldFormat = device.PresentationParameters.DepthStencilFormat; DepthStencilState oldBufferState = device.DepthStencilState; { //Rendering code } device.RasterizerState = oldRasterState; device.DepthStencilState = oldBufferState; device.PresentationParameters.DepthStencilFormat = oldFormat; }

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  • "Imprinting" as a language feature?

    - by MKO
    Idea I had this idea for a language feature that I think would be useful, does anyone know of a language that implements something like this? The idea is that besides inheritance a class can also use something called "imprinting" (for lack of better term). A class can imprint one or several (non-abstract) classes. When a class imprints another class it gets all it's properties and all it's methods. It's like the class storing an instance of the imprinted class and redirecting it's methods/properties to it. A class that imprints another class therefore by definition also implements all it's interfaces and it's abstract class. So what's the point? Well, inheritance and polymorphism is hard to get right. Often composition gives far more flexibility. Multiple inheritance offers a slew of different problems without much benefits (IMO). I often write adapter classes (in C#) by implementing some interface and passing along the actual methods/properties to an encapsulated object. The downside to that approach is that if the interface changes the class breaks. You also you have to put in a lot of code that does nothing but pass things along to the encapsulated object. A classic example is that you have some class that implements IEnumerable or IList and contains an internal class it uses. With this technique things would be much easier Example (c#) [imprint List<Person> as peopleList] public class People : PersonBase { public void SomeMethod() { DoSomething(this.Count); //Count is from List } } //Now People can be treated as an List<Person> People people = new People(); foreach(Person person in people) { ... } peopleList is an alias/variablename (of your choice)used internally to alias the instance but can be skipped if not needed. One thing that's useful is to override an imprinted method, that could be achieved with the ordinary override syntax public override void Add(Person person) { DoSomething(); personList.Add(person); } note that the above is functional equivalent (and could be rewritten by the compiler) to: public class People : PersonBase , IList<Person> { private List<Person> personList = new List<Person>(); public override void Add(object obj) { this.personList.Add(obj) } public override int IndexOf(object obj) { return personList.IndexOf(obj) } //etc etc for each signature in the interface } only if IList changes your class will break. IList won't change but an interface that you, someone in your team, or a thirdparty has designed might just change. Also this saves you writing a whole lot of code for some interfaces/abstract classes. Caveats There's a couple of gotchas. First we, syntax must be added to call the imprinted classes's constructors from the imprinting class constructor. Also, what happends if a class imprints two classes which have the same method? In that case the compiler would detect it and force the class to define an override of that method (where you could chose if you wanted to call either imprinted class or both) So what do you think, would it be useful, any caveats? It seems it would be pretty straightforward to implement something like that in the C# language but I might be missing something :) Sidenote - Why is this different from multiple inheritance Ok, so some people have asked about this. Why is this different from multiple inheritance and why not multiple inheritance. In C# methods are either virtual or not. Say that we have ClassB who inherits from ClassA. ClassA has the methods MethodA and MethodB. ClassB overrides MethodA but not MethodB. Now say that MethodB has a call to MethodA. if MethodA is virtual it will call the implementation that ClassB has, if not it will use the base class, ClassA's MethodA and you'll end up wondering why your class doesn't work as it should. By the terminology sofar you might already confused. So what happens if ClassB inherits both from ClassA and another ClassC. I bet both programmers and compilers will be scratching their heads. The benefit of this approach IMO is that the imprinting classes are totally encapsulated and need not be designed with multiple inheritance in mind. You can basically imprint anything.

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  • Everything has an Interface [closed]

    - by Shane
    Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast majority of these interfaces are implemented by a single class that share a similar name and the exact same methods (ex: MyCar and MyCarImpl). Almost no 2 classes in the project implement more than the interface that shares its name. I know the general recommendation is to code to an interface rather than an implementation, but isn't this taking it a bit too far? The system might be more flexible in that it is easier to add a new class that behaves very much like an existing class. However, it is significantly harder to parse through the code and method changes now require 2 edits instead of 1. Personally, I normally only create interfaces when there is a need for multiple classes to have the same behavior. I subscribe to YAGNI, so I don't create something unless I see a real need for it. Am I doing it all wrong or is this project going way overboard?

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  • graphical interface when using assembly language

    - by Hellbent
    Im looking to use assembly language to make a great game, not just an average game but a really great game. I want to learn a framework to use in assembly. I know thats not possible without learning the framework in c first. So im thinking of learning sdl in c and then learn, teach myself, how to interpret the program and run it as assembly language code which shouldnt be that hard. Then i will have a window and some graphics routines to display the game while using assembly to code everything in. I need to spend some time learning sdl and then some more time learning how to code all those statements using assembly while calling c functions and knowing what registers returned calls use and what they leave etc. My question is , Is this a good way to go or is there something better to get a graphical window display using assembly language? Regards HellBent

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  • Defining formula through user interface in user form

    - by BriskLabs Pakistan
    I am a student and developing a simple assignment - windows form application in visual studio 2010. The application is suppose to construct formulas as per user requirement. The process: It has to pick data from columns of Microsoft Access database and the user should be able to pick the data by column name like we do in a drop down menu. and create reusable formulas in it ( configure it once and can change it again). followings are column titles from database that can be picked for example. e.g Col -1 : Marks in Maths Col -2 : Total Marks in Maths Col -3 : Marks in science Col -4 : Total marks in science Finally we should be able to construct any formula in the UI like (Col 1 + Col 3 ) / ( col 2 + col 4) = Formula 1 once this is formula is set saved and a name is assigned to it by user. he/she can use the formula and results shall appear in a window below. i.e He would be able to calculate his desired figures (formula) by only manipulating underlying data on the UI layer....choose the data for a period and apply the formula and get the answer Problem: It looks like I have to create an app where rules are set through UI....... this means no stored procedures are required in SQL.... please suggest the right approach.

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  • Should we consider code language upon design?

    - by Codex73
    Summary This question aims to conclude if an applications usage will be a consideration when deciding upon development language. What factors if any could be considered upon language writing could be taken into context. Application Type: Web Question Of the following popular languages, when should we use one or the other? What factors if any could be considered upon language writing could be taken into context. Languages PHP Ruby Python My initial thought is that language shouldn't be considered as much as framework. Things to consider on framework are scalability, usage, load, portability, modularity and many more. Things to consider on Code Writing maybe cost, framework stability, community, etc.

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  • Where can I find game postmortems with a programmer perspective [on hold]

    - by Ken
    There are a number of interesting game post-mortems in places like GDC vault or gamastura.com. The post-mortems are generally give with a CEO/manager perspective or a designer perspective, or, more often a combination of both e.g DOOM postmortem But I have not been able to find many post-mortems which are primarily from the programmers perspective. I'm looking for discussions and rational for technical choices and tradeoffs and how technical problems were overcome. The motivation here is to learn what kind of problems real game programmers encounter and how they go about solving them. A perfect example of what I'm looking for is Renaud Bédard's excellent GDC talk on the development of Fez, "Cubes all the way down". Where can I find more like that?

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  • Refactoring and Open / Closed principle

    - by Giorgio
    I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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  • Good book for improving c# skills?

    - by JMarsch
    Hello: I was asked to recommend a good book for a mid-level experienced developer who wants to improve their coding skills (c# developer). I was thinking about: Code Complete: http://www.amazon.com/Code-Complete-Practical-Handbook-Construction/dp/0735619670/ref=sr_1_1?ie=UTF8&qid=1291221928&sr=8-1 The Pragmatic Programmer: http://www.amazon.com/Pragmatic-Programmer-Journeyman-Master/dp/020161622X/ref=sr_1_3?ie=UTF8&qid=1291221928&sr=8-3 or Effective C#: http://www.amazon.com/Effective-Covers-4-0-Specific-Development/dp/0321658701/ref=sr_1_1?s=books&ie=UTF8&qid=1291222038&sr=1-1 What do you think about those? Any other suggestions?

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  • How can i manage my personal notes , code snippets files in one place online [closed]

    - by user1758043
    Whenever i work on any project , then i have so much notes , diagrams files , image s, brainstorming ideas which i want to keep. i want to put them in one place so that i can see the history of my work. Is there any toll whichere i can store this online. my company is using confluence but thats costly for me. I want something for single user but online in clou where i can store Notes Code snippets Diagrams , flowchart Attah files , images Books marks , sites

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  • What is the difference between industrial development and open source development?

    - by Ida
    Intuitively, I think open source development should be much more "casual" than industrial development process (like in Microsoft). Because for OSS development: Duty separation is not that strict than in big companies (maybe developers == testers in open source development?) People come in and out of the open source community, much more frequently than in big companies However, above are just my guesses. I really want to know more about the major difference between the open source and industrial development. Is their division of duty totally different (e.g., is there a leader/manager-like role in open source development?)? Maybe it is their communication style that differs a lot? Or their workflow? Please share your opinions. Thanks a lot!

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  • Is there a point to writing in C or C++ instead of C# without knowing specifically what would make a program faster?

    - by user828584
    I wrote a small library in Python for handling the xbox 360's STFS files to be used on my web applications. I would like to rewrite it for use in the many desktop programs people are writing for 360 game modding, but I'm not quite if I should continue using C# or delve into C++ or even C. STFS is an in-file file system used by the xbox 360 and the job of the library would be extracting/injecting files, which could take noticeable amounts of time to do. What I know in C# comes from internet tutorials and resources, as would anything I learn about C++, so what I'm asking is if it's better to bring myself to a slightly lower-level language without knowing beforehand the features of the language that increase performance, or continue assuming that compiler optimizations and that my lack of experience will mean that the language I choose won't matter.

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  • How does Python compile some its code in C?

    - by Howcan
    I read that some constructs of Python are more efficient because they are compiled in C. https://wiki.python.org/moin/PythonSpeed/PerformanceTips Some of the examples used were map() and filter(). I was wondering how Python is able to do this? It's generally interpreted, so how does some of the code get compiled while another is interpreted - and in a different language? Why not just compile the whole thing?

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  • How to process large files in NetLogo? [closed]

    - by user65597
    I am running into problems in NetLogo with large *.csv / *.txt files. The documents can consist of about 1 million data sets and I need to read them (to eventually create a diagram based on the data). With the most straightforward source code, my program needs about 2 minutes to process these files. How should I approach reading such large data files faster in NetLogo? Is NetLogo even suitable for such tasks (as it seems to be designed more for teaching and learning)?

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  • Techniques for separating game model from presentation

    - by liortal
    I am creating a simple 2D game using XNA. The elements that make up the game world are what i refer to as the "model". For instance, in a board game, i would have a GameBoard class that stores information about the board. This information could be things such as: Location Size Details about cells on the board (occupied/not occupied) etc This object should either know how to draw itself, or describe how to draw itself to some other entity (renderer) in order to be displayed. I believe that since the board only contains the data+logic for things regarding it or cells on it, it should not provide the logic of how to draw things (separation of concerns). How can i achieve a good partitioning and easily allow some other entity to draw it properly? My motivations for doing so are: Allow multiple "implementations" of presentation for a single game entity Easier porting to other environments where the presentation code is not available (for example - porting my code to Unity or other game technology that does not rely on XNA).

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  • Single or multiple return statements in a function [on hold]

    - by Juan Carlos Coto
    When writing a function that can have several different return values, particularly when different branches of code return different values, what is the cleanest or sanest way of returning? Please note the following are really contrived examples meant only to illustrate different styles. Example 1: Single return def my_function(): if some_condition: return_value = 1 elif another_condition: return_value = 2 else: return_value = 3 return return_value Example 2: Multiple returns def my_function(): if some_condition: return 1 elif another_condition: return 2 else: return 3 The second example seems simpler and is perhaps more readable. The first one, however, might describe the overall logic a bit better (the conditions affect the assignment of the value, not whether it's returned or not). Is the second way preferable to the first? Why?

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  • How do I parse a header with two different version [ID3] avoiding code duplication?

    - by user66141
    I really hope you can give me some interesting viewpoints for my situation, because I am not satisfied with my current approach. I am writing an MP3 parser, starting with an ID3v2 parser. Right now I`m working on the extended header parsing, my issue is that the optional header is defined differently in version 2.3 and 2.4 of the tag. The 2.3 version optional header is defined as follows: struct ID3_3_EXTENDED_HEADER{ DWORD dwExtHeaderSize; //Extended header size (either 6 or 8 bytes , excluded) WORD wExtFlags; //Extended header flags DWORD dwSizeOfPadding; //Size of padding (size of the tag excluding the frames and headers) }; While the 2.4 version is defined : struct ID3_4_EXTENDED_HEADER{ DWORD dwExtHeaderSize; //Extended header size (synchsafe int) BYTE bNumberOfFlagBytes; //Number of flag bytes BYTE bFlags; //Flags }; How could I parse the header while minimizing code duplication? Using two different functions to parse each version sounds less great, using a single function with a different flow for each occasion is similar, any good practices for this kind of issues ? Any tips for avoiding code duplication? Any help would be appreciated.

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  • Should I modify an entity with many parameters or with the entity itself?

    - by Saeed Neamati
    We have a SOA-based system. The service methods are like: UpdateEntity(Entity entity) For small entities, it's all fine. However, when entities get bigger and bigger, to update one property we should follow this pattern in UI: Get parameters from UI (user) Create an instance of the Entity, using those parameters Get the entity from service Write code to fill the unchanged properties Give the result entity to the service Another option that I've experienced in previous experiences is to create semantic update methods for each update scenario. In other words instead of having one global all-encompasing update method, we had many ad-hoc parametric methods. For example, for the User entity, instead of having UpdateUser (User user) method, we had these methods: ChangeUserPassword(int userId, string newPassword) AddEmailToUserAccount(int userId, string email) ChangeProfilePicture(int userId, Image image) ... Now, I don't know which method is truly better, and for each approach, we encounter problems. I mean, I'm going to design the infrastructure for a new system, and I don't have enough reasons to pick any of these approaches. I couldn't find good resources on the Internet, because of the lack of keywords I could provide. What approach is better? What pitfalls each has? What benefits can we get from each one?

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  • Why Nodes.js being that "unique"?

    - by Adrian Shum
    Recently years there are lots of praise to Nodes.js. I am not a developer that have much exposure on network application. From my bare understanding of Nodes.js, its strength is: We are having only on thread handling multiple connections, providing a event-based architecture. However, for example in Java, what if I am having only one thread, using NIO/AIO (which is non-blocking APIs from my bare understanding), and handle multiple connections using that thread, and I provide an event-based architecture to implement the data handling logic (shouldn't be that difficult by providing some callback etc) ? Given JVM being a even more mature VM than V8 (I expect it run faster too), and event-based handling architecture seems not something difficult to create. I am not sure why Nodes.js is attracting so much attention. Did I miss some important points?

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  • Should I forward the a call to .Equals onto .Equals<T>?

    - by Jaimal Chohan
    So, I've got you bog standard c# object, overriding Equalsand implementing IEquatable public override int GetHashCode() { return _name.GetHashCode(); } public override bool Equals(object obj) { return Equals(obj as Tag) } #region IEquatable<Tag> Members public bool Equals(Tag other) { if (other == null) return false; else return _name == other._name; } #endregion Now, for some reason, I used to think that forwarding the calls from Equals into Equals was bad, no idea why, perhaps I read it a long time ago, anyway I'd write separate (but logically same) code for each method. Now I think forwarding Equals to Equals is okay, for obvious reasons, but for the life me I can't remember why I thought it wasn't before. Any thoughts?

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  • How do references work in R?

    - by djechlin
    I'm finding R confusing because it has such a different notion of reference than I am used to in languages like C, Java, Javascript... Ruby, Python, C++, well, pretty much any language I have ever programmed in ever. So one thing I've noticed is variable names are not irrelevant when passing them to something else. The reference can be part of the data. e.g. per this tutorial a <- factor(c("A","A","B","A","B","B","C","A","C")) results <- table(a) Leads to $a showing up as an attribute as $dimnames$a. We've also witnessed that calling a function like a <- foo(alpha=1, beta=2) can create attributes in a of names alpha and beta, or it can assign or otherwise compute on 1 and 2 to properties already existing. (Not that there's a computer science distinction here - it just doesn't really happen in something like Javascript, unless you want to emulate it by passing in the object and use key=value there.) Functions like names(...) return lvalues that will affect the input of them. And the one that most got me is this. x <- c(3, 5, 1, 10, 12, 6) y = x[x <= 5] x[y] <- 0 is different from x <- c(3, 5, 1, 10, 12, 6) x[x <= 5] <- 0 Color me confused. Is there a consistent theory for what's going on here?

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