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  • Strategies for serializing an object for auditing/logging purpose in .NET?

    - by Jiho Han
    Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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  • Is there an equivalent in Scala to Python's more general map function?

    - by wheaties
    I know that Scala's Lists have a map implementation with signature (f: (A) => B):List[B] and a foreach implementation with signature (f: (A) => Unit):Unit but I'm looking for something that accepts multiple iterables the same way that the Python map accepts multiple iterables. I'm looking for something with a signature of (f: (A,B) => C, Iterable[A], Iterable[B] ):Iterable[C] or equivalent. Is there a library where this exists or a comparable way of doing similar?

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  • Which Cortex-M3 interrupts can I use for general purpose work?

    - by Captain NedD
    I'd have some code that needs to be run as the result of a particular interrupt going off. I don't want to execute it in the context of the interrupt itself but I also don't want it to execute in thread mode. I would like to run it at a priority that's lower than the high level interrupt that precipitated its running but also a priority that higher than thread level (and some other interrupts as well). I think I need to use one of the other interrupt handlers. Which ones are the best to use and what the best way to invoke them? At the moment I'm planning on just using the interrupt handlers for some peripherals that I'm not using and invoking them by setting bits directly through the NVIC but I was hoping there's a better, more official way. Thanks,

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  • What is the general feeling about reflection extensions in std::type_info?

    - by Evan Teran
    I've noticed that reflection is one feature that developers from other languages find very lacking in c++. For certain applications I can really see why! It is so much easier to write things like an IDE's auto-complete if you had reflection. And certainly serialization APIs would be a world easier if we had it. On the other side, one of the main tenets of c++ is don't pay for what you don't use. Which makes complete sense. That's something I love about c++. But it occurred to me there could be a compromise. Why don't compilers add extensions to the std::type_info structure? There would be no runtime overhead. The binary could end up being larger, but this could be a simple compiler switch to enable/disable and to be honest, if you are really concerned about the space savings, you'll likely disable exceptions and RTTI anyway. Some people cite issues with templates, but the compiler happily generates std::type_info structures for template types already. I can imagine a g++ switch like -fenable-typeinfo-reflection which could become very popular (and mainstream libs like boost/Qt/etc could easily have a check to generate code which uses it if there, in which case the end user would benefit with no more cost than flipping a switch). I don't find this unreasonable since large portable libraries like this already depend on compiler extensions. So why isn't this more common? I imagine that I'm missing something, what are the technical issues with this?

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  • Searches (and general querying) with HBase and/or Cassandra (best practices?)

    - by alexeypro
    I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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  • Silverlight Vs. WPF Vs. Winforms What is good for specifically my purpose?

    - by Cyril Gupta
    I am about to start a new Windows applications and the contenders for the platform are: Windows Forms WPF Silverlight Now my experience with WPF at least in my last application was not very encouraging (the app failed to run on the deployment machines and I had to re-do it in Winforms). So my confidence is shaken here. My app is for mass-distribution (the last version had some 100,000+ installations). So I want to make absolutely sure that my users will be able to use it and enjoy it without any problems. I would love to create a nice interface, going the next step like a Flex or Silverlight, iPhone app, with animations and effects. So I would really like to go with WPF or Silverlight if I can. My needs are Good support for visuals and animation effects. Support for database connectivity. Support for printing (Is there an equivalent of PrintDocument in Silverlight) Must not suffer from deployment troubles. Silverlight is universal, but does it have printing support and good controls toolset? WPF has printing support and a nice toolset, but can I depend on it? Winforms is dated already and is not so impressive, but should I go with it anyway? Your advice would be appreciated

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  • What's the best general programming book to review basic development concepts?

    - by Charles S.
    I'm looking for for a programming book that reviews basic concepts like implementing linked lists, stacks, queues, hash tables, tree traversals, search algorithms, etc. etc. Basically, I'm looking for a review of everything I learned in college but have forgotten. I prefer something written in the last few years that includes at least a decent amount of code in object-oriented languages. This is to study for job interview questions but I already have the "solving interview questions" books. I'm looking for something with a little more depth and explanation. Any good recommendations?

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  • .NET: What is the purpose of the ProhibitDtd property in XmlReaderSettings? Why is DTD a security i

    - by Cheeso
    The documentation says: When set to true, the XmlReader throws an XmlException when any DTD content is encountered. Do not enable DTD processing if you are concerned about Denial of Service issues or if you are dealing with untrusted sources. If you have DTD processing enabled, you can use the XmlSecureResolver to restrict the resources that the XmlReader can access. You can also design your application so that the XML processing is memory and time constrained. For example, configure time-out limits in your ASP.NET application. Can someone please explain the issue? Why would a reader application want to prohibit the retrieval of a DTD? Where is the denial-of-service issue, if it is a reading application? What is the "trust" issue that is mentioned? Thanks

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  • How do I specify a keys password with MSBuild for the purpose of using Hudson?

    - by Brett Ryan
    We have just setup our hudson server to build .NET projects which seems to be working fine, however for projects that require a password when signing the assemblies I can not figure out how to tell hudson what the password is? For us the password is asked the first time a developer checks out the source code and they open with visual studio, how is this stored? Can we just place a secret file somewhere on the server?

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  • How can I determine if there is an open source software for a specific purpose?

    - by afsharm
    Hi, We are going to write an entire new application for a reservation system. In this system experts specify their free time in elaborated calendar and users seek them through searched and finally reserve the expert and his time. We prefer to find an open source program like this and try to evolve it instead of creating it from scratch. In this manner our time is saved and that open source program will be completer too. We are a entire .NET (ASP.NET, C#, NHibernate) company. We have same problem to find open source applications for our new projects. Any help is highly appreciated.

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  • c#: what is the purpose of wpf vs. winforms [closed]

    - by every_answer_gets_a_point
    i know wpf can be richer-looking, but what is the point of using them if they complicate things so much? for example if i want to do something on form load in wpf i have to through the trouble of writing this: public MyWindow() { Loaded += MyWindow_Loaded; } private void MyWindow_Loaded(object sender, RoutedEventArgs e) { // do work here } whereas in winforms all i do is double click on the form the question is what are the benefits of using wpf over winforms?

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  • What is the main purpose and sense to have staging server the same as production?

    - by truthseeker
    Hi, In our company we have staging and production servers. I'm trying to have them in state 1:1 after latest release. We've got web application running on several host and many instances of it. The issue is that I am an advocate of having the same architecture (structure) of web applications on staging and production servers to easily test new features and avoid creating of new bugs with new releases. But not everyone agree with me, and for them is not a such big deal to have different connection between staging application instances. Even maybe to have more application and connections between application on staging than on production server. I would like to ask about pros and cons of such an approach? I mean some good points to agree with me, or some bad why maybe i don't have right. Some examples of consequences and so forth.

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  • What do I name this class whose sole purpose is to report failure?

    - by Blair Holloway
    In our system, we have a number of classes whose construction must happen asynchronously. We wrap the construction process in another class that derives from an IConstructor class: class IConstructor { public: virtual void Update() = 0; virtual Status GetStatus() = 0; virtual int GetLastError() = 0; }; There's an issue with the design of the current system - the functions that create the IConstructor-derived classes are often doing additional work which can also fail. At that point, instead of getting a constructor which can be queried for an error, a NULL pointer is returned. Restructuring the code to avoid this is possible, but time-consuming. In the meantime, I decided to create a constructor class which we create and return in case of error, instead of a NULL pointer: class FailedConstructor : public IConstructor public: virtual void Update() {} virtual Status GetStatus() { return STATUS_ERROR; } virtual int GetLastError() { return m_errorCode; } private: int m_errorCode; }; All of the above this the setup for a mundane question: what do I name the FailedConstructor class? In our current system, FailedConstructor would indicate "a class which constructs an instance of Failed", not "a class which represents a failed attempt to construct another class". I feel like it should be named for one of the design patterns, like Proxy or Adapter, but I'm not sure which.

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  • How Can I Create Reports in a Custom C#.NET Windows Application? - General Question

    - by user311509
    Assume i have a custom Windows application written in C#. This application has only the following functionalists, add, edit, delete and view. For example, a user can add a sale, change sales record, delete a sale record or view the whole sales record. I need to add some reporting functionalists e.g. i want a user to print the sales of a certain customer from 2008 to 2009 into pdf, what all products a certain customer has purchased from us and so on. I will only include the basic common report requests that are usually needed in the office. Any other kind of reports that are requested inconsistently, i would do it manually from my side at the back end and send the results manually to the requester. What i would do is: If a user wants more info of a certain customer, a special window box appears for that customer. This window box will have different controls that allows user to request more info such as, print customer purchases from ..... to ..... (user chooses the dates) and user will view results in pdf or so. Of course, at the back scene i will write an appropriate SQL Query with parameters that meets a certain function. Is this how it should be done? I have heard about SQL Reporting, i don't know anything about it yet. I will check it out. Anyhow, your suggestions won't harm. I'm still a student, so i don't have practical experience yet. I hope my question is clear enough. Thank you.

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  • Is using a FSM a good design for general text parsing?

    - by eSKay
    I am reading a file that is filled with hex numbers. I have to identify a particular pattern, say "aaad" (without quotes) from it. Every time I see the pattern, I generate some data to some other file. This would be a very common case in designing programs - parsing and looking for a particular pattern. I have designed it as a Finite State Machine and structured structured it in C using switch-case to change states. This was the first implementation that occured to me. DESIGN: Are there some better designs possible? IMPLEMENTATION: Do you see some problems with using a switch case as I mentioned?

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  • Is the Keychain suitable for storing general data, such as strings?

    - by cannyboy
    The Keychain seems to be used a lot for usernames and passwords, but is it a good idea to use it for other sensitive stuff (bank details, ID numbers etc), but with no password? What kind of encryption does the keychain use? The scenario I'm concerned about is a thief acquiring an iPhone (which is screen-locked) and being able to access the file system to get this info. Also, would using the Keychain involve export restrictions due to the use of encryption?

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  • What's the purpose of the lua "stub" dll for windows.

    - by Roddy
    I'm looking at incorporating Lua into a C++ project, and am a bit confused by the presence of the two binaries (lua51.dll and lua5.1.dll) in the distribution from Luabinaries. According to the docs... In Windows your library or application must be linked with a stub library. A stub library is a library with only the function declarations that will bind your DLL with the Lua DLL. Why? I've never needed stub DLLs before when linking with third-party DLLs?

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  • What is the purpose of Java's unary plus operator?

    - by Syntactic
    Java's unary plus operator appears to have come over from C, via C++. As near as I can tell, it has the following effects: promotes its operand to int, if it's not already an int or wider unboxes its operand, if it's a wrapper object complicates slightly the parsing of evil expressions containing large numbers of consecutive plus signs It seems to me that there are better (or, at least, clearer) ways to do all of these things. In this SO question, concerning the counterpart operator in C#, someone said that "It's there to be overloaded if you feel the need." But in Java, one cannot overload any operator. So does this operator exist in Java just because it existed in C++?

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  • What is the proper way to assign a general udf to application.cfc?

    - by Tom Hubbard
    I simply want to define a function in application.cfc and expose it application wide to all requests. Preferably the "assignment" would only happen on application startup. Is the preferred method to do something along the lines of this: <CFCOMPONENT OUTPUT="FALSE"> <CFSET this.name = "Website"> <CFSET this.clientManagement = true> <CFSET this.SessionManagement = true> <CFFUNCTION NAME="GetProperty" OUTPUT="False"> <CFARGUMENT NAME="Property"> <CFRETURN this.Props[Property]> </CFFUNCTION> <CFFUNCTION NAME="OnApplicationStart" OUTPUT="FALSE"> <CFSET Application.GetProperty = GetProperty> . . . or is there something better?

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  • What is the purpose of the s==NULL case for mbrtowc?

    - by R..
    mbrtowc is specified to handle a NULL pointer for the s (multibyte character pointer) argument as follows: If s is a null pointer, the mbrtowc() function shall be equivalent to the call: mbrtowc(NULL, "", 1, ps) In this case, the values of the arguments pwc and n are ignored. As far as I can tell, this usage is largely useless. If ps is not storing any partially-converted character, the call will simply return 0 with no side effects. If ps is storing a partially-converted character, then since '\0' is not valid as the next byte in a multibyte sequence ('\0' can only be a string terminator), the call will return (size_t)-1 with errno==EILSEQ. and leave ps in an undefined state. The intended usage seems to have been to reset the state variable, particularly when NULL is passed for ps and the internal state has been used, analogous to mbtowc's behavior with stateful encodings, but this is not specified anywhere as far as I can tell, and it conflicts with the semantics for mbrtowc's storage of partially-converted characters (if mbrtowc were to reset state when encountering a 0 byte after a potentially-valid initial subsequence, it would be unable to detect this dangerous invalid sequence). If mbrtowc were specified to reset the state variable only when s is NULL, but not when it points to a 0 byte, a desirable state-reset behavior would be possible, but such behavior would violate the standard as written. Is this a defect in the standard? As far as I can tell, there is absolutely no way to reset the internal state (used when ps is NULL) once an illegal sequence has been encountered, and thus no correct program can use mbrtowc with ps==NULL.

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  • What is the purpose of "do!" notation in F#?

    - by Yacoder
    I'm a beginner in F#, so it's a simple question and maybe a duplicate, but I couldn't find the answer anywhere... I'm reading this LOGO DSL implementation and I don't understand, what is the meaning of the "do!" notation in here: this.Loaded.Add (fun _ -> async { do! Async.Sleep 200 for cmd in theDrawing do do! this.Execute(cmd) } |> Async.StartImmediate ) Can you help?

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  • What is the point/purpose of Ruby EventMachine, Python Twisted, or JavaScript Node.js?

    - by CCw
    I don't understand what problem these frameworks solve. Are they replacements for a HTTP server like Apache HTTPD, Tomcat, Mongrel, etc? Or are they more? Why might I use them... some real world examples? I've seen endless examples of chat rooms and broadcast services, but don't see how this is any different than, for instance, setting up a Java program to open sockets and dispatch a thread for each request. I think I understand the non-blocking I/O, but I don't understand how that is any different than a multi-threaded web server.

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