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  • How to convert an existing callback interface to use boost signals & slots

    - by the_mandrill
    I've currently got a class that can notify a number of other objects via callbacks: class Callback { virtual NodulesChanged() =0; virtual TurkiesTwisted() =0; }; class Notifier { std::vector<Callback*> m_Callbacks; void AddCallback(Callback* cb) {m_Callbacks.push(cb); } ... void ChangeNodules() { for (iterator it=m_Callbacks.begin(); it!=m_Callbacks.end(); it++) { (*it)->NodulesChanged(); } } }; I'm considering changing this to use boost's signals and slots as it would be beneficial to reduce the likelihood of dangling pointers when the callee gets deleted, among other things. However, as it stands boost's signals seems more oriented towards dealing with function objects. What would be the best way of adapting my code to still use the callback interface but use signals and slots to deal with the connection and notification aspects?

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  • Using ManagementObject to retrieve a single WMI property

    - by Jesse
    This probably isn't the best way, but I am currently retrieving the amount of RAM on a machine using: manageObjSearch.Query = new ObjectQuery("SELECT TotalVisibleMemorySize FROM Win32_OperatingSystem"); manageObjCol = manageObjSearch.Get(); foreach (ManagementObject mo in manageObjCol) sizeInKilobytes = Convert.ToInt64(mo["TotalVisibleMemorySize"]); It works well and good, but I feel I could be doing this more directly and without a foreach over a single element, but I can't figure out how to index a ManagementObjectCollection I want to do something like this: ManagementObject mo = new ManagementObject("Win32_OperatingSystem.TotalVisibleMemorySize") mo.Get(); Console.WriteLine(mo["TotalVisibleMemorySize"].ToString()) or maybe even something like ManagementClass mc = new ManagementClass("Win32_OperatingSystem"); Console.WriteLine(mc.GetPropertyValue("TotalVisibleMemorySize").ToString()); I just can't seem to figure it out. Any ideas?

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  • How can I easily get a TextReader from an XDocument?

    - by Mark Seemann
    Given an XDocument instance, how can I easily get a TextReader that represents that instance? The best I've been able to come up with is something like this (where xml is an XDocument instance): var s = new MemoryStream(); var sw = new StreamWriter(s); xml.Save(sw); sw.Flush(); s.Position = 0; TextReader tr = new StreamReader(s); However, this seems a little clunky, so I was wondering if there's an easier way?

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  • How to write async background workers that work on WPF flowdocument

    - by iBe
    I'm trying to write a background worker that processes a flowdocument. I can't access the properties of flowdocument objects because of the thread verification. I tried to serialize the document and loaded it on the worker thread which actually solved the thread verfication issue. However, once the processing is complete I also need to use things like TextPointer objects. Those objects now point to a objects in the copy not the original. Can anyone suggest the best way to approach such background processing in WPF?

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  • javascript filter array of objects

    - by user441521
    I have an array of objects and I'm wondering the best way to search it. Given the below example how can I search for name = "Joe" and age < 30? Is there anything jQuery can help with or do I have to brute force this search myself? var names = new Array(); var object = { name : "Joe", age:20, email: "[email protected]"}; names.push(object); object = { name : "Mike", age:50, email: "[email protected]"}; names.push(object); object = { name : "Joe", age:45, email: "[email protected]"}; names.push(object);

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  • Using the Module Pattern for larger projects

    - by Rob
    I'm interested in using the Module Pattern to better organize my future projects. Unfortunately, there are only a few brief tutorials and proof-of-concept examples of the Module Pattern. Using the module pattern, I would like to organize projects into this sort of structure: project.arm.object.method(); Where "project" is my global project name, "arm" is a sub-section or branch of the project, "object" is an individual object, and so on to the methods and properties. However, I'm not sure how I should be declaring and organizing multiple "arms" and "objects" under "project". var project = window.project || {}; project.arm = project.arm || {}; project.arm.object = (function() { var privateVar = "Private contents."; function privateMethod() { alert(privateVar); } return { method: privateMethod }; }()); Are there any best practices or conventions when defining a complex module structure? Should I just declare a new arm/object underneath the last?

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  • Define variable in variable/parameter and use in javascript?

    - by Ross
    I want to defined a variable/parameter in CSS and access it by javascript. What is the best way of doing this? One option I thought of would be to place a cutsom attribute on the body element, then access that attribute via jQuery. A little more info: I'm defining colour sets in CSS. I've created a function with RaphaelJS to draw a gradient background on the page. I want this function to use a highlight colour (which is not used elsewhere on the DOM) which will be defined in the CSS along with the other colour elements. Thanks

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  • PHP / MySQL - How to retrieve 2 separate sets of objects?

    - by Dan
    Hi, I have a set of models which correspond to tables in my database. I have been retrieving them easily enough, for example. $result = $mysqli->query('SOME SQL'); $post = $result->fetch_object; What would be the best approach for performing a join and also returning the related objects? For example, each post is created by a user, so for each row returned in the joined statement, both a page and user object should be returned. Any advice appreciated. Thanks.

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  • Understanding OpenGL Matrices

    - by Omega
    I'm starting to learn about 3D rendering and I've been making good progress. I've picked up a lot regarding matrices and the general operations that can be performed on them. One thing I'm still not quite following is OpenGL's use of matrices. I see this (and things like it) quite a lot: x y z n ------- 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 So my best understanding, is that it is a normalized (no magnitude) 4 dimensional, column-major matrix. Also that this matrix in particular is called the "identity matrix". Some questions: What is the "nth" dimension? How and when are these applied? My biggest confusion arises from how OpenGL makes use of this kind of data.

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  • What should every programmer know?

    - by Matt Lacey
    Regardless of programming language(s) or operating system(s) used or the environment they develop for, what should every programmer know? Some background: I'm interested in becoming the best programmer I can. As part of this process I'm trying to understand what I don't know and would benefit me a lot if I did. While there are loads of lists around along the lines of "n things every [insert programming language] developer should know", I have yet to find anything similar which isn't limited to a specific language. I also expect this information to be of interest and benefit to others.

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  • Convert a sequence of sequences to a dictionary and vice-versa

    - by louis
    One way to manually persist a dictionary to a database is to flatten it into a sequence of sequences and pass the sequence as an argument to cursor.executemany(). The opposite is also useful, i.e. reading rows from a database and turning them into dictionaries for later use. What's the best way to go from myseq to mydict and from mydict to myseq? >>> myseq = ((0,1,2,3), (4,5,6,7), (8,9,10,11)) >>> mydict = {0: (1, 2, 3), 8: (9, 10, 11), 4: (5, 6, 7)}

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  • explicit copy constructor or implicit parameter by value

    - by R Samuel Klatchko
    I recently read (and unfortunately forgot where), that the best way to write operator= is like this: foo &operator=(foo other) { swap(*this, other); return *this; } instead of this: foo &operator=(const foo &other) { foo copy(other); swap(*this, copy); return *this; } The idea is that if operator= is called with an rvalue, the first version can optimize away construction of a copy. So when called with a rvalue, the first version is faster and when called with an lvalue the two are equivalent. I'm curious as to what other people think about this? Would people avoid the first version because of lack of explicitness? Am I correct that the first version can be better and can never be worse?

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  • Designing a state machine in C++

    - by skyeagle
    I have a little problem that involves modelling a state machine. I have managed to do a little bit of knowledge engineering and 'reverse engineer' a set of primitive deterministic rules that determine state as well as state transitions. I would like to know what the best practises are regarding: How to rigorously test my states and state transitions to make sure that the system cannot end up in an undeetermined state. How to enforce state transition requirements (for example, it should be impossible to go directly from stateFoo to StateFooBar, i.e. to embue each state with 'knowlege' about the states it can transition to. Ideally, I would like to use clean, pattern based design, with templates wherever possible. I do need somewhere to start though and I would be grateful for any pointers (no pun intended), that are sent my way.

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  • Most efficient way to solve system of equations involving the digamma function?

    - by Neil G
    What is the most efficient way to solve system of equations involving the digamma function? I have a vector v and I want to solve for a vector w such that for all i: digamma(sum(w)) - digamma(w_i) = v_i and w_i 0 I found the gsl function gsl_sf_psi, which is the digamma function. Is there an identity I can use to reduce the equations? Is my best bet to use a solver? I am using C++0x; which solver is easiest to use and fast?

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  • Zend + Pop Up's balloons on Server Problem

    - by LookUp Webmaster
    Dear Friends from Stackoverflow, Please help me with a problem that i'm having when uploading my project to the server. I'm using pop up's balloons (http://mckay.cshl.edu/balloons.html) for a project using Zend FW and it works fine on my localhost. (I'm using MAMP on MacOSX) but when I upload the webpage to the server, the text inside the balloons is displayed but the images that form the balloon are not, so somehow the js does not recognize the url to the images (the path it's correct, i've checked several times). The server is an Ubuntu 9.04 virtual machine from rackspace.com, running a LAMP server. I'm using the REWRITE function in Apache, so i guess maybe that's the problem. The rewrite configuration is set up using a .htaccess file with the following content: SetEnv APPLICATION_ENV development Options +FollowSymlinks RewriteEngine ON RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule !.(js|ico|txt|gif|jpg|png|css|html)$ index.php Does anyone knows what the problem might be? Best Regards,

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  • Saving data so it can be loaded locally

    - by Thomas Joos
    hi guys, i'm working on iphone application which needs to run offline at an exhibition. It should present data, stored local because there is no internet at the booth. Still, to easily have content updates it should be able to update it's content once connected to internet. It's quite some data ( around 300 full lines of text ) and I want it to be loaded, stored and visualized as optimized as possible. What's the best way to load in content once connected and how should I store it on the device?

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  • In C#, can I hide/modify accessors in subclasses?

    - by Diego
    I'm not even sure what this principle is called or how to search for it, so I sincerely apologize if it has been brought up before, but the best way to do it is with an example. class Properties { public string Name { get; set; } } class MyClass { class SubProperties: Properties { public override Name { get { return GetActualName(); } set { _value = SetActualName(value); } } } public SubProperties ClassProperties; private GetActualName() { ClassProperties.Name = "name"; } private SetActualName(string s) { ClassProperties.Name = SomeOtherFunction(s); } } The idea is to have any object that instantiates MyClass have a fully accessible property ClassProperties. To that object, it would look exactly like a Properties object, but behind the scenes, MyClass is actually computing and modifying the results of the fields. This method of declaration is obviously wrong since I can't access GetActualName() and SetActualName() from within the SubProperties definition. How would I achieve something like this?

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  • If you're not supposed to use Regular Expressions to parse HTML, then how are HTML parsers written?

    - by Andy E
    I see questions every day asking how to parse or extract something from some HTML string and the first answer/comment is always "Don't use RegEx to parse HTML, lest you feel the wrath!" (that last part is sometimes omitted). This is rather confusing for me, I always thought that in general, the best way to parse any complicated string is to use a regular expression. So how does a HTML parser work? Doesn't it use regular expressions to parse. One particular argument for using a regular expression is that there's not always a parsing alternative (such as JavaScript, where DOMDocument isn't a universally available option). jQuery, for instance, seems to manage just fine using a regex to convert a HTML string to DOM nodes. Not sure whether or not to CW this, it's a genuine question that I want to be answered and not really intended to be a discussion thread.

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  • Named semaphores in Python?

    - by Boaz
    Hi, I have a script in python which uses a resource which can not be used by more than a certain amount of concurrent scripts running. Classically, this would be solved by a named semaphores but I can not find those in the documentation of the multiprocessing module or threading . Am I missing something or are named semaphores not implemented / exposed by Python? and more importantly, if the answer is no, what is the best way to emulate one? Thanks, Boaz PS. For reasons which are not so relevant to this question, I can not aggregate the task to a continuously running process/daemon or work with spawned processed - both of which, it seems, would have worked with the python API.

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  • Android material L image transition interpolator

    - by Diolor
    This is more of a mathematics question rather than programming. Well, I would like to ask id you know what is the interpolator described in Material design: It looks to be an AccelerateDecelerateInterpolator but the deceleration effect decays slower. My best hatch is : public class MaterialInterpolator implements Interpolator { @Override public float getInterpolation(float input) { if(input<1./3f) return new AccelerateInterpolator().getInterpolation(input); else return new DecelerateInterpolator().getInterpolation(input); } } Which creates a gap between the values: Time / Value 0.3,0.09 0.317,0.100489 0.333,0.110889 <-- gap 0.35,0.57750005 0.367,0.599311 0.383,0.61931103 0.4,0.64 Source: http://www.google.com/design/spec/patterns/imagery-treatment.html

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  • Can you use the PackageMaker command to create an installer from a list of files?

    - by zekel
    I want to (periodically and automatically) create an installer from various files and folders that are in many places. But, I can't figure out how to supply the packagemaker command with all the paths of the items I want to install. This is for internal development purposes, not for customer distribution. I want the files included to be configureable; it's not really an option to use the GUI to add all the paths because they will change frequently. The best I could do was to use the --watch flag and touch all of the stuff I wanted included in the package. This is very messy and includes other files that happen to be accessed at the same time. There isn't a common scheme to what I want to include, so I can't just --filter the rest out. Is there a better way? Am I missing the point?

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  • How do views reduce code duplication?

    - by Debuger
    Hi! I read something like this about db views: Views are incredibly powerful and useful for one reason that stands out above all the other very good reasons. They reduce code duplication. That is, in most cases, the bottom line. If a query will be used in three or more places, then a view will drastically simplify your changes if the schema or query parameters change. I once had to edit 22 stored procedures to change some query logic. If the original architecture had utilized views, then I would have had only three changes. Can anyone explain to me how it works, and maybe give me some examples? Best regards!

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  • How to stop ReSharper from showing error on a lambda expression where Action is expected?

    - by carlmon
    In Silverlight, System.Windows.Threading's Dispatcher.BeginInvoke() takes an Action<T> or a delegate to invoke. .NET allows me to pass just the lambda expression. but ReSharper sees it as an error, saying "Cannot resolve method 'BeginInvoke(lambda expression)'": Dispatcher.BeginInvoke(() => { DoSomething(); }) The error goes away if I explicitly create the Action around the expression like this: Dispatcher.BeginInvoke(new Action<object>(o => { DoSomething(); })); I prefer the least amount of code in this case for the best readability. Is there a way to disable this specific ReSharper error notification? I tried some of the options, but could not find it. Thanks, Carl

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  • Server Benchmarking: What tools to use with my real-world test data

    - by mdemmitt
    I want to benchmark a new server using historical HTTP-request data. I have a textfile that contains one day's worth of real historical requests to a production server. What is the best tool for sending that list of requests on the server I'm testing? The tool I use should be able to configure the following: Number of threads making the requests Number of requests/second sent A list of request URLs to use when making the requests. Apache Bench seems like a close fit. However, Bench does not seem to be able to take in a list of request URLs as a parameter. What would you recommend?

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  • Ouput all the page's media queries in a list

    - by alecrust
    Using JavaScript, what would be the best way to output a list containing all media queries that are being applied to the current page. I assume this would need to filtering to find embedded media queries i.e. <link rel="stylesheet" media="only screen and (min-width: 30em)" href="/css/30em.css"> as well as media queries located in CSS files, i.e. @media only screen and (min-width: 320px) {} An example output of what I'm looking for: <p>There are 3 media queries loaded on this page</p> <ol> <li>30em</li> <li>40em</li> <li>960px</li> </ol>

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