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  • How to define 2-bit numbers in C, if possible?

    - by Eddy
    For my university process I'm simulating a process called random sequential adsorption. One of the things I have to do involves randomly depositing squares (which cannot overlap) onto a lattice until there is no more room left, repeating the process several times in order to find the average 'jamming' coverage %. Basically I'm performing operations on a large array of integers, of which 3 possible values exist: 0, 1 and 2. The sites marked with '0' are empty, the sites marked with '1' are full. Initially the array is defined like this: int i, j; int n = 1000000000; int array[n][n]; for(j = 0; j < n; j++) { for(i = 0; i < n; i++) { array[i][j] = 0; } } Say I want to deposit 5*5 squares randomly on the array (that cannot overlap), so that the squares are represented by '1's. This would be done by choosing the x and y coordinates randomly and then creating a 5*5 square of '1's with the topleft point of the square starting at that point. I would then mark sites near the square as '2's. These represent the sites that are unavailable since depositing a square at those sites would cause it to overlap an existing square. This process would continue until there is no more room left to deposit squares on the array (basically, no more '0's left on the array) Anyway, to the point. I would like to make this process as efficient as possible, by using bitwise operations. This would be easy if I didn't have to mark sites near the squares. I was wondering whether creating a 2-bit number would be possible, so that I can account for the sites marked with '2'. Sorry if this sounds really complicated, I just wanted to explain why I want to do this.

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  • Undefined javascript function?

    - by user74283
    Working on a google maps project and stuck on what seems to be a minor issue. When i call displayMarkers function firebug returns: ReferenceError: displayMarkers is not defined [Break On This Error] displayMarkers(1); <script type="text/javascript"> function initialize() { var center = new google.maps.LatLng(25.7889689, -80.2264393); var map = new google.maps.Map(document.getElementById('map'), { zoom: 10, center: center, mapTypeId: google.maps.MapTypeId.ROADMAP }); //var data = [[25.924292, -80.124314], [26.140795, -80.3204049], [25.7662857, -80.194692]] var data = {"crs": {"type": "link", "properties": {"href": "http://spatialreference.org/ref/epsg/4326/", "type": "proj4"}}, "type": "FeatureCollection", "features": [{"geometry": {"type": "Point", "coordinates": [25.924292, -80.124314]}, "type": "Feature", "properties": {"industry": [2], "description": "hosp", "title": "shaytac hosp2"}, "id": 35}, {"geometry": {"type": "Point", "coordinates": [26.140795, -80.3204049]}, "type": "Feature", "properties": {"industry": [1, 2], "description": "retail", "title": "shaytac retail"}, "id": 48}, {"geometry": {"type": "Point", "coordinates": [25.7662857, -80.194692]}, "type": "Feature", "properties": {"industry": [2], "description": "hosp2", "title": "shaytac hosp3"}, "id": 36}]} var markers = []; for (var i = 0; i < data.features.length; i++) { var latLng = new google.maps.LatLng(data.features[i].geometry.coordinates[0], data.features[i].geometry.coordinates[1]); var marker = new google.maps.Marker({ position: latLng, title: console.log(data.features[i].properties.industry[0]), map: map }); marker.category = data.features[i].properties.industry[0]; marker.setVisible(true); markers.push(marker); } function displayMarkers(category) { var i; for (i = 0; i < markers.length; i++) { if (markers[i].category === category) { markers[i].setVisible(true); } else { markers[i].setVisible(false); } } } } google.maps.event.addDomListener(window, 'load', initialize); </script> <div id="map-container"> <div id="map"></div> </div> <input type="button" value="Retail" onclick="displayMarkers(1);">

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  • Change Sequence to Choice

    - by Gordon
    In my Schema File I defined a Group with a Sequence of possible Elements. <group name="argumentGroup"> <sequence> <element name="foo" type="double" /> <element name="bar" type="string" /> <element name="baz" type="integer" /> </sequence> </group> I then reference this Group like this: <element name="arguments"> <complexType> <group ref="my:argumentGroup"/> </complexType> </element> Is it possible to reference the Group at some other point but restrict it so it's a Choice instead of a Sequence. The position where I want to reuse it would only allow one of the Elements within. <element name="argument" minOccurs="0" maxOccurs="1"> <complexType> <group name="my:argumentGroup"> <! -- Somehow change argumentGroup sequence to choice here --> </group> <complexType> </element>

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  • How can I take advantage of IObservable/IObserver to get rid of my "god object"?

    - by Will
    In a system I'm currently working on, I have many components which are defined as interfaces and base classes. Each part of the system has some specific points where they interact with other parts of the system. For example, the data readying component readies some data which eventually needs to go to the data processing portion, the communications component needs to query different components for their status for relaying to the outside, etc. Currently, I glue these parts of the system together using a "god object", or an object with intimate knowledge of different parts of the system. It registers with events over here and shuttles the results to methods over there, creates a callback method here and returns the result of that method over there, and passes many requests through a multi-threaded queue for processing because it "knows" certain actions have to run on STA threads, etc. While its convenient, it concerns me that this one type knows so much about how everybody else in the system is designed. I'd much prefer a more generic hub that can be given instances which can expose events or methods or callbacks or that can consume these. I've been seeing more about the IObservable/IObserver features of the reactive framework and that are being rolled into .NET 4.0 (I believe). Can I leverage this pattern to help replace my "god object"? How should I go about doing this? Are there any resources for using this pattern for this specific purpose?

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  • Determine if a Range contains a value

    - by Brad Dwyer
    I'm trying to figure out a way to determine if a value falls within a Range in Swift. Basically what I'm trying to do is adapt one of the examples switch statement examples to do something like this: let point = (1, -1) switch point { case let (x, y) where (0..5).contains(x): println("(\(x), \(y)) has an x val between 0 and 5.") default: println("This point has an x val outside 0 and 5.") } As far as I can tell, there isn't any built in way to do what my imaginary .contains method above does. So I tried to extend the Range class. I ended up running into issues with generics though. I can't extend Range<Int> so I had to try to extend Range itself. The closest I got was this but it doesn't work since >= and <= aren't defined for ForwardIndex extension Range { func contains(val:ForwardIndex) -> Bool { return val >= self.startIndex && val <= self.endIndex } } How would I go about adding a .contains method to Range? Or is there a better way to determine whether a value falls within a range? Edit2: This seems to work to extend Range extension Range { func contains(val:T) -> Bool { for x in self { if(x == val) { return true } } return false } } var a = 0..5 a.contains(3) // true a.contains(6) // false a.contains(-5) // false I am very interested in the ~= operator mentioned below though; looking into that now.

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  • Are TestContext.Properties usable ?

    - by DBJDBJ
    Using Visual Studio generate Test Unit class. Then comment in, the class initialization method. Inside it add your property, using the testContext argument. Upon test app startup this method is indeed called by the testing infrastructure. //Use ClassInitialize to run code before running the first test in the class [ClassInitialize()] public static void MyClassInitialize(TestContext testContext) { /* * Any user defined testContext.Properties * added here will be erased after this method exits */ testContext.Properties.Add("key", 1 ) ; // place the break point here } After leaving MyClassInitialize, any properties added by user are lost. Only the 10 "official" ones are left. Actually TestContext gets overwritten, with the inital offical one, each time before each test method is called. It it not overwritten only if user has test initialization method, the changes made over there are passed to the test. //Use TestInitialize to run code before running each test [TestInitialize()]public void MyTestInitialize(){ this.TestContext.Properties.Add("this is preserved",1) ; } This effectively means TestContext.Properties is "mostly" read only, for users. Which is not clearly documented in MSDN. It seems to me this is very messy design+implementation. Why having TestContext.Properties as an collection, at all ? Users can do many other solutions to have class wide initialization. Please discuss. --DBJ

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  • Reflection and Operator Overloads in C#

    - by TenshiNoK
    Here's the deal. I've got a program that will load a given assembly, parse through all Types and their Members and compile a TreeView (very similar to old MSDN site) and then build HTML pages for each node in the TreeView. It basically takes a given assembly and allows the user to create their own MSDN-like library for it for documentation purposes. Here's the problem I've run into: whenever an operator overload is encounted in a defined class, reflection returns that as a "MethodInfo" with the name set to something like "op_Assign" or "op_Equality". I want to be able to capture these and list them properly, but I can't find anything in the MethodInfo object that is returned to accurately identify that I'm looking at an operator. I definitely don't want to just capture everything that starts with "op_", since that will most certainly (at some point) will pick up a method it's not supposed to. I know that other methods and properties that are "special cases" like this one have the "IsSpecialName" property set, but appearantly that's not the case with operators. I've been scouring the 'net and wracking my brain to two days trying to figure this one out, so any help will be greatly appreciated.

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  • How to limit TCP writes to particular size and then block untlil the data is read

    - by ustulation
    {Qt 4.7.0 , VS 2010} I have a Server written in Qt and a 3rd party client executable. Qt based server uses QTcpServer and QTcpSocket facilities (non-blocking). Going through the articles on TCP I understand the following: the original implementation of TCP mentioned the negotiable window size to be a 16-bit value, thus maximum being 65535 bytes. But implementations often used the RFC window-scale-extension that allows the sliding window size to be scalable by bit-shifting to yield a maximum of 1 gigabyte. This is implementation defined. This could have resulted in majorly different window sizes on receiver and sender end as the server uses Qt facilities without hardcoding any window size limit. Client 1st asks for all information it can based on the previous messages from the server before handling the new (accumulating) incoming messages. So at some point Server receives a lot of messages each asking for data of several MB's. This the server processes and puts it into the sender buffer. Client however is unable to handle the messages at the same pace and it seems that client’s receiver buffer is far smaller (65535 bytes maybe) than sender’s transmit window size. The messages thus get accumulated at sender’s end until the sender’s buffer is full too after which the TCP writes on sender would block. This however does not happen as sender buffer is much larger. Hence this manifests as increase in memory consumption on the sender’s end. To prevent this from happening, I used Qt’s socket’s waitForBytesWritten() with timeout set to -1 for infinite waiting period. This as I see from the behaviour blocks the thread writing TCP data until the data has actually been sensed by the receiver’s window (which will happen when earlier messages have been processed by the client at application level). This has caused memory consumption at Server end to be almost negligible. is there a better alternative to this (in Qt) if i want to restrict the memory consumption at server end to say x MB's? Also please point out if any of my understandings is incorrect.

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  • Keeping track of dependency revisions

    - by Samaursa
    I have a project with several dependencies that are in various repositories. Each time I commit changes to my project, I make sure I write the revision numbers of all the dependent repositories so that in the event I ever have to come back to this revision (let's call it 5), I can immediately know which revisions of the dependent repositories revision 5 is guaranteed to work with, update the dependencies to the specified revisions, compile and run the project. So for example if I have: Dep1 @ Revisions 10 Dep2 @ Revisions 20 Dep3 @ Revisions 10 Proj @ Revisions 35 And let's say that when Proj was on revision 17, the Dep1 revision was 5, Dep2 revision was 13 and Dep3 revision was 3. So in my SVN logs, I recorded something like this: !! Works with Dep1 Rev 5, Dep2 Rev 13, Dep3 Rev 3 To me this seems primitive and makes me believe that there is a better way to do it. Now in one of my other questions, Ivy Dependency Manager has been recommended. I have not looked at it in detail yet (seems complicated and yet another thing I must learn). To me it seems like the log of SVN (and Mercurial etc.) could have been split into Log and Dependencies (if any) where the latter could be switched off if there were no dependencies (unless of course I am unaware of an easier/better solution). This would allow for a cleaner log that maybe even warned at each new commit to check the previously defined dependencies again and make sure they have not changed. So, I was wondering how everyone manages this situations and if you have any tips, techniques, programs, suggestions that you can offer. Thank you.

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  • How to take a collection of bytes and pull typed values out of it?

    - by Pat
    Say I have a collection of bytes var bytes = new byte[] {0, 1, 2, 3, 4, 5, 6, 7}; and I want to pull out a defined value from the bytes as a managed type, e.g. a ushort. What is a simple way to define what types reside at what location in the collection and pull out those values? One (ugly) way is to use System.BitConverter and a Queue or byte[] with an index and simply iterate through, e.g.: int index = 0; ushort first = System.BitConverter.ToUint16(bytes, index); index += 2; // size of a ushort int second = System.BitConverter.ToInt32(bytes, index); index += 4; ... This method gets very, very tedious when you deal with a lot of these structures! I know that there is the System.Runtime.InteropServices.StructLayoutAttribute which allows me to define the locations of types inside a struct or class, but there doesn't seem to be a way to import the collection of bytes into that struct. If I could somehow overlay the struct on the collection of bytes and pull out the values, that would be ideal. E.g. Foo foo = (Foo)bytes; // doesn't work because I'd need to implement the implicit operator ushort first = foo.first; int second = foo.second; ... [StructLayout(LayoutKind.Explicit, Size=FOO_SIZE)] public struct Foo { [FieldOffset(0)] public ushort first; [FieldOffset(2)] public int second; } Any thoughts on how to achieve this?

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  • What collection object is appropriate for fixed ordering of values?

    - by makerofthings7
    Scenario: I am tracking several performance counters and have a CounterDescription[] correlate to DataSnapshot[]... where CounterDescription[n] describes the data loaded within DataSnapshot[n]. I want to expose an easy to use API within C# that will allow for the easy and efficient expansion of the arrays. For example CounterDescription[0] = Humidity; DataSnapshot[0] = .9; CounterDescription[1] = Temp; DataSnapshot[1] = 63; My upload object is defined like this: Note how my intent is to correlate many Datasnapshots with a dattime reference, and using the offset of the data to refer to its meaning. This was determined to be the most efficient way to store the data on the back-end, and has now reflected itself into the following structure: public class myDataObject { [DataMember] public SortedDictionary<DateTime, float[]> Pages { get; set; } /// <summary> /// An array that identifies what each position in the array is supposed to be /// </summary> [DataMember] public CounterDescription[] Counters { get; set; } } I will need to expand each of these arrays (float[] and CounterDescription[] ), but whatever data already exists must stay in that relative offset. Which .NET objects support this? I think Array[] , LinkedList<t>, and List<t> Are able to keep the data fixed in the right locations. What do you think?

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  • XML Doc to JSP to TIFF

    - by SPD
    We have around 100 word templates, every time user gets a business request he goes into shared folder select the template he/she wants and enter information and save it as tiff, these tiffs later processed by some batch program. I am trying to automate this process. So I defined an XML which has Template information like <Template id="1"> <Section id="1"> <fieldName id="1">Date</fieldName> <fieldValue></fieldValue> <fieldtype></fieldType> <fieldProperty>textField</fieldProperty> </Section> <Section id="2"> <fieldName id="2">Claim#</fieldName> <fieldValue></fieldValue> <fieldtype></fieldType> <fieldProperty>textField</fieldProperty> </Section> </Template> Based on the template values I generate the JSP on fly. Now I would like to generate a TIFF file out of it in specified format. I am not sure how to handle this requirement. *edited the original question.

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  • Using C struct without including header file

    - by shams
    My basic problem is that I want to use some structs and functions defined in a header file by not including that header file in my code. The header file is generated by a tool. Since I don't have access to the header file, I can't include it in my program. Here's a simple example of my scenario: first.h #ifndef FIRST_H_GUARD #define FIRST_H_GUARD typedef struct ComplexS { float real; float imag; } Complex; Complex add(Complex a, Complex b); // Other structs and functions #endif first.c #include "first.h" Complex add(Complex a, Complex b) { Complex res; res.real = a.real + b.real; res.imag = a.imag + b.imag; return res; } my_program.c // I cannot/do not want to include the first.h header file here // but I want to use the structs and functions from the first.h #include <stdio.h> int main() { Complex a; a.real = 3; a.imag = 4; Complex b; b.real = 6; b.imag = 2; Complex c = add(a, b); printf("Result (%4.2f, %4.2f)\n", c.real, c.imag); return 0; } My intention is to build an executable for my_program and then use the linker to link up the executables. Is what I want to achieve possible in C?

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  • Sharing rails fragments between formats

    - by Julian
    Hi I'm toying with mobile_fu and want to share some fragments between the different views. E.g. views/ item/ view.html.erb view.mobile.rb shared/ _common.erb In both view.html.erb and view.mobile.erb I want to share the same fragment '_common.erb' without having to specify the format (should you ever have to specify the format inside a fragment? It doesn't seem like The Rails Way?). Let's say for arguments's sake it's because it's in a helper or whatever -- the point is that I need to share fragments in a 'well-defined and Railsy way' across formats. Let's take this fairly innocuous snippet <% render :fragment => 'shared/common' %> I've tried 3 file name conventions: _common.html.erb only works for html /item/view/xx fails with 'shared/_common.erb not found') however _common.erb fails for html and works for mobile (maybe mobile_fu is doing something wacky?) -- same error as for .html.erb version above _common.rhtml does work for both I'm thinking that: that rhtml works for both is a legacy hack and I'm loathe to rename all the shared fragments .rhtml to get the behaviour I want. Any feedback gratefully welcome! Including 'you fundamentally don't understand how Rails works please RTFM here: http://....' :)

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  • jQuery code works for console but not in-page.

    - by justSteve
    I have a form element defined as: <div class="field"> <div class="name"> <label for="User_LastName"> Last name: <span class="asterisk">*</span></label> </div> <div class="value"> <%= Html.TextBox("User.LastName", Model.LastName)%> <%= Html.ValidationMessage("User.LastName")%> </div> </div> and a jQuery selector that is supposed to detect when the input gets focus and highlight the parent: $("input").focus(function() { //watching for an event where an input form comes into focus $(this) .parent() .addClass("curFocus") .children("div") .toggle(); }); If i paste this code into firebug's console - things work as planned. However, i'm running this from a 'RenderPartial' .net mvc page. Other jQuery code sitting within the same $(document).ready(function() { block work correctly. The form uses html helpers to generate the inputs which might complicate the process somewhat - but even so... i'm seeing correct behavior when that code's in console but not in a 'real-time' page. How do i troubleshoot this?

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  • How to convert a rectangle to TRBL CSS rect value?

    - by VLostBoy
    I'm not quite sure how to put this, but here goes... The css clip attribute is defined like so: rect(top, right, bottom, left). However, I'm exploring the use of a custom Rectangle 'class' to encapsulate some operations. The rectangle class has the attributes height, width and x, y. The x and y values are encapsulated in a Point object, and the height and width are encapsulated in a Dimension object, the rectangle being a composite of a point (its top-left location) and a dimension (width and height). So far so good. I though it would be pretty simple on the basis of having the rectangles x, y, width and height values to define the css rect attribute in terms of top, right, bottom, left, but I've become hopelessly confused- I've been googling for a while, and I can't seem to find any documentation as to what the TRBL values actually are or what they represent. For example, should I be thinking in terms of co-ordinates, in which case, surely I can describe the rectangle as a css rect using the rectangles x position for Top, x position + width for Right, the rectangles height + y for Bottom and its y position for Left... but thats a load of BS, surely? Also, surely rect is actually an inset, or have I just inverted my understanding of clip? I'd appreciate some advice. What I want to be able to do is (i) Define a rectangle using x, y, width and height (ii)Express the rectangle in TRBL form so that I can manipulate a divs clipping behaviour (iii)Change x, y, width or height and recalculate in terms of TRBL and goto (ii) I appreciate there are some other factors here, and some intermediary transforms to be done, but I've confused myself pretty badly- Can anyone give me some pointers?

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  • initialise a var in scala

    - by user unknown
    I have a class where I like to initialize my var by reading a configfile, which produces intermediate objects/vals, which I would like to group and hide in a method. Here is the bare minimum of the problem - I call the ctor with a param i, in reality a File to parse, and the init-method generates the String s, in reality more complicated than here, with a lot of intermediate objects being created: class Foo (val i: Int) { var s : String; def init () { s = "" + i } init () } This will produce the error: class Foo needs to be abstract, since variable s is not defined. In this example it is easy to solve by setting the String to "": var s = "";, but in reality the object is more complex than String, without an apropriate Null-implementation. I know, I can use an Option, which works for more complicated things than String too: var s : Option [String] = None def init () { s = Some ("" + i) } or I can dispense with my methodcall. Using an Option will force me to write Some over and over again, without much benefit, since there is no need for a None else than to initialize it that way I thought I could. Is there another way to achieve my goal?

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  • JavaScript functions in footer

    - by Djave
    I'm currently using html5 boilerplate, which puts jQuery and your plugins into the footer. The only problem is, I use the same footer.php file in every page. How do I go about including page specific functions if the plugins aren't loaded yet? I.e. <?php include_layout_template('header.php', '../');?> <div id='mediaspace'>This text will be replaced</div> <!-- Video for this page: --> <script type='text/javascript'> jwplayer('mediaspace').setup({ 'flashplayer': '../resources/player.swf', 'file': 'http://content.longtailvideo.com/videos/flvplayer.flv', 'controlbar': 'bottom', 'width': '470', 'height': '320' }); </script> <?php //This file has the jwplayer function in it: include_layout_template('footer.php', '../'); ?> Doing this I get Uncaught ReferenceError: jwplayer is not defined Is it going to be easier to just put the plugin includes in the header? How do people usually tackle stuff like this in boilerplate/loading scripts at the end?

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  • Small Open source and free java applications

    - by user1089770
    I am a Perl Developer who has just stepped into the Java world and I want to be very proficient in Java EE development. However, I have found that, being a Perl guy, I have very high MTI(Mother Tongue Influence). Indians will know what MTI is. For others, it can be defined as an influence of your "main" language whenever you "speak" your new language. In other words, our mind converts/translates what we want to "say" in the new language based on the "main" language, which can be quite absurd or meaning less in the "new" language. Coming back to the point, as a result of this MTI, many lines of my code has this Perl influence and it is absurd and useless for production. Hence, I'd like to see or better do some research on existing small to medium open source java applications, so that I will know how I can "speak" in the native way of the "new" language. Some examples in PHP will be : WordPress, Zend etc. So I'd really appreciate if you guys could suggest any such apps. Apps that have a great commercial value are highly preferred

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  • Signed_request lost in ASP.NET session, confusing my website

    - by Csabi
    I have an ASP.NET MVC 3 website which is available both from a specific public url, and I'm also making be available as a Facebook App. Inside my website logic, in some places I have to determine whether the current request is from the Facebook-app, or from the public website, because I want to display content based on this environment. So, for eg. if the user is using my site as a facebook-app, then I want to display a picture, and if the user is using my site normally, then I don't wanna display a picture. To determine whether I'm from a Facebook app, I check the "signed_request" in the HttpContext.Request, and store it in the HttpSession to be available for my other actions, not just for that action (url) which is defined for my Facebook app. So when a child-action is executed, I can determine based on the Session, that the website is used as a FB-app or not. The problem happens, when the Session times out, because then althought the logic is still running inside Facebook, my logic thinks it's not inside Facebook. Any advice?

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  • Using h:outputFormat to message-format the f:selectItems of a h:selectOneRadio

    - by msharma
    I am having some trouble with using h:selectOneRadio. I have a list of objects which is being returned which needs to be displayed. I am trying something like this: <h:selectOneRadio id="selectPlan" layout="pageDirection"> <f:selectItems value="#{detailsHandler.planList}" /> </h:selectOneRadio> and planList is a List of Plans. Plan is defined as: public class Plan { protected String id; protected String partNumber; protected String shortName; protected String price; protected boolean isService; protected boolean isOption; //With all getters/setters } The text that must appear for each radio button is actually in a properties file, and I need to insert params in the text to fill out some value in the bean. For example the text in my properties file is: plan_price=The price of this plan is {0}. I was hoping to do something like this: <f:selectItems value="<h:outputFormat value="#{i18n.plan_price}"> <f:param value="#{planHandler.price}"> </h:outputFormat>" /> Usually if it's not a h:selectOneRadio component, if it's just text I use the h:outputFormat along with f:param tags to display the messages in my .property file called i18n above, and insert a param which is in the backing bean. here this does not work. Does anyone have any ideas how I can deal with this? I am being returned a list of Plans each with their own prices and the text to be displayed is held in property file. Any help much appreciated. Thanks!

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  • Index question: Select * with WHERE clause. Where and how to create index

    - by Mestika
    Hi, I’m working on optimizing some of my queries and I have a query that states: select * from SC where c_id ="+c_id” The schema of ** SC** looks like this: SC ( c_id int not null, date_start date not null, date_stop date not null, r_t_id int not null, nt int, t_p decimal, PRIMARY KEY (c_id, r_t_id, date_start, date_stop)); My immediate bid on how the index should be created is a covering index in this order: INDEX(c_id, date_start, date_stop, nt, r_t_id, t_p) The reason for this order I base on: The WHERE clause selects from c_id thus making it the first sorting order. Next, the date_start and date_stop to specify a sort of “range” to be defined in these parameters Next, nt because it will select the nt Next the r_t_id because it is a ID for a specific type of my r_t table And last the t_p because it is just a information. I don’t know if it is at all necessary to order it in a specific way when it is a SELECT ALL statement. I should say, that the SC is not the biggest table. I can say how many rows it contains but a estimate could be between <10 and 1000. The next thing to add is, that the SC, in different queries, inserts the data into the SC, and I know that indexes on tables which have insertions can be cost ineffective, but can I somehow create a golden middle way to effective this performance. Don't know if it makes a different but I'm using IBM DB2 version 9.7 database Sincerely Mestika

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  • Obfuscating ids in Rails app

    - by fphilipe
    I'm trying to obfuscate all the ids that leave the server, i.e., ids appearing in URLs and in the HTML output. I've written a simple Base62 lib that has the methods encode and decode. Defining—or better—overwriting the id method of an ActiveRecord to return the encoded version of the id and adjusting the controller to load the resource with the decoded params[:id] gives me the desired result. The ids now are base62 encoded in the urls and the response displays the correct resource. Now I started to notice that subresources defined through has_many relationships aren't loading. e.g. I have a record called User that has_many Posts. Now User.find(1).posts is empty although there are posts with user_id = 1. My explanation is that ActiveRecord must be comparing the user_id of Post with the method id of User—which I've overwritten—instead of comparing with self[:id]. So basically this renders my approach useless. What I would like to have is something like defining obfuscates_id in the model and that the rest would be taken care of, i.e., doing all the encoding/decoding at the appropriate locations and preventing ids to be returned by the server. Is there any gem available or does somebody have a hint how to accomplish this? I bet I'm not the first trying this.

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  • fopen / fopen_s and writing to files

    - by yCalleecharan
    Hi, I'm using fopen in C to write the output to a text file. The function declaration is (where ARRAY_SIZE has been defined earlier): void create_out_file(char file_name[],long double *z1){ FILE *out; int i; if((out = fopen(file_name, "w+")) == NULL){ fprintf(stderr, "* Open error on output file %s", file_name); exit(-1); } for(i = 0; i < ARRAY_SIZE; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } My questions: On compilation with MVS2008 I get the warning: warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. I haven't see much information on fopen_s so that I can change my code. Any suggestions? Can one instruct fprintf to write at desired precision? If I'm using long double then I assume that my answers are good till 15 digits after the decimal point. Am I right? Thanks a lot...

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  • C++ Operator Ambiguity

    - by Scott
    Forgive me, for I am fairly new to C++, but I am having some trouble regarding operator ambiguity. I think it is compiler-specific, for the code compiled on my desktop. However, it fails to compile on my laptop. I think I know what's going wrong, but I don't see an elegant way around it. Please let me know if I am making an obvious mistake. Anyhow, here's what I'm trying to do: I have made my own vector class called Vector4 which looks something like this: class Vector4 { private: GLfloat vector[4]; ... } Then I have these operators, which are causing the problem: operator GLfloat* () { return vector; } operator const GLfloat* () const { return vector; } GLfloat& operator [] (const size_t i) { return vector[i]; } const GLfloat& operator [] (const size_t i) const { return vector[i]; } I have the conversion operator so that I can pass an instance of my Vector4 class to glVertex3fv, and I have subscripting for obvious reasons. However, calls that involve subscripting the Vector4 become ambiguous to the compiler: enum {x, y, z, w} Vector4 v(1.0, 2.0, 3.0, 4.0); glTranslatef(v[x], v[y], v[z]); Here are the candidates: candidate 1: const GLfloat& Vector4:: operator[](size_t) const candidate 2: operator[](const GLfloat*, int) <built-in> Why would it try to convert my Vector4 to a GLfloat* first when the subscript operator is already defined on Vector4? Is there a simple way around this that doesn't involve typecasting? Am I just making a silly mistake? Thanks for any help in advance.

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