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  • C Run-Time library part 2

    - by b-gen-jack-o-neill
    Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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  • Variable amount of columns returned in mysqli prepared statement

    - by manyxcxi
    I have a situation where a dynamic query is being generated that could select anywhere from 1 to over 300 different columns across multiple tables. It currently works fine just doing a query, however the issue I'm running into in using a prepared statement is that I do not know how to handle the fact that I don't know how many columns I will be asking for each time and therefor don't know how to process the results. The reason I believe a bind statement will help is because once this query is run once, it will most likely (though not always) be run again with the exact same parameters. Currently I have something like this: $rows = array(); $this->statement = $this->db->prepare($query); $this->statement->bind_param('i',$id); $this->statement->execute(); $this->statement->bind_result($result); while($this->statement->fetch()) { $rows[] = $result; } I know this doesn't work as I want it to, my question is how do I get the data back out of the query. Is it possible to bring the columns back in an associative array by column name, like a standard mysqli query?

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  • OO Objective-C design with XML parsing

    - by brainfsck
    Hi, I need to parse an XML record that represents a QuizQuestion. The "type" attribute tells the type of question. I then need to create an appropriate subclass of QuizQuestion based on the question type. The following code works ([auto]release statements omitted for clarity): QuizQuestion *question = [[QuizQuestion alloc] initWithXMLString:xml]; if( [ [question type] isEqualToString:@"multipleChoiceQuestion"] ) { [myQuestions addObject:[[MultipleChoiceQuizQuestion alloc] initWithXMLString:xml]; } //QuizQuestion.m -(id)initWithXMLString:(NSString*)xml { self.type = ...// parse "type" attribute from xml // parse the rest of the xml } //MultipleChoiceQuizQuestion.m -(id)initWithXMLString:(NSString*)xml { if( self= [super initWithXMLString:xml] ) { // multiple-choice stuff } } Of course, this means that the XML is parsed twice: once to find out the type of QuizQuestion, and once when the appropriate QuizQuestion is initialized. To prevent parsing the XML twice, I tried the following approach: // MultipleChoiceQuizQuestion.m -(id)initWithQuizRecord:(QuizQuestion*)record { self=record; // record has already parsed the "type" and other parameters // multiple-choice stuff } However, this fails due to the "self=record" assignment; whenever the MultipleChoiceQuizQuestion tries to call an instance-method, it tries to call the method on the QuizQuestion class instead. Can someone tell me the correct approach for parsing XML into the appropriate subclass when the parent class needs to be initialized to know which subclass is appropriate?

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  • How do I simulate "In" using Linq2Sql

    - by flipdoubt
    I often find myself with a list of disconnected Linq2Sql objects or keys that I need to re-select from a Linq2Sql data-context to update or delete in the database. If this were SQL, I would use IN in the SQL WHERE clause, but I am stuck with what to do in Linq2Sql. Here is a sample of what I would like to write: public void MarkValidated(IList<int> idsToValidate) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate).ToList(); foreach(var item in items) item.Validated = DateTime.Now; _Db.SubmitChanges(); } // Disposes of DataContext } Or: public void DeleteItems(IList<int> idsToDelete) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate); _Db.Items.DeleteAllOnSubmit(items); _Db.SubmitChanges(); } // Disposes of DataContext } Can I get this done in one trip to the database? If so, how? Is it possible to send all those ints to the database as a list of parameters and is that more efficient than doing a foreach over the list to select each item one at a time?

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  • Changing variables outside of Scope C#

    - by sam
    Hi, I'm a beginner C# programmer, and to improve my skills I decided to give Project Euler a try. The first problem on the site asks you to find the sum of all the multiples of 3 and 5 under 1000. Since I'm essentially doing the same thing twice, I made a method to multiply a base number incrementally, and add the sum of all the answers togethor. public static int SumOfMultiplication(int Base, int limit) { bool Escape = false; for (int mult = 1; Escape == true; mult++) { int Number = 0; int iSum = 0; Number = Base * mult; if (Number > limit) return iSum; else iSum = iSum + Number; } regardless of what I put in for both parameters, it ALWAYS returns zero. I'm 99% sure it has something to do with the scope of the variables, but I have no clue how to fix it. All help is appreciated. Thanks in advance, Sam

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  • Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

    - by Berlin Brown
    One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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  • Debugging Actionmailer

    - by Trip
    I have actionmailer set up. Emails are not being sent, and no errors. Where can I start my search to debug this? class Notifier < ActionMailer::Base default_url_options[:host] = APP_DOMAIN def email_blast(user, subject, message) subject subject from NOTIFIER_EMAIL recipients user.email sent_on Time.zone.now body :user => user.first_name + ' ' + user.last_name, :message => message end I do get a return in my log that the email was sent, just no actual email goes through. Also the reason, that this is not working is because I switched form a cluster to a solo box and some server settings were overwritten. I suspect that is probably the reason why this is not working. Anyone know what specific server settings I would have to look at ? UPDATE: ActionMailer::Base.delivery_method = :sendmail config.action_mailer.default_url_options = { :host => "75.101.153.93" } I found this in my production.rb . This code was originally here when it worked. Again, I believe that there must be something missing on my server..I did a 'which sendmail' and it returned /usr/bin/sendmail , so I added this : config.action_mailer.raise_delivery_errors = false config.action_mailer.perform_deliveries = true config.action_mailer.sendmail_settings = { :location => '/usr/bin/sendmail', :arguments => '-i -t' } Redeployed, restarted the server, and tested it. No emails were sent. The production.log said something was sent : Processing MediaController#create_a_video (for 173.161.167.41 at 2010-06-03 11:58:13) [GET] Parameters: {"action"=>"create_a_video", "controller"=>"media", "organization_id"=>"470", "_"=>"1275591493194"} Sent mail to [email protected] Rendering media/create_a_video Completed in 128ms (View: 51, DB: 1) | 200 OK [http://invent.hqchannel.com/organizations/470/media/create_a_video?_=1275591493194]

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  • How to pass a function in a function?

    - by SoulBeaver
    That's an odd title. I would greatly appreciate it if somebody could clarify what exactly I'm asking because I'm not so sure myself. I'm watching the Stanford videos on Programming Paradigms(that teacher is awesome) and I'm up to video five when he started doing this: void *lSearch( void* key, void* base, int elemSize, int n, int (*cmpFn)(void*, void*)) Naturally, I thought to myself, "Oi, I didn't know you could declare a function and define it later!". So I created my own C++ test version. int foo(int (*bar)(void*, void*)); int bar(void* a, void* b); int main(int argc, char** argv) { int *func = 0; foo(bar); cin.get(); return 0; } int foo(int (*bar)(void*, void*)) { int c(10), d(15); int *a = &c; int *b = &d; bar(a, b); return 0; } int bar(void* a, void* b) { cout << "Why hello there." << endl; return 0; } The question about the code is this: it fails if I declare function int *bar as a parameter of foo, but not int (*bar). Why!? Also, the video confuses me in the fact that his lSearch definition void* lSearch( /*params*/ , int (*cmpFn)(void*, void*)) is calling cmpFn in the definition, but when calling the lSearch function lSearch( /*params*/, intCmp ); also calls the defined function int intCmp(void* elem1, void* elem2); and I don't get how that works. Why, in lSearch, is the function called cmpFn, but defined as intCmp, which is of type int, not int* and still works? And why does the function in lSearch not have to have defined parameters?

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  • About redirected stdout in System.Diagnostics.Process

    - by sforester
    I've been recently working on a program that convert flac files to mp3 in C# using flac.exe and lame.exe, here are the code that do the job: ProcessStartInfo piFlac = new ProcessStartInfo( "flac.exe" ); piFlac.CreateNoWindow = true; piFlac.UseShellExecute = false; piFlac.RedirectStandardOutput = true; piFlac.Arguments = string.Format( flacParam, SourceFile ); ProcessStartInfo piLame = new ProcessStartInfo( "lame.exe" ); piLame.CreateNoWindow = true; piLame.UseShellExecute = false; piLame.RedirectStandardInput = true; piLame.RedirectStandardOutput = true; piLame.Arguments = string.Format( lameParam, QualitySetting, ExtractTag( SourceFile ) ); Process flacp = null, lamep = null; byte[] buffer = BufferPool.RequestBuffer(); flacp = Process.Start( piFlac ); lamep = new Process(); lamep.StartInfo = piLame; lamep.OutputDataReceived += new DataReceivedEventHandler( this.ReadStdout ); lamep.Start(); lamep.BeginOutputReadLine(); int count = flacp.StandardOutput.BaseStream.Read( buffer, 0, buffer.Length ); while ( count != 0 ) { lamep.StandardInput.BaseStream.Write( buffer, 0, count ); count = flacp.StandardOutput.BaseStream.Read( buffer, 0, buffer.Length ); } Here I set the command line parameters to tell lame.exe to write its output to stdout, and make use of the Process.OutPutDataRecerved event to gather the output data, which is mostly binary data, but the DataReceivedEventArgs.Data is of type "string" and I have to convert it to byte[] before put it to cache, I think this is ugly and I tried this approach but the result is incorrect. Is there any way that I can read the raw redirected stdout stream, either synchronously or asynchronously, bypassing the OutputDataReceived event? PS: the reason why I don't use lame to write to disk directly is that I'm trying to convert several files in parallel, and direct writing to disk will cause severe fragmentation. Thanks a lot!

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  • How can I have a VBA macro perform a Search/Replace in formulas across an entire workbook?

    - by richardtallent
    I distribute an Excel workbook to a number of users, and they are supposed to have a particular macro file pre-installed in their XLSTART folder. If they don't have the macro installed correctly, and they send the workbook back to me, any formulas depending on it include the full path of the macro, e.g.: 'C:\Documents and Settings\richard.tallent\Application Data\ Microsoft\Excel\XLSTART\pcs.xls'!MyMacroFunction() I want to create a quick macro I can use to remove the improper path from every formula in the workbook. I've successfully retrieved the special folder using GetSpecialFolder (an external function that is working just fine), but the Replace call itself shown below throws an "Application-defined or object-defined error". Public Sub FixBrokenMacroFormulas() Dim badpath As String badpath = "'" & GetSpecialFolder(AppDataFolder) & "\Microsoft\Excel\XLSTART\mymacro.xls'!" Dim Sheet As Worksheet For Each Sheet In ActiveWorkbook.Sheets Call Sheet.Activate Call Sheet.Select(True) Call Selection.Replace(What:=badpath, Replacement:="", LookIn:=xlFormulas) ''//LookAt:=xlPart, MatchCase:=False, SearchFormat:=False, ReplaceFormat:=False Next End Sub Automating search and replace isn't exactly my forte, what am I doing wrong? I've already commented out some of the parameters that don't seem essential.

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  • UriMapper Problem

    - by jsop
    I have the following xaml (nonessential markup removed in the interest of brevity): <navigation:Frame x:Name="ContentFrame" > <navigation:Frame.UriMapper> <uriMapper:UriMapper> <uriMapper:UriMapping Uri="/{pageName}" MappedUri="/Views/{pageName}.xaml"/> <uriMapper:UriMapping Uri="/FMChart/{metricID}/{orgID}" MappedUri="/Views/FMChart.xaml?metricID={metricID}&orgID={orgID}"/> </navigation:Frame.UriMapper> </navigation:Frame.UriMapper> </navigation:Frame> I'm creating the HyperLinkButton objects dynamically (in code), like so: int metricID = 1; int orgID = 1; HyperlinkButton button = new HyperlinkButton(); button.Name = Guid.NewGuid().ToString(); button.TargetName = "ContentFrame"; // this string doesn't work string url = string.Format("/FMChart/{0}/{1}", metricID, orgID); button.NavigateUri = new Uri(url, UriKind.Relative); When I click the bbutton, the browser renders a blank page, and eventually presents me with a REALLY long stack trace (InvalidOperation exception). If I take the parameters out of th indicated line: string url = "/FMChart"; ...it works as expected (brings up the desired page). I've also tried the following strings: /FMChart/{0}&{1} /FMChart/{0}& amp;{1} What am I doing wrong?

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  • Get Function Pointer to function in a shared library I didn't directly load

    - by bdk
    My Linux application (A) links against a Third Party shared Library (B) which I don't have source code to. This library makes use of another third party shared library that I don't have source code to (C). I believe that (B) uses dlopen to access (C) instead of directly linking. My reasoning for this is that 'ldd' on (B) does not show (C) and objdump -X (B) shows references to dlopen/dlclose/dlsym. My requirement is that I need to in my code for (A) get a function pointer to a function foo() located in (C). Normally I'd use dlsym for this, but I need to pass it the handle returned from dlopen which I don't have since (B) does not expose this. - For the larger context: I need to modify the function in (C) such that everytime it calls its helper function bar() (also located in (C)), it also calls a function with the same signature located in (A) with the same parameters (Basically inject my code into the codepath of (C) foo()-bar(). I believe I've found a way to accomplish this using gdb, but in order to port my gdb command list, but I'm stuck on the step of getting the function pointer. I'm also open to alternatives to accomplish the same task rather than the exact problem as stated above Edit: After writing this I realized I can probably just do another dlopen on the file in my code and the symbols returned via dlsym on that handle should be the same as received via the original dlopen, If I'm reading the dlopen man page correctly. However I'm still interested in advice or assistance with the my larger context, If theres a better way to go about this

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  • Ordering by formula fields in NHibernate

    - by Darin Dimitrov
    Suppose that I have the following mapping with a formula property: <class name="Planet" table="planets"> <id name="Id" column="id"> <generator class="native" /> </id> <!-- somefunc() is a native SQL function --> <property name="Distance" formula="somefunc()" /> </class> I would like to get all planets and order them by the Distance calculated property: var planets = session .CreateCriteria<Planet>() .AddOrder(Order.Asc("Distance")) .List<Planet>(); This is translated to the following query: SELECT Id as id0, somefunc() as formula0 FROM planets ORDER BY somefunc() Desired query: SELECT Id as id0, somefunc() as formula0 FROM planets ORDER BY formula0 If I set a projection with an alias it works fine: var planets = session .CreateCriteria<Planet>() .SetProjection(Projections.Alias(Projections.Property("Distance"), "dist")) .AddOrder(Order.Asc("dist")) .List<Planet>(); SQL: SELECT somefunc() as formula0 FROM planets ORDER BY formula0 but it populates only the Distance property in the result and I really like to avoid projecting manually over all the other properties of my object (there could be many other properties). Is this achievable with NHibernate? As a bonus I would like to pass parameters to the native somefunc() SQL function. Anything producing the desired SQL is acceptable (replacing the formula field with subselects, etc...), the important thing is to have the calculated Distance property in the resulting object and order by this distance inside SQL.

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  • C/C++ Control Structure Limitations?

    - by STingRaySC
    I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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  • MySQL: Complex Join Statement involving two tables and a third correlation table

    - by Stephen
    I have two tables that were built for two disparate systems. I have records in one table (called "leads") that represent customers, and records in another table (called "manager") that are the exact same customers but "manager" uses different fields (For example, "leads" contains an email address, and "manager" contains two fields for two different emails--either of which might be the email from "leads"). So, I've created a correlation table that contains the lead_id and manager_id. currently this correlation table is empty. I'm trying to query the "leads" table to give me records that match either "manager" email field with the single "leads" email field, while at the same time ignoring fields that have already been added to the "correlated" table. (this way I can see how many leads that match have not yet been correlated.) Here's my current, invalid SQL attempt: SELECT leads.id, manager.id FROM leads, manager LEFT OUTER JOIN correlation ON correlation.lead_id = leads.id WHERE correlation.id IS NULL AND leads.project != "someproject" AND (manager.orig_email = leads.email OR manager.dest_email = leads.email) AND leads.created BETWEEN '1999-01-01 00:00:00' AND '2010-05-10 23:59:59' ORDER BY leads.created ASC; I get the error: Unknown column 'leads.id' in 'on clause' Before you wonder: there are records in the "leads" table where leads.project != "someproject" and leads.created falls between those dates. I've included those additional parameters for completeness.

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  • NetBeans parameter fill after code completion

    - by byte
    This is a particularly annoying problem I'm having, and I can't be the only one to have issue with it. In NetBeans, when you type part of a method, then hit CTRL-SPACE, it displays the code-completion popup, whereupon you can hit tab to finish out the word. This is great, and pretty much how all IDE's operate. Example: Thread.sl < CTRL-SPACE Thread.sleep Yay! Problem is that in this context, once you type in a paren, it auto-fills the parameters for the method with their default names, and inserts a closing paren (regardless of whether you have disabled the option to automatically close them on the preferences page for code completion). This behavior is NOT present if you had manually typed out the full name. How is this helpful to anyone? You've got to type over it your actual variable that you will be passing, and NetBeans gives you no option to prevent the closing paren on code-completion. Does anyone have a way to solve this issue, without having to dive into the netbeans source and build it just for this minor of an issue?

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  • Set Custom ASP.NET UserControl variables when its in a Repeater

    - by tnriverfish
    <%@ Register Src="~/Controls/PressFileDownload.ascx" TagName="pfd" TagPrefix="uc1" %> <asp:Repeater id="Repeater1" runat="Server" OnItemDataBound="RPTLayer_OnItemDataBound"> <ItemTemplate> <asp:Label ID="LBLHeader" Runat="server" Visible="false"></asp:Label> <asp:Image ID="IMGThumb" Runat="server" Visible="false"></asp:Image> <asp:Label ID="LBLBody" Runat="server" class="layerBody"></asp:Label> <uc1:pfd ID="pfd1" runat="server" ShowContainerName="false" ParentContentTypeId="55" /> <asp:Literal ID="litLayerLinks" runat="server"></asp:Literal> </ItemTemplate> </asp:Repeater> System.Web.UI.WebControls.Label lbl; System.Web.UI.WebControls.Literal lit; System.Web.UI.WebControls.Image img; System.Web.UI.WebControls.HyperLink hl; System.Web.UI.UserControl uc; I need to set the ParentItemID variable for the uc1:pdf listed inside the repeater. I thought I should be able to find uc by looking in the e.Item and then setting it somehow. I think this is the part where I'm missing something. uc = (UserControl)e.Item.FindControl("pfd1"); if (uc != null) { uc.Attributes["ParentItemID"] = i.ItemID.ToString(); } Any thoughts would be appreciated. Also tried this with similar results... when I debug inside my usercontrol (pfd1) the parameters I am trying to set have not been set. uc = (UserControl)e.Item.FindControl("pfd1"); if (uc != null) { uc.Attributes.Add("ContainerID", _cid.ToString()); uc.Attributes.Add("ParentItemId", i.ItemID.ToString()); }

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  • jQuery AJAX request (Rails 3) gets redirected and returns empty message body!

    - by elsurudo
    I'm trying to do a manual jQuery AJAX request the following way: $("#user_plan_id").change(function() { $("#plan_container").load('/plans/' + this.value); }); I have the "rails.js" file included in my header, and a "<%= csrf_meta_tag %". I see from my log that the request IS getting to the server (although without the authenticity token... does rails.js even do this?), but the response is a 302 (Found) rather than 200, and no data actually gets rendered. Any ideas? Edit: I now see that the first request redirects, and the proper partial gets rendered on the redirect. However, the 2nd response's body (on the client-side) is still empty. I'm guessing jQuery uses the first response and doesn't have a listener set up for the redirect. How do I get around this? Also, another note: the page doing the requesting is an HTTPS page. Here is what my log says: Started GET "/plans/221168073" for 127.0.0.1 at Tue Jun 15 01:24:06 -0400 2010 Processing by PlansController#show as HTML Parameters: {"id"=>"221168073"} DEPRECATION WARNING: Using #request_uri is deprecated. Use fullpath instead. (called from ensure_proper_protocol at /Users/ernestsurudo/Sites/vidfolia/vendor/plugins/ssl_requirement/lib/ssl_requirement.rb:57) Redirected to http://vidfolia.com/plans/221168073 Completed 302 Found in 1ms Perhaps it has something to do with the deprecation warning?

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  • Help for Platform plus Plugin development by J2ee

    - by echo
    Hi, everybody. I want to develop a monitor platform which can monitor many different subjects such as database, OS, middle ware etc. The system includes two parts: 1. Report center(Show some useful chart and report) 2. Collector(Collect information from monitored subject) For the time being, I just want to monitor some parameters of oracle and Linux. And I will add more monitor subject like MS SqlServer, IBM Db2 ect. later. I need a good architecture so I can easily add new monitor module and not to disturb original framework too much. I want to develop it by the method of “Platform + plugin”. A plugin should have its own UI, setting part and something else. I plan to use struts2 + spring + hibernate to develop report center. I am not very sure how to do design this architecture for I have any “Platform + plugin” experience. I ever googled some information such as OSGI and Portlet. I am not sure which one should be my best choice. Can anyone give me some instruction about it. Your help will be appreciated.

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  • Write a program which works out which is the lowest priced computer in an ArrayList of computer obje

    - by Eoin
    Hello everybody! I am trying to study some java and cannot get my head around this question! Any help would be really appreciated and would help me in further studies! Thank you so much in advance! Eoin from Dublin, Ireland. ArrayList of Objects Write a program which works out which is the lowest priced computer in an ArrayList of computer objects. You should have two classes, one called ComputerTest, and the other called Computer. In the ComputerTest class you should: Have a main method which declares an ArrayList of type Computer called computerList, each element of which represents a computer. Initialise the first three entries of the ArrayList Call a static method which prints out the lowest price computer, called lowestPrice The parameter of this method is (i) an ArrayList of type Computer i.e. ArrayList data Sample output: The lowest priced computer is the Cheapo400 at 399 euro. The Computer class should have: Private instance variables: manufacturer, model, price and quality. Quality is a rating from 1 to 10. public get and set methods to retrieve and set/change the value of the four instance variables a default constructor a constructor that takes four parameters

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  • Ruby on rails form variables as array items

    - by Francois
    I have a simple form with text input and text area, but when I submit it the variables seems to be array items instead of just string values? the form <%= form_tag(home_kontak_path, :remote => true) do %> <label>Jou epos adres</label> <%= text_field(:epos, "", :placeholder => "Jou epos adres", :id => "epos", :class => "input-block-level") %> <label>Boodskap hier</label> <%= text_area(:boodskap, "", :rows => "5", :placeholder => "Boodskap hier...", :id => "boodskap", :class => "input-block-level") %> <%= submit_tag "submit" %> <% end %> console output Started POST "/home/kontak" for 127.0.0.1 at 2012-11-23 11:53:03 +0200 Processing by HomeController#kontak as JS Parameters: {"utf8"=>"?", "authenticity_token"=>"i+5UWaQeBu7LYGPFBNAbum+67VzyyC82JN2wMlLc/UU=", "epos"=>["text box value"], "boodskap"=>["text area value"], "commit"=>""} what i would like it to be instead of "epos"=["text box value"] i want it to return "epos"="text box value"

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  • Why does adding Crossover to my Genetic Algorithm give me worse results?

    - by MahlerFive
    I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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  • What's the best way to retrieve two pieces of data from an XML file?

    - by Morinar
    I've got an XML document that is in either a pre or post FO transformed state that I need to extract some information from. In the pre-case, I need to pull out two tags that represent the pageWidth and pageHeight and in the post case I need to extract the page-height and page-width parameters from a specific tag (I forget which one it is off the top of my head). What I'm looking for is an efficient/easily maintainable way to grab these two elements. I'd like to only read the document a single time fetching the two things I need. I initially started writing something that would use BufferedReader + FileReader, but then I'm doing string searching and it gets messy when the tags span multiple lines. I then looked at the DOMParser, which seems like it would be ideal, but I don't want to have to read the entire file into memory if I could help it as the files could potentially be large and the tags I'm looking for will nearly always be close to the top of the file. I then looked into SAXParser, but that seems like a big pile of complicated overkill for what I'm trying to accomplish. Anybody have any advice? Or simple implementations that would accomplish my goal? Thanks.

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  • How to define a "complicated" ComputedColumn in SQL Server?

    - by Slauma
    SQL Server Beginner question: I'm trying to introduce a computed column in SQL Server (2008). In the table designer of SQL Server Management Studio I can do this, but the designer only offers me one single edit cell to define the expression for this column. Since my computed column will be rather complicated (depending on several database fields and with some case differentiations) I'd like to have a more comfortable and maintainable way to enter the column definition (including line breaks for formatting and so on). I've seen there is an option to define functions in SQL Server (scalar value or table value functions). Is it perhaps better to define such a function and use this function as the column specification? And what kind of function (scalar value, table value)? To make a simplified example: I have two database columns: DateTime1 (smalldatetime, NULL) DateTime2 (smalldatetime, NULL) Now I want to define a computed column "Status" which can have four possible values. In Dummy language: if (DateTime1 IS NULL and DateTime2 IS NULL) set Status = 0 else if (DateTime1 IS NULL and DateTime2 IS NOT NULL) set Status = 1 else if (DateTime1 IS NOT NULL and DateTime2 IS NULL) set Status = 2 else set Status = 3 Ideally I would like to have a function GetStatus() which can access the different column values of the table row which I want to compute the value of "Status" for, and then only define the computed column specification as GetStatus() without parameters. Is that possible at all? Or what is the best way to work with "complicated" computed column definitions? Thank you for tips in advance!

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  • How Does One Make Scala Control Abstraction in Repeat Until?

    - by peter_pilgrim
    Hi I am Peter Pilgrim. I watched Martin Odersky create a control abstraction in Scala. However I can not yet seem to repeat it inside IntelliJ IDEA 9. Is it the IDE? package demo class Control { def repeatLoop ( body: = Unit ) = new Until( body ) class Until( body: = Unit ) { def until( cond: = Boolean ) { body; val value: Boolean = cond; println("value="+value) if ( value ) repeatLoop(body).until(cond) // if (cond) until(cond) } } def doTest2(): Unit = { var y: Int = 1 println("testing ... repeatUntil() control structure") repeatLoop { println("found y="+y) y = y + 1 } { until ( y < 10 ) } } } The error message reads: Information:Compilation completed with 1 error and 0 warnings Information:1 error Information:0 warnings C:\Users\Peter\IdeaProjects\HelloWord\src\demo\Control.scala Error:Error:line (57)error: Control.this.repeatLoop({ scala.this.Predef.println("found y=".+(y)); y = y.+(1) }) of type Control.this.Until does not take parameters repeatLoop { In the curried function the body can be thought to return an expression (the value of y+1) however the declaration body parameter of repeatUntil clearly says this can be ignored or not? What does the error mean?

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