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• How to combine a list of choices to determine which select statement

  - by Larry

  I have a mysql db and am using php 5.2 What I am trying to do is offer a list of options for a person to select (only 1). The chosen option will cause a select, update, or delete statement to be ran. The results of the statement do not need to be shown, although, showing the old and then the new would be nice (no problems with that part tho'.). Pseudo-Code: Assign $choice = 0 Check the value of $choice // This way, if it = 100, we do a break Select a Choice:<br> 1. Adjust Status Value (+60) // $choice = 1<br> 2. Show all Ships <br> // $choice = 2 3. Show Ships in Port <br> // $choice = 3 ... 0. $choice="100" // if the value =100, quit this part Use either case (switch) or if/else statements to run the users choice1 If the choice is 1, then run the "Select" statement with the variable of $sql1 -- "SELECT .... If the choice is 2, then run the "Select" statement with the variable of $sql2 --- SELECT * FROM Ships If the choice is 3, then run the "Select" statement with the variable of $sql3 <br> .... If the choice is 0, then we are done. I figured the (3) statements would be assigned in php as: $sql1="...". $sql2="SELECT * FROM Ships" $sql3="SELECT * FROM Ships WHERE nPort="1" My idea was to use the switch statement, but got lost on it. :( I would like the options to be available over and over again, until a variable ($choice) is selected. In which case, this particular page is done and goes back to the "Main Menu"? The coding and display, if I use it, I can do. Just not sure how to write the way to select which one I want. It is possible that I would run all of the queries, and other times, only one, so that is why I would like the choice. An area I get confused in is the proper forms to use such as -- ' ' " " and ...?? Not sure the # of options I will end up with, but it will be more than 5 but less than 20 / page. So if I get the system down for 2-3 choices, I can replicate it for as many as I may need. And, as always, if a better way exists, I am willing to try it. Thanks again... Larry

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• Bind Config section to DataTable using c#

  - by srk

  I have the following config section in my app.config file and the code to iterate through config section to retrieve the values. But i want to save the values of config section to a datatable in a proper structure. How ? I want to show all the values in datagridview with appropriate columns. <configSections> <section name="ServerInfo" type="System.Configuration.IConfigurationSectionHandler" /> </configSections> <ServerInfo> <Server id="1"> <Name>SRUAV1</Name> <key> 1 </key> <IP>10.1.150.110</IP> <Port>7901</Port> </Server> <Server id="2"> <Name>SRUAV2</Name> <key> 4 </key> <IP>10.1.150.110</IP> <Port>7902</Port> </Server> <Server id="3"> <Name>SRUAV3</Name> <key> 6 </key> <IP>10.1.150.110</IP> <Port>7904</Port> </Server> </ServerInfo> Code : public void GetServerValues(string strSelectedServer) { Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None); ConfigurationSection section = config.GetSection("ServerInfo"); XmlDocument xml = new XmlDocument(); xml.LoadXml(section.SectionInformation.GetRawXml()); string temp = ""; XmlNodeList applicationList = xml.DocumentElement.SelectNodes("Server"); for (int i = 0; i < applicationList.Count; i++) { object objAppId = applicationList[i].Attributes["id"]; int iAppId = 0; if (objAppId != null) { iAppId = Convert.ToInt32(applicationList[i].Attributes["id"].Value); } temp = BuildServerValues(applicationList[i]); } } public string BuildServerValues(XmlNode applicationNode) { for (int i = 0; i < applicationNode.ChildNodes.Count; i++) { if (applicationNode.ChildNodes.Item(i).Name.ToString().Equals("Name")) { strServerName = applicationNode.ChildNodes.Item(i).InnerXml.ToString(); } if (applicationNode.ChildNodes.Item(i).Name.ToString().Equals("IP")) { strIP = applicationNode.ChildNodes.Item(i).InnerXml.ToString(); } if (applicationNode.ChildNodes.Item(i).Name.ToString().Equals("Port")) { strPort = applicationNode.ChildNodes.Item(i).InnerXml.ToString(); } } return strServerName; }

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• SQL Server architecture guidance

  - by Liam

  Hi, We are designing a new version of our existing product on a new schema. Its an internal web application with possibly 100 concurrent users (max)This will run on a SQL Server 2008 database. On of the discussion items recently is whether we should have a single database of split the database for performance reasons across 2 separate databases. The database could grow anywhere from 50-100GB over 5 years. We are Developers and not DBAs so it would be nice to get some general guidance. [I know the answer is not simple as it depends on the schema, archiving policy, amount of data etc. ] Option 1 Single Main Database [This is my preferred option]. The plan would be to have all the tables in a single database and possibly to use file groups and partitioning to separate the data if required across multiple disks. [Use schema if appropriate]. This should deal with the performance concerns One of the comments wrt this was that the a single server instance would still be processing this data so there would still be a processing bottle neck. For reporting we could have a separate reporting DB but this is still being discussed. Option 2 Split the database into 2 separate databases DB1 - Customers, Accounts, Customer resources etc DB2 - This would contain the bulk of the data [i.e. Vehicle tracking data, financial transaction tables etc]. These tables would typically contain a lot of data. [It could reside on a separate server if required] This plan would involve keeping the main data in a smaller database [DB1] and retaining the [mainly] read only transaction type data in a separate DB [DB2]. The UI would mainly read from DB1 and thus be more responsive. [I'm aware that this option makes it harder for Referential Integrity to be enforced.] Points for consideration As we are at the design stage we can at least make proper use of indexes to deal performance issues so thats why option 1 to me is attractive and its more of a standard approach. For both options we are considering implementing an archiving database. Apologies for the long Question. In summary the question is 1 DB or 2? Thanks in advance, Liam

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• NHibernate Many-to-Many Mapping not working

  - by ClutchDude

  I have a Nhibernate mapping file for a simple user/role mapping. Here are the mapping files: Users.hbm.xml <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Sample.Persistence" namespace="Sample.Persistence.Model"> <class name="User" table="Users"> <id name="UserKey"> <generator class="identity"/> </id> <property name="UserName" column="UserName" type="String" /> <property name="Password" column="Password" type="Byte[]" /> <property name="FirstName" column="FirstName" type="String" /> <property name="LastName" column="LastName" type="String" /> <property name="Email" column="Email" type="String" /> <property name="Active" column="Active" type="Boolean" /> <property name="Locked" column="Locked" type="Boolean" /> <property name="LoginFailures" column="LoginFailures" type="int" /> <property name="LockoutDate" column="LockoutDate" type="DateTime" generated="insert" /> <property name="Expired" column="Expired" type="Boolean" generated="insert"/> <set name="Roles" table="UsersRolesBridge" lazy="false"> <key column="UserKey" /> <many-to-many class="Role" not-found="exception" column="RoleKey" /> </set> </class> </hibernate-mapping> Role.hbm.xml <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Sample.Persistence" namespace="Sample.Persistence.Model"> <class name="Role" table="Roles"> <id name="RoleKey"> <generator class="identity"/> </id> <property name="Name" column="Name" type="String" /> <set name="Users" inverse="true" atable="UsersRolesBridge" lazy="false" > <key column="RoleKey" /> <many-to-many class="User" column="UserKey" /> </set> </class> </hibernate-mapping> I am able to retrieve roles for each user via NHibernate but when I go to save a new object, the roles are not saved in the Bridge table. The user is created and insert with no issues. I've checked that the Role collection, a field on the user, is being populated with the proper rolekey before the Session.Save() is called. There is no exception thrown as well.

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• Methodology for a Rails app

  - by Aaron Vegh

  I'm undertaking a rather large conversion from a legacy database-driven Windows app to a Rails app. Because of the large number of forms and database tables involved, I want to make sure I've got the right methodology before getting too far. My chief concern is minimizing the amount of code I have to write. There are many models that interact together, and I want to make sure I'm using them correctly. Here's a simplified set of models: class Patient < ActiveRecord::Base has_many :PatientAddresses has_many :PatientFileStatuses end class PatientAddress < ActiveRecord::Base belongs_to :Patient end class PatientFileStatus < ActiveRecord::Base belongs_to :Patient end The controller determines if there's a Patient selected; everything else is based on that. In the view, I will be needing data from each of these models. But it seems like I have to write an instance variable in my controller for every attribute that I want to use. So I start writing code like this: @patient = Patient.find(session[:patient]) @patient_addresses = @patient.PatientAddresses @patient_file_statuses = @patient.PatientFileStatuses @enrollment_received_when = @patient_file_statuses[0].EnrollmentReceivedWhen @consent_received = @patient_file_statuses[0].ConsentReceived @consent_received_when = @patient_file_statuses[0].ConsentReceivedWhen The first three lines grab the Patient model and its relations. The next three lines are examples of my providing values to the view from one of those relations. The view has a combination of text fields and select fields to show the data above. For example: <%= select("patientfilestatus", "ConsentReceived", {"val1"="val1", "val2"="val2", "Written"="Written"}, :include_blank=true )% <%= calendar_date_select_tag "patient_file_statuses[EnrollmentReceivedWhen]", @enrollment_complete_when, :popup=:force % (BTW, the select tag isn't really working; I think I have to use collection_select?) My questions are: Do I have to manually declare the value of every instance variable in the controller, or can/should I do it within the view? What is the proper technique for displaying a select tag for data that's not the primary model? When I go to save changes to this form, will I have to manually pick out the attributes for each model and save them individually? Or is there a way to name the fields such that ActiveRecord does the right thing? Thanks in advance, Aaron.

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• emacs: how do I use edebug on code that is defined in a macro?

  - by Cheeso

  I don't even know the proper terminology for this lisp syntax, so I don't know if the words I'm using to ask the question, make sense. But the question makes sense, I'm sure. So let me just show you. cc-mode (cc-fonts.el) has things called "matchers" which are bits of code that run to decide how to fontify a region of code. That sounds simple enough, but the matcher code is in a form I don't completely understand, with babckticks and comma-atsign and just comma and so on, and furthermore it is embedded in a c-lang-defcost, which itself is a macro. And I want to run edebug on that code. Look: (c-lang-defconst c-basic-matchers-after "Font lock matchers for various things that should be fontified after generic casts and declarations are fontified. Used on level 2 and higher." t `(;; Fontify the identifiers inside enum lists. (The enum type ;; name is handled by `c-simple-decl-matchers' or ;; `c-complex-decl-matchers' below. ,@(when (c-lang-const c-brace-id-list-kwds) `((,(c-make-font-lock-search-function (concat "\\<\\(" (c-make-keywords-re nil (c-lang-const c-brace-id-list-kwds)) "\\)\\>" ;; Disallow various common punctuation chars that can't come ;; before the '{' of the enum list, to avoid searching too far. "[^\]\[{}();,/#=]*" "{") '((c-font-lock-declarators limit t nil) (save-match-data (goto-char (match-end 0)) (c-put-char-property (1- (point)) 'c-type 'c-decl-id-start) (c-forward-syntactic-ws)) (goto-char (match-end 0))))))) I am reading up on lisp syntax to figure out what those things are and what to call them, but aside from that, how can I run edebug on the code that follows the comment that reads ;; Fontify the identifiers inside enum lists. ? I know how to run edebug on a defun - just invoke edebug-defun within the function's definition, and off I go. Is there a corresponding thing I need to do to edebug the cc-mode matcher code forms?

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• MATLAB arbitrary code execution

  - by aristotle2600

  I am writing an automatic grader program under linux. There are several graders written in MATLAB, so I want to tie them all together and let students run a program to do an assignment, and have them choose the assignment. I am using a C++ main program, which then has mcc-compiled MATLAB libraries linked to it. Specifically, my program reads a config file for the names of the various matlab programs, and other information. It then uses that information to present choices to the student. So, If an assignment changes, is added or removed, then all you have to do is change the config file. The idea is that next, the program invokes the correct matlab library that has been compiled with mcc. But, that means that the libraries have to be recompiled if a grader gets changed. Worse, the whole program must be recompiled if a grader is added or removed. So, I would like one, simple, unchanging matlab library function to call the grader m-files directly. I currently have such a library, that uses eval on a string passed to it from the main program. The problem is that when I do this, apparently, mcc absorbs the grader m-code into itself; changing the grader m code after compilation has no effect. I would like for this not to happen. It was brought to my attention that Mathworks may not want me to be able to do this, since it could bypass matlab entirely. That is not my intention, and I would be happy with a solution that requires a full matlab install. My possible solutions are to use a mex file for the main program, or have the main program call a mcc library, which then calls a mex file, which then calls the proper grader. The reason I am hesitant about the first solution is that I'm not sure how many changes I would have to make to my code to make it work; my code is C++, not C, which I think makes things more complicated. The 2nd solution, though, may just be more complicated and ultimately have the same problem. So, any thoughts on this situation? How should I do this?

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• Rails 3: How do I call a javascript function from a js.erb file

  - by user321775

  Now that I've upgraded to Rails 3, I'm trying to figure out the proper way to separate and reuse pieces of javascript. Here's the scenario I'm dealing with: I have a page with two areas: one with elements that should be draggable, the other with droppables. When the page loads I use jQuery to setup the draggables and droppables. Currently I have the script in the head portion of application.html.erb, which I'm sure is not the right solution but at least works. When I press a button on the page, an ajax call is made to my controller that replaces the draggables with a new set of elements that should also be draggable. I have a js.erb file that renders a partial in the correct location. After rendering I need to make the new elements draggable, so I'd like to reuse the code that currently lives in application.html.erb, but I haven't found the right way to do it. I can only make the new elements draggable by pasting the code directly into my js.erb file (yuck). What I'd like to have: - a javascript file that contains the functions prepdraggables() and prepdroppables() - a way to call either function from application.html.erb or from a js.erb file I've tried using :content_for to store and reuse the code, but can't seem to get it working correctly. What I currently have in the head section of application.html.erb <% content_for :drag_drop_prep do %> <script type="text/javascript" charset="utf-8"> $(document).ready(function () { // declare all DOM elements with class draggable to be draggable $( ".draggable" ).draggable( { revert : 'invalid' }); // declare all DOM elements with class legal to be droppable $(".legal").droppable({ hoverClass : 'legal_hover', drop : function(event, ui) { var c = new Object(); c['die'] = ui.draggable.attr("id"); c['cell'] = $(this).attr("id"); c['authenticity_token'] = encodeURIComponent(window._token); $.ajax({ type: "POST", url: "/placeDie", data: c, timeout: 5000 }); }}); }); </script> <% end %> undo.js.erb $("#board").html("<%= escape_javascript(render :partial => 'shared/board', :locals => { :playable => true, :restartable => !session[:challenge]}) %>") // This is where I want to prepare draggables. <%= javascript_include_tag "customdragdrop.js" %> // assuming this file had the draggables code from above in a prepdraggables() function prepdraggables();

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• Why do we have reinterpret_cast in C++ when two chained static_cast can do it's job?

  - by Nawaz

  Say I want to cast A* to char* and vice-versa, we have two choices (I mean, many of us think we've two choices, because both seems to work! Hence the confusion!): struct A { int age; char name[128]; }; A a; char *buffer = static_cast<char*>(static_cast<void*>(&a)); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 Both work fine. //convert back A *pA = static_cast<A*>(static_cast<void*>(buffer)); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Even this works fine! So why do we have reinterpret_cast in C++ when two chained static_cast can do it's job? Some of you might think this topic is a duplicate of the previous topics such as listed at the bottom of this post, but it's not. Those topics discuss only theoretically, but none of them gives even a single example demonstrating why reintepret_cast is really needed, and two static_cast would surely fail. I agree, one static_cast would fail. But how about two? If the syntax of two chained static_cast looks cumbersome, then we can write a function template to make it more programmer-friendly: template<class To, class From> To any_cast(From v) { return static_cast<To>(static_cast<void*>(v)); } And then we can use this, as: char *buffer = any_cast<char*>(&a); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 //convert back A *pA = any_cast<A*>(buffer); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Also, see this situation where any_cast can be useful: Proper casting for fstream read and write member functions. So my question basically is, Why do we have reinterpret_cast in C++? Please show me even a single example where two chained static_cast would surely fail to do the same job? Which cast to use; static_cast or reinterpret_cast? Cast from Void* to TYPE* : static_cast or reinterpret_cast

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• First record does not show in pagination script

  - by whitstone86

  This is my pagination script which extracts info for my TV guide project that I am working on. Currently I've been experimenting with different PHP/MySQL before it becomes a production site. This is my current script: <?php /*********************************** * PhpMyCoder Paginator * * Created By PhpMyCoder * * 2010 PhpMyCoder * * ------------------------------- * * You may use this code as long * * as this notice stays intact and * * the proper credit is given to * * the author. * ***********************************/ // set the default timezone to use. Available since PHP 5.1 putenv("TZ=US/Eastern") ?> <head> <title> Pagination Test - Created By PhpMyCoder</title> <style type="text/css"> #nav { font: normal 13px/14px Arial, Helvetica, sans-serif; margin: 2px 0; } #nav a { background: #EEE; border: 1px solid #DDD; color: #000080; padding: 1px 7px; text-decoration: none; } #nav strong { background: #000080; border: 1px solid #DDD; color: #FFF; font-weight: normal; padding: 1px 7px; } #nav span { background: #FFF; border: 1px solid #DDD; color: #999; padding: 1px 7px; } </style> </head> <?php //Require the file that contains the required classes include("pmcPagination.php"); //PhpMyCoder Paginator $paginator = new pmcPagination(20, "page"); //Connect to the database mysql_connect("localhost","root","PASSWORD"); //Select DB mysql_select_db("mytvguide"); //Select only results for today and future $result = mysql_query("SELECT programme, channel, airdate, expiration, episode, setreminder FROM lagunabeach where expiration >= now() order by airdate, 3 ASC LIMIT 0, 100;"); //You can also add reuslts to paginate here mysql_data_seek($queryresult,0) ; while($row = mysql_fetch_array($result)) { $paginator->add(new paginationData($row['programme'], $row['channel'], $row['airdate'], $row['expiration'], $row['episode'], $row['setreminder'])); } ?> <?php //Show the paginated results $paginator->paginate (); ?><? include("pca-footer1.php"); ?> <?php //Show the navigation $paginator->navigation(); ?> Despite me having two records for the programmes airing today, it only shows records from the second one onwards - the programme that airs at 8:35pm UK time GMT does not show, but the later 11:25pm UK time GMT one does show. How should I fix this? Above is my code if that is of any use! Thanks

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• Is it possible to use CSS to align these divs/spans in a table-like manner?

  - by Justin L.

  I have <div class='line'> <div class='chord_line'> <span class='chord_block'></span> <span class='chord_block'>E</span> <span class='chord_block'>B</span> <span class='chord_block'>C#m</span> <span class='chord_block'>A</span> </div> <div class='lyric_line'> <span class='lyric_block'></span> <span class='lyric_block'>Just a</span> <span class='lyric_block'>small-town girl</span> <span class='lyric_block'>living in a</span> <span class='lyric_block'>lonely world</span> </div> </div> (Excuse me for not being too familiar with proper css conventions for when to use div/spans) I want to be able to display them so that each chord_block span and lyric_block span is aligned vertically, as if they were left-aligned and on the same row of a table. For example: E B C#m A Just a small-town girl living in a lonely world (There will often be cases where an empty chord block is matched up to non-empty lyric block, and vice-versa.) I'm completely new to using CSS to align things, and have had no real understanding/experience of CSS aside from changing background colors and link styles. Is this possible in CSS? If not, how could the div/class nesting structure be revised to make this possible? I could change the spans to divs if necessary. Some things I cannot use: I can't change the structure to group things by a chord_and_lyric_block div (and have their width stretch to the length of the lyric, and stack them horizontally), because I couldn't really copy/select the lyrical lines continuously in their entirety, which is extremely critical. I'm trying to avoid a table-like solution, because this data is not tabular at all. The chord line and the lyric line are meant to be read as one continuous line, not a set of cells. Also, apart from the design philosophy reasons, I think it might have the same problems as the previous thing bullet point. If this is possible, what div/span attributes should I be using? Can you provide sample css? If this is not possible, can it be done with javascript?

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• C++: get const or non-const reference type from trait

  - by maciekp

  I am writing a functor F which takes function of type void (*func)(T) and func's argument arg. Then functor F calls func with arg. I would like F not to copy arg, just to pass it as reference. But then I cannot simply write "void F(void (*func)(T), T&)" because T could be a reference. So I am trying to write a trait, which allows to get proper reference type of T: T -> T& T& -> T& const T -> const T& const T& -> const T& I come up with something like this: template<typename T> struct type_op { typedef T& valid_ref_type; }; template<typename T> struct type_op<T&> { typedef typename type_op<T>::valid_ref_type valid_ref_type; }; template<typename T> struct type_op<const T> { typedef const T& valid_ref_type; }; template<typename T> struct type_op<const T&> { typedef const T& valid_ref_type; }; Which doesn't work for example for void a(int x) { std::cout << x << std::endl; } F(&a, 7); Giving error: invalid initialization of non-const reference of type ‘int&’ from a temporary of type ‘int’ in passing argument 2 of ‘void f(void (*)(T), typename type_op::valid_ref_type) [with T = int]’ How to get this trait to work?

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• Using hidden values with jQuery (and ASP.NET MVC) -- not working?

  - by SlackerCoder

  Im using a couple of JSON calls to render data, etc etc. In order to keep the proper key value, I am storing it in a tag. I have this in several places in my code, none of which cause an issue like this one is. Here is the jQuery: The call that "sets" the value: $("a[id^='planSetupAddNewPlan']").live('click', function() { var x = $(this).attr('id'); x = x.substring(19); $("#hidPlanSetupCurrentGroupKey").val(x); $.getJSON("/GroupSetup/PlanSetupAddNewList", { GroupKey: x }, function(data) { $("#planSetupAddNew").html('' + data.TableResult + ''); alert('First Inside 2 ' + x); $.blockUI({ message: $("#planSetupAddNew") }); }); }); The call that "gets" the value: $("#ddlPlanSetupAddNewProduct").live('change', function() { var a = $("#hidPlanSetupCurrentGroupKey").val(); var prod = $(this).val(); alert(a); $.getJSON("/GroupSetup/PlanSetupChangePlanList", { GroupKey: a, Product: prod }, function(data) { if (data.Message == "Success") { $("#planSetupAddNewPlan").html('' + data.TableResult + ''); } else if (data.Message == "Error") { //Do something } }); }); Here is the html in question: <div id="planSetupAddNew" style="display:none; cursor: default;"> <input type="hidden" id="hidPlanSetupCurrentGroupKey" /> <div id="planSetupAddNewData"> </div> </div> In the first section, the alert ('First Inside 2 ' + x) returns what I expect (where x = the key value), and if I add a line to display the contents of the hidden field, that works as well: ie. var key = $("#hidPlanSetupCurrentGroupKey").val(); alert(key); In the "alert(a);" call, I am getting "undefined". I have looked at the other code in the same view and it is the same and it works. I must be missing something, or have some sort of mistype that I havent caught. Just an overview of the controller events: The first call (/GroupSetup/PlanSetupAddNewList) will return an html string building a "form" for users to enter information into. The second call (/GroupSetup/PlanSetupChangePlanList) just changes a second dropdown based on the first dropdown selection (overwriting the html in the div). If you need more info, let me know! Any thoughts/tips/pointers/suggestions?!?! Thanks for all your help :)

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• How to approach copying objects with smart pointers as class attributes?

  - by tomislav-maric

  From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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• Dynamic allocating of const member structures

  - by Willy

  I've got class which is using plain-only-data struct with const variables and I'm not sure, if I'm allocating these structures in a proper way. It looks more or less like: #include <cstdlib> #include <iostream> using std::cout; using std::endl; struct some_const_struct { const int arg1; const int arg2; }; class which_is_using_above_struct { public: some_const_struct* m_member; const some_const_struct* const m_const_member; public: const some_const_struct& get_member() const { return *m_member; } const some_const_struct& get_const_member() const { return *m_const_member; } void set_member(const int a, const int b) { if(m_member != NULL) { delete m_member; m_member = NULL; } m_member = new some_const_struct((some_const_struct){a, b}); } explicit which_is_using_above_struct(const int a, const int b) : m_const_member(new some_const_struct((const some_const_struct){a, b})) { m_member = NULL; } ~which_is_using_above_struct() { if(m_member != NULL) { delete m_member; } if(m_const_member != NULL) { delete m_const_member; } } }; int main() { which_is_using_above_struct c(1, 2); c.set_member(3, 4); cout << "m_member.arg1 = " << c.get_member().arg1 << endl; cout << "m_member.arg2 = " << c.get_member().arg2 << endl; cout << "m_const_member.arg1 = " << c.get_const_member().arg1 << endl; cout << "m_const_member.arg2 = " << c.get_const_member().arg2 << endl; return 0; } I'm just not quite sure if the statement: m_member = new some_const_struct((some_const_struct){a, b}); doesn't produce unnessesary use of some_const_struct's copy constructor, ergo allocating that struct twice. What do you think? And is it reasonable to make that struct's members const? (they're not supposed to change in their lifetime at all)

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• Inbreeding-immune database structure

  - by Nick Savage

  I have an application that requires a "simple" family tree. I would like to be able to perform queries that will give me data for an entire family given one id from a member in the family. I say simple because it does not need to take into account adoption or any other obscurities. The requirements for the application are as follows: Any two people will not be able to breed if they're from the same genetic line Needs to allow for the addition of new family lines (new people with no previous family) Need to be able to pull siblings, parents separately through queries I'm having trouble coming up with the proper structure for the database. So far I've come up with two solutions but they're not very reliable and will probably get out of hand quite quickly. Solution 1 involves placing a family_ids field on the people table and storing a list of unique family ids. Each time two people breed the lists are checked against each other to make sure no ids match and if everything checks out will merge the two lists and set that as the child's family_ids field. Example: Father (family_ids: (null)) breeds with Mother (family_ids: (213, 519)) -> Child (family_ids: (213, 519)) breeds with Random Person (family_ids: (813, 712, 122, 767)) -> Grandchild (family_ids: (213, 519, 813, 712, 122, 767)) And so on and so forth... The problem I see with this is the lists becoming unreasonably large as time goes on. Solution 2 uses cakephp's associations to declare: public $belongsTo = array( 'Father' => array( 'className' => 'User', 'foreignKey' => 'father_id' ), 'Mother' => array( 'className' => 'User', 'foreignKey' => 'mother_id' ) ); Now setting recursive to 2 will fetch the results of the mother and father, along with their mother and father, and so on and so forth all the way down the line. The problem with this route is that the data is in nested arrays and I'm unsure of how to efficiently work through the code. If anyone would be able to steer me in the direction of the most efficient way to handle what I want to achieve that would be tremendously helpful. Any and all help is greatly appreciated and I'll gladly answer any questions anyone has. Thanks a lot.

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• Controlling the USB from Windows

  - by b-gen-jack-o-neill

  Hi, I know this probably is not the easiest thing to do, but I am trying to connect Microcontroller and PC using USB. I dont want to use internal USART of Microcontroller or USB to RS232 converted, its project indended to help me understand various principles. So, getting the communication done from the Microcontroller side is piece of cake - I mean, when I know he protocol, its relativelly easy to implement it on Micro, becouse I am in direct control of evrything, even precise timing. But this is not the case of PC. I am not very familiar with concept of Windows handling the devices connected. In one of my previous question I ask about how Windows works with devices thru drivers. I understood that for internal use of Windows, drivers must have some default set of functions available to OS. I mean, when OS wants to access HDD, it calls HDD driver (which is probably internal in OS), with specific "questions" so that means that HDD driver has to be written to cooperate with Windows, to have write function in the proper place to be called by the OS. Something similiar is for GPU, Even DirectX, I mean DirectX must call specific functions from drivers, so drivers must be written to work with DX. I know, many functions from WinAPI works on their own, but even "simple" window must be in the end written into framebuffer, using MMIO to adress specified by drivers. Am I right? So, I expected that Windows have internal functions, parts of WinAPI designed to work with certain comonly used things. To call manufacturer-designed drivers. But this seems to not be entirely true becouse Windows has no way to communicate thru Paralel port. I mean, there is no function in the WinAPI to work with serial port, but there are funcions to work with HDD,GPU and so. But now there comes the part I am getting very lost at. So, I think Windows must have some built-in functions to communicate thru USB, becouse for example it handles USB flash memory. So, is there any WinAPI function designed to let user to operate USB thru that function, or when I want to use USB myself, do I have to call desired USB-driver function myself? Becouse all you need to send to USB controller is device adress and the infromation right? I mean, I don´t have to write any new drivers, am I right? Just to call WinAPI function if there is such, or directly call original USB driver. Does any of this make some sense?

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• how to invoke an activity of a library project from an android apps

  - by Austin

  I have an open source android code that I need to use in my android apps. It has all the source code as well as resource files, manifest files and class path. It can be compiled as a separate android apps. I have constraints for using the open source. 1. I can't change a single line of code. 2. I can't use it as a separate apps. These constraints are non negotiable. What I have done is I have compiled the open source as class library(in Eclipse: Project Properties-Android- Tick check box Is Library). This has resulted in generation of .class files(in bin) for the java files and resource files. This open source has an android activity that i want to open from my application. So I have linked the directory of these sets of class files in the source section of my java build path( in .classpath). I have declared the activity in my manifest file with proper action intent filters. Now when I am trying to call activity from my code, its not working. Cleaning and rebuilding doesn't help. However, if I build the open source project and my apps in the same workspace of eclipse and link the open source in my apps in exact same manner it works fine. I am not able to identify the difference. All settings seems to be same(all files are identical in both the cases). But only in the second case it works. I have tried it as jar file also. I have build the open source as project library and exported it into a jar file(excluding manifest file). But in that case I am getting the following error UNEXPECTED TOP-LEVEL EXCEPTION: java.lang.IllegalArgumentException: already added: .... Conversion to Dalvik format failed with error 1 This I guess is coming because the android library(2.2) has been included twice in my apps( one for building my apps & another for building the open source). I dont know how to avoid this. Cleaning the project doesn't help. What i require is to use the open source and invoking it's activities in my apps without violating the constraints. If i can use the open source as bunch of .class files then great, or else any other way will do fine. Please look into it and let me know. Thanks

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• Should I HttpCombine Google Jquery Hosted File?

  - by chobo2

  Hi I am using something called HttpCombiner: http://code.msdn.microsoft.com/HttpCombiner An HTTP handler that combines multiple CSS, Javascript or URL into one response for faster page load. It can combine, compress and cache response which results in faster page load and better scalability of web application It's a good practice to use many small Javascript and CSS files instead of one large Javascript/CSS file for better code maintainability, but bad in terms of website performance. Although you should write your Javascript code in small files and break large CSS files into small chunks but when browser requests those javascript and css files, it makes one Http request per file. Every Http Request results in a network roundtrip form your browser to the server and the delay in reaching the server and coming back to the browser is called latency. So, if you have four javascripts and three css files loaded by a page, you are wasting time in seven network roundtrips. Within USA, latency is average 70ms. So, you waste 7x70 = 490ms, about half a second of delay. Outside USA, average latency is around 200ms. So, that means 1400ms of waiting. Browser cannot show the page properly until Css and Javascripts are fully loaded. So, the more latency you have, the slower page loads. You can reduce the wait time by using a CDN. Read my previous blog post about using CDN. However, a better solution is to deliver multiple files over one request using an HttpHandler that combines several files and delivers as one output. So, instead of putting many or tag, you just put one and one tag, and point them to the HttpHandler. You tell the handler which files to combine and it delivers those files in one response. This saves browser from making many requests and eliminates the latency. This Http Handler reads the file names defined in a configuration and combines all those files and delivers as one response. It delivers the response as gzip compressed to save bandwidth. Moreover, it generates proper cache header to cache the response in browser cache, so that, browser does not request it again on future visit. Now I am wondering since it can handle adding links should I put in it the jquery file? The reason I am not sure is if it gets combined with my other files I think I might close the advantages of it being hosted on googles servers such as caching(my thinking is if it gets combined it will look different so even if a user has it in it's cache I am not sure if it will use the one for the cahce or not). So should I combine it or only the finals that I am using locally?

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• Complex multiple join query across 3 tables

  - by Keir Simmons

  I have 3 tables: shops, PRIMARY KEY cid,zbid shop_items, PRIMARY KEY id shop_inventory, PRIMARY KEY id shops a is related to shop_items b by the following: a.cid=b.cid AND a.zbid=b.szbid shops is not directly related to shop_inventory shop_items b is related to shop_inventory c by the following: b.cid=c.cid AND b.id=c.iid Now, I would like to run a query which returns a.* (all columns from shops). That would be: SELECT a.* FROM shops a WHERE a.cid=1 AND a.zbid!=0 Note that the WHERE clause is necessary. Next, I want to return the number of items in each shop: SELECT a.*, COUNT(b.id) items FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid As you can see, I have added a GROUP BY clause for this to work. Next, I want to return the average price of each item in the shop. This isn't too hard: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid My next criteria is where it gets complicated. I also want to return the unique buyers for each shop. This can be done by querying shop_inventory c, getting the COUNT(DISTINCT c.zbid). Now remember how these tables are related; this should only be done for the rows in c which relate to an item in b which is owned by the respective shop, a. I tried doing the following: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price, COUNT(DISTINCT c.zbid) FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid LEFT JOIN shop_inventory c ON c.cid=b.cid AND c.iid=b.id WHERE a.cid=1 GROUP BY b.szbid,b.cid However, this did not work as it messed up the items value. What is the proper way to achieve this result? I also want to be able to return the total number of purchases made in each shop. This would be done by looking at shop_inventory c and adding up the c.quantity value for each shop. How would I add that in as well?

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• Calling compiled C from R with .C()

  - by Sarah

  I'm trying to call a program (function getNBDensities in the C executable measurementDensities_out) from R. The function is passed several arrays and the variable double runsum. Right now, the getNBDensities function basically does nothing: it prints to screen the values of passed parameters. My problem is the syntax of calling the function: array(.C("getNBDensities", hr = as.double(hosp.rate), # a vector (s x 1) sp = as.double(samplingProbabilities), # another vector (s x 1) odh = as.double(odh), # another vector (s x 1) simCases = as.integer(x[c("xC1","xC2","xC3")]), # another vector (s x 1) obsCases = as.integer(y[c("yC1","yC2","yC3")]), # another vector (s x 1) runsum = as.double(runsum), # double DUP = TRUE, NAOK = TRUE, PACKAGE = "measurementDensities_out")$f, dim = length(y[c("yC1","yC2","yC3")]), dimnames = c("yC1","yC2","yC3")) The error I get, after proper execution of the function (i.e., the right output is printed to screen), is Error in dim(data) <- dim : attempt to set an attribute on NULL I'm unclear what the dimensions are that I should be passing the function: should it be s x 5 + 1 (five vectors of length s and one double)? I've tried all sorts of combinations (including sx5+1) and have found only seemingly conflicting descriptions/examples online of what's supposed to happen here. For those who are interested, the C code is below: #include <R.h> #include <Rmath.h> #include <math.h> #include <Rdefines.h> #include <R_ext/PrtUtil.h> #define NUM_STRAINS 3 #define DEBUG void getNBDensities( double *hr, double *sp, double *odh, int *simCases, int *obsCases, double *runsum ); void getNBDensities( double *hr, double *sp, double *odh, int *simCases, int *obsCases, double *runsum ) { #ifdef DEBUG for ( int s = 0; s < NUM_STRAINS; s++ ) { Rprintf("\nFor strain %d",s); Rprintf("\n\tHospitalization rate = %lg", hr[s]); Rprintf("\n\tSimulation probability = %lg",sp[s]); Rprintf("\n\tSimulated cases = %d",simCases[s]); Rprintf("\n\tObserved cases = %d",obsCases[s]); Rprintf("\n\tOverdispersion parameter = %lg",odh[s]); } Rprintf("\nRunning sum = %lg",runsum[0]); #endif } naive solution While better (i.e., potentially faster or syntactically clearer) solutions may exist (see Dirk's answer below), the following simplification of the code works: out<-.C("getNBDensities", hr = as.double(hosp.rate), sp = as.double(samplingProbabilities), odh = as.double(odh), simCases = as.integer(x[c("xC1","xC2","xC3")]), obsCases = as.integer(y[c("yC1","yC2","yC3")]), runsum = as.double(runsum)) The variables can be accessed in >out.

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• Can you call FB.login inside a callback from other FB methods (like FB.getLoginStatus) without triggering popup blockers?

  - by Erik Kallevig

  I'm trying to set up a pretty basic authentication logic flow with the FB JavaScript SDK to check a user's logged-in status and permissions before performing an action (and prompting the user to login with permissions if they are not)... User types a message into a textarea on my site to post to their Facebook feed and click's a 'post to facebook' button on my site. In response to the click, I check user's logged in status with FB.getLoginStatus In the callback to FB.getLoginStatus, if user is not logged in, prompt them to login (FB.login). In the callback to FB.login I then need to make sure they have the right permissions so I make a call to FB.api('/me/permissions') -- if they don't , I again prompt them to login (FB.login) The problem I'm running into is that anytime I try to call FB.login inside a callback to other FB methods, the browser seems to lose track of the origin of execution (the click) and thus will block the popup. I'm wondering if I'm missing some way to prompt the user to login after checking their status without the browser mistakenly thinking that it's not a user-initiated popup? I've currently fallen back to just calling FB.login() first regardless. The undesired side effect of this approach, however, is that if the user is already logged-in with permissions and I'm still calling FB.login, the auth popup will open and close immediately before continuing, which looks rather buggy despite being functional. It seems like checking a user's login status and permissions before doing something would be a common flow so I feel like I'm missing something. Here's some example code. <div onclick="onClickPostBtn()">Post to Facebook</div> <script> // Callback to click on Post button. function onClickPostBtn() { // Check if logged in, prompt to do so if not. FB.getLoginStatus(function(response) { if (response.status === 'connected') { checkPermissions(response.authResponse.accessToken); } else { FB.login(function(){}, {scope: 'publish_stream'}) } }); } // Logged in, check permissions. function checkPermissions(accessToken) { FB.api('/me/permissions', {'access_token': accessToken}, function(response){ // Logged in and authorized for this site. if (response.data && response.data.length) { // Parse response object to check for permission here... if (hasPermission) { // Logged in with permission, perform some action. } else { // Logged in without proper permission, request login with permissions. FB.login(function(){}, {scope: 'publish_stream'}) } // Logged in to FB but not authorized for this site. } else { FB.login(function(){}, {scope: 'publish_stream'}) } } ); } </script>

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• Is it possible to use CSS to align these divs/spans in a table-like manner? (While still retaining continuity)

  - by Justin L.

  I have <div class='line'> <div class='chord_line'> <span class='chord_block'></span> <span class='chord_block'>E</span> <span class='chord_block'>B</span> <span class='chord_block'>C#m</span> <span class='chord_block'>A</span> </div> <div class='lyric_line'> <span class='lyric_block'></span> <span class='lyric_block'>Just a</span> <span class='lyric_block'>small-town girl</span> <span class='lyric_block'>living in a</span> <span class='lyric_block'>lonely world</span> </div> </div> (Excuse me for not being too familiar with proper css conventions for when to use div/spans) I want to be able to display them so that each chord_block span and lyric_block span is aligned vertically, as if they were left-aligned and on the same row of a table. For example: E B C#m A Just a small-town girl living in a lonely world (There will often be cases where an empty chord block is matched up to non-empty lyric block, and vice-versa.) I'm completely new to using CSS to align things, and have had no real understanding/experience of CSS aside from changing background colors and link styles. Is this possible in CSS? If not, how could the div/class nesting structure be revised to make this possible? I could change the spans to divs if necessary. Some things I cannot use: I can't change the structure to group things by a chord_and_lyric_block div (and have their width stretch to the length of the lyric, and stack them horizontally), because I couldn't really copy/select the lyrical lines continuously in their entirety, which is extremely critical. I'm trying to avoid a table-like solution, because this data is not tabular at all. The chord line and the lyric line are meant to be read as one continuous line, not a set of cells. Also, apart from the design philosophy reasons, I think it might have the same problems as the previous thing bullet point. If this is possible, what div/span attributes should I be using? Can you provide sample css? If this is not possible, can it be done with javascript? EDIT: I'm sorry I wasn't clear at the start, but I would like a solution that allows both the chord line and the lyric line to be "selectable" and continuous.

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• Authlogic: passwords saved in the DB are not working as expected.

  - by user570459

  Hello everyone, Im having trouble with authlogic on my production server. Im able to update passwords in the database but when i try to validate a user using the new password, the validation fails. Please check the below console output. Notice how the salt and crypted_password fields get update before and after the new password is saved. The issue is only on my production server (running passenger). Everything works fine on my development machine. => #<User id: 3, login: "saravk", email: "[email protected]", crypted_password: "9bc86247105e940bb748ab680c0e77d9c44a82ea", salt: "WdVpQIdwl68k8lJWOU"> irb(main):003:0> u.password = "kettik123" => "kettik123" irb(main):004:0> u.password_confirmation = "kettik123" => "kettik123" irb(main):005:0> u.save! => true irb(main):006:0> u.valid_password?("kettik123") => true irb(main):007:0> u.reload => #<User id: 3, login: "saravk", email: "[email protected]", crypted_password: "f059007c56f498a12c63209c849c1e65bb151174", salt: "lVmmczhyGE0gxsbV421A"> irb(main):008:0> u.valid_password?("kettik123") => false The authlogic configuration in my User model.. class User < ActiveRecord::Base acts_as_authentic do |c| c.login_field :email c.validate_login_field false c.validate_email_field false c.perishable_token_valid_for = 1.day c.disable_perishable_token_maintenance = true end I use the email field as the main key for the user. Also the email field is allowed to be blank in some cases (eg a facebook user) Also i belive that my schema is proper (in terms of the length of the salt & crypted password fields) create_table "users", :force => true do |t| t.string "login" t.string "email" t.string "crypted_password", :limit => 128, :default => "" t.string "salt", Any help on this would be highly appreciated. Thanks.

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• Adding Related Entities without using navigation properties

  - by Barisa Puter

  I have the following classes, set for testing: public class Company { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int Id { get; set; } public string Name { get; set; } } public class Employee { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int Id { get; set; } public string Name { get; set; } public int CompanyId { get; set; } public virtual Company Company { get; set; } } public class EFTestDbContext : DbContext { public DbSet<Employee> Employees { get; set; } public DbSet<Company> Companies { get; set; } } For the sake of testing, I wanted to insert one company and one employee for that company with single SaveChanges call, like this: Company company = new Company { Name = "Sample company" }; context.Companies.Add(company); // ** UNCOMMENTED FOR TEST 2 //Company company2 = new Company //{ // Name = "Some other company" //}; //context.Companies.Add(company2); Employee employee = new Employee { Name = "Hans", CompanyId = company.Id }; context.Employees.Add(employee); context.SaveChanges(); Even though I am not using navigational properties, but instead I've made relation over Id, this somehow mysteriously worked - employee was saved with proper foreign key to company which got updated from 0 to real value, which made me go ?!?! Some hidden C# feature? Then I've decided to add more code, which is commented in the snippet above, making it to be inserting of 2 x Company entity and 1 x Employee entity, and then I got exception: Unable to determine the principal end of the 'CodeLab.EFTest.Employee_Company' relationship. Multiple added entities may have the same primary key. Does this mean that in cases where foreign key is 0, and there is a single matching entity being inserted in same SaveChanges transaction, Entity Framework will assume that foreign key should be for that matching entity? In second test, when there are two entities matching the relation type, Entity Framework throws an exception as it is not able to figure out to which of the Companies Employee should be related to.

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