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• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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• I added a validation to one of my models, now Rails is telling me to add validation to the partial. Help!

  - by marcamillion

  This is the error I am getting: ArgumentError in Home#index Showing /app/views/clients/_form.html.erb where line #6 raised: You need to supply at least one validation Extracted source (around line #6): 3: render :partial => "clients/form", 4: :locals => {:client => client} 5: -%> 6: <% client ||= Client.new 7: new_client = client.new_record? %> 8: <%= form_for(client, :html => { :class=>"ajax-form", :id => "client-ajax-form"}, :remote => true, :disable_with => (new_client ? "Adding..." : "Saving...")) do |f| %> 9: <div class="validation-error" style="display:none"></div> My client model looks like this: class Client < ActiveRecord::Base # the user model for the client belongs_to :user has_many :projects, :order => 'created_at DESC', :dependent => :destroy #The following produces the designers for a particular client. #Get them from the relations where the current user is a client. has_one :ownership, :dependent => :destroy has_one :designer, :through => :ownership validates :name, :presence => true, :length => {:minimum => 1, :maximum => 128} validates :number_of_clients def number_of_clients Authorization.current_user.clients.count <= Authorization.current_user.plan.num_of_clients end end This is how the app/views/client/_form.html.erb partial looks: <%# Edit a single client render :partial => "clients/form", :locals => {:client => client} -%> <% client ||= Client.new new_client = client.new_record? %> <%= form_for(client, :html => { :class=>"ajax-form", :id => "client-ajax-form"}, :remote => true, :disable_with => (new_client ? "Adding..." : "Saving...")) do |f| %> <div class="validation-error" style="display:none"></div> <div> <label for="client_name"><span class="icon name-icon"> </span></label> <input type="text" class="name" size="20" name="client[name]" id="client_name" value="<%= client.name %>" > <%= f.submit(new_client ? "Add" : "Save", :class=> "green awesome")%> </div> <% end %> <% content_for(:deferred_js) do %> // From the Client Form $('#client-ajax-form') .bind("ajax:success", function(evt, data, status, xhr){ console.log("Calling Step View"); compv.updateStepView('client', xhr); }); <% end %> How do I fix that error ?

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• Recommended integration mechanism for bi-directional, authenticated, encrypted connection in C clien

  - by rcampbell

  Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see the latest evaluated result of z/4. The tricky part is that either the client or the server may change the variable value at any time, informing the other party immediately. More specifically, Client #3 - a C app - can initially tell the server that z = 20. An hour later that same client informs the server that z = 23. Likewise the server can later inform the client that z = 28. As caf pointed out in the comments, there can be a race condition when values are changed by the client and server simultaneously. The solution would be for both client and server to send the operation performed in their message, which would need to be executed by the other party. To keep things simple, let's limit the operations to (commutative) addition, allowing us to disregard message ordering. For example, the client seeds the server with z = 20: server:z=20, client:z=20 server sends {+3} message (so z=23 locally) & client sends {-2} message (so z=18 locally) at the exact same time server receives {-2} message at some point, adds to his local copy so z=21 client receives {+3} message at some point, adds to his local copy so z=21 As long as all messages are eventually evaluated by both parties, the correct answer will eventually be given to the users of the client and server since we limited ourselves to commutative operations (addition of 3 and -2). This does mean that both client and server can be returning incorrect answers in the time it takes for messages to be exchanged and processed. While undesirable, I believe this is unavoidable. Some possible implementations of this idea include: Open an encrypted, always on TCP socket connection for communication Pros: no additional infrastructure needed, client and server know immediately if there is a problem (disconnect) with the other party, fairly straightforward (except the the encryption), native support from both JVM and C platforms Cons: pretty low-level so you end up writing a lot yourself (protocol, delivery verification, retry-on-failure logic), probably have a lot of firewall headaches during client app installation Asynchronous messaging (ex: ActiveMQ) Pros: transactional, both C & Java integration, free up the client and server apps from needing retry logic or delivery verification, pretty straightforward encryption, easy extensibility via message filters/routers/etc Cons: need additional infrastructure (message server) which must never fail, Database or file system as asynchronous integration point Same pros/cons as above but messier RESTful Web Service Pros: simple, possible reuse of the server's existing REST API, SSL figures out the encryption problem for you (maybe use RSA key a la GitHub for authentication?) Cons: Client now needs to run a C HTTP REST server w/SSL, client and server need retry logic. Axis2 has both a Java and C version, but you may be limited to SOAP. What other techniques should I be evaluating? What real world experiences have you had with these mechanisms? Which do you recommend for this problem and why?

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• ASP.NET MVC 3 embrace dynamic type - CSDN.NET - CSDN Software Development Channel

  - by user559071

  About a decade ago, Microsoft will all bet on the WebForms and static types. With the complete package from scattered to the continuous development, and now almost every page can be viewed as its own procedure. Subsequent years, the industry continued to move in another direction, love is better than separation package, better than the late binding early binding to the idea. This leads to two very interesting questions. The first is the problem of terminology. Consider the original Smalltalk MVC model, view and controller is not only tightly coupled together, and usually in pairs. Most of the framework is that Microsoft, including the classic VB, WinForms, WebForms, WPF and Silverlight, they both use the code behind file to store the controller logic. But said "MVC" usually refers to the view and controller are loosely coupled framework. This is especially true for the Web framework, HTML form submission mechanism allows any views submitted to any of the controller. Since this article was mainly talking about Web technologies, so we need to use the modern definition. The second question is "If you're Microsoft, how to change orbit without causing too much pressure to the developer?" So far, the answer is: new releases each year, until the developers meet up. ASP.NET MVC's first product was released last March. Released in March this year, ASP.NET MVC 2.0. 3.0 RC 2 is currently in phase, expected to be released next March. December 10, Microsoft released ASP.NET MVC 3.0 Release Candidate 2. RC 2 is built on top of Microsoft's commitment to the jQuery: The default project template into jQuery 1.4.4, jQuery Validation 1.7 and jQuery UI. Although people think that Microsoft will focus shifted away from server-side controls to be a joke, but the introduction of Microsoft's jQuery UI is that this is the real thing. For those worried about the scalability of the developers, there are many excellent control can replace the session state. With SessionState property, you can tell the controller session state is read-only, read-write, or can be completely ignored in the. This site is no single server, but if a server needs to access another server session state, then this approach can provide a great help. MVC 3 contains Razor view engine. By default, the engine will be encoded HTML output, so that we can easily output on the screen the text of the original. HTML injection attacks even without the risk of encoded text can not easily prevent the page rendering. For many C # developers in the end do what is most shocking that MVC 3 for the controller and view and embrace the dynamic type. ViewBag property will open a dynamic object, developers can run on top of the object to add attributes. In general, it is used to send the view from the controller non-mode data. Scott Guthrie provides state of the sample contains text (such as the current time) and used to assemble the list box entries. Asked Link: http://www.infoq.com/cn/news/2010/12/ASPNET-MVC-3-RC-2; jsessionid = 3561C3B7957F1FB97848950809AD9483

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• Passing a list of files to javac

  - by Robert Menteer

  How can I get the javac task to use an existing fileset? In my build.xml I have created several filesets to be used in multiple places throughout build file. Here is how they have been defined: <fileset dir = "${src}" id = "java.source.all"> <include name = "**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.examples"> <include name = "**/Examples/**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.tests"> <include name = "**/Tests/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.project"> <include name = "**/*.java" /> <exclude name = "**/Examples/**/*.java" /> <exclude name = "**/Tests/**/*.java" /> </fileset> I have also used macrodef to compile the java files so the javac task does not need to be repeated multiple times. The macro looks like this: <macrodef name="compile"> <attribute name="sourceref"/> <sequential> <javac srcdir = "${src}" destdir = "${build}" classpathref = "classpath" includeantruntime = "no" debug = "${debug}"> <filelist dir="." files="@{sourceref}" /> <-- email is about this </javac> </sequential> What I'm trying to do is compile only the classes that are needed for specific targets not all the targets in the source tree. And do so without having to specify the files every time. Here are how the targets are defined: <target name = "compile-examples" depends = "init"> <compile sourceref = "${toString:java.source.examples}" /> </target> <target name = "compile-project" depends = "init"> <compile sourceref = "${toString:java.source.project}" /> </target> <target name = "compile-tests" depends = "init"> <compile sourceref = "${toString:java.source.tests}" /> </target> As you can see each target specifies the java files to be compiled as a simi-colon separated list of absolute file names. The only problem with this is that javac does not support filelist. It also does not support fileset, path or pathset. I've tried using but it treats the list as a single file name. Another thing I tried is sending the reference directly (not using toString) and using but include does not have a ref attribute. SO THE QUESTION IS: How do you get the javac task to use a reference to a fileset that was defined in another part of the build file? I'm not interested in solutions that cause me to have multiple javac tasks. Completely re-writting the macro is acceptable. Changes to the targets are also acceptable provided redundant code between targets is kept to a minimum. p.s. Another problem is that fileset wants a comma separated list. I've only done a brief search for a way to convert semi-colons to commas and haven't found a way to do that. p.p.s. Sorry for the yelling but some people are too quick to post responses that don't address the subject.

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• Bulk inserting and updating with Entity Framework (Probably a better alternative?)

  - by Dave

  I have a data set of devices, addresses, and companies that I need to import into our database, with the catch that our database may already include a specific device/address/company that is included in the new data set. If that is the case, I need to update that entry with the new information in the data set, excluding addresses. We check if an exact copy of that address exists, otherwise we make a new entry. My issue is that it is very slow to attempt to grab a device/company in EF and if it exist updated it, otherwise insert it. To fix this I tried to get all the companies, devices, and addresses and insert them into respective hashmaps, and check if the identifier of the new data exists in the hashmap. This hasn't led to any performance increases. I've included my code below. Typically I would do a batch insert, I'm not sure what I would do for a batch update though. Can someone advise a different route? var context = ObjectContextHelper.CurrentObjectContext; var oldDevices = context.Devices; var companies = context.Companies; var addresses = context.Addresses; Dictionary<string, Company> companyMap = new Dictionary<string, Company>(StringComparer.OrdinalIgnoreCase); Dictionary<string, Device> deviceMap = new Dictionary<string, Device>(StringComparer.OrdinalIgnoreCase); Dictionary<string, Address> addressMap = new Dictionary<string, Address>(StringComparer.OrdinalIgnoreCase); foreach (Company c in companies) { if (c.CompanyAccountID != null && !companyMap.ContainsKey(c.CompanyAccountID)) companyMap.Add(c.CompanyAccountID, c); } foreach (Device d in oldDevices) { if (d.SerialNumber != null && !deviceMap.ContainsKey(d.SerialNumber)) deviceMap.Add(d.SerialNumber, d); } foreach (Address a in addresses) { string identifier = GetAddressIdentifier(a); if (!addressMap.ContainsKey(identifier)) addressMap.Add(identifier, a); } foreach (DeviceData.TabsDevice device in devices) { // update a device Company tempCompany; Address tempAddress; Device currentDevice; if (deviceMap.ContainsKey(device.SerialNumber)) //update a device deviceMap.TryGetValue(device.SerialNumber, out currentDevice); else // insert a new device currentDevice = new Device(); currentDevice.SerialNumber = device.SerialNumber; currentDevice.SerialNumberTABS = device.SerialNumberTabs; currentDevice.Model = device.Model; if (device.CustomerAccountID != null && device.CustomerAccountID != "") { companyMap.TryGetValue(device.CustomerAccountID, out tempCompany); currentDevice.CustomerID = tempCompany.CompanyID; currentDevice.CustomerName = tempCompany.CompanyName; } if (companyMap.TryGetValue(device.ServicingDealerAccountID, out tempCompany)) currentDevice.CompanyID = tempCompany.CompanyID; currentDevice.StatusID = 1; currentDevice.Retries = 0; currentDevice.ControllerFamilyID = 1; if (currentDevice.EWBFrontPanelMsgOption == null) // set the Panel option to the default if it isn't set already currentDevice.EWBFrontPanelMsgOption = context.EWBFrontPanelMsgOptions.Where( i => i.OptionDescription.Contains("default")).Single(); // link the device to the existing address as long as it is actually an address if (addressMap.TryGetValue(GetAddressIdentifier(device.address), out tempAddress)) { if (GetAddressIdentifier(device.address) != "") currentDevice.Address = tempAddress; else currentDevice.Address = null; } else // insert a new Address and link the device to it (if not null) { if (GetAddressIdentifier(device.address) == "") currentDevice.Address = null; else { tempAddress = new Address(); tempAddress.Address1 = device.address.Address1; tempAddress.Address2 = device.address.Address2; tempAddress.Address3 = device.address.Address3; tempAddress.Address4 = device.address.Address4; tempAddress.City = device.address.City; tempAddress.Country = device.address.Country; tempAddress.PostalCode = device.address.PostalCode; tempAddress.State = device.address.State; addresses.AddObject(tempAddress); addressMap.Add(GetAddressIdentifier(tempAddress), tempAddress); currentDevice.Address = tempAddress; } } if (!deviceMap.ContainsKey(device.SerialNumber)) // if inserting, add to context { oldDevices.AddObject(currentDevice); deviceMap.Add(device.SerialNumber, currentDevice); } } context.SaveChanges();

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• Performance issues with jms and spring integration. What is wrong with the following configuration?

  - by user358448

  I have a jms producer, which generates many messages per second, which are sent to amq persistent queue and are consumed by single consumer, which needs to process them sequentially. But it seems that the producer is much faster than the consumer and i am having performance and memory problems. Messages are fetched very very slowly and the consuming seems to happen on intervals (the consumer "asks" for messages in polling fashion, which is strange?!) Basically everything happens with spring integration. Here is the configuration at the producer side. First stake messages come in stakesInMemoryChannel, from there, they are filtered throw the filteredStakesChannel and from there they are going into the jms queue (using executor so the sending will happen in separate thread) <bean id="stakesQueue" class="org.apache.activemq.command.ActiveMQQueue"> <constructor-arg name="name" value="${jms.stakes.queue.name}" /> </bean> <int:channel id="stakesInMemoryChannel" /> <int:channel id="filteredStakesChannel" > <int:dispatcher task-executor="taskExecutor"/> </int:channel> <bean id="stakeFilterService" class="cayetano.games.stake.StakeFilterService"/> <int:filter input-channel="stakesInMemoryChannel" output-channel="filteredStakesChannel" throw-exception-on-rejection="false" expression="true"/> <jms:outbound-channel-adapter channel="filteredStakesChannel" destination="stakesQueue" delivery-persistent="true" explicit-qos-enabled="true" /> <task:executor id="taskExecutor" pool-size="100" /> The other application is consuming the messages like this... The messages come in stakesInputChannel from the jms stakesQueue, after that they are routed to 2 separate channels, one persists the message and the other do some other stuff, lets call it "processing". <bean id="stakesQueue" class="org.apache.activemq.command.ActiveMQQueue"> <constructor-arg name="name" value="${jms.stakes.queue.name}" /> </bean> <jms:message-driven-channel-adapter channel="stakesInputChannel" destination="stakesQueue" acknowledge="auto" concurrent-consumers="1" max-concurrent-consumers="1" /> <int:publish-subscribe-channel id="stakesInputChannel" /> <int:channel id="persistStakesChannel" /> <int:channel id="processStakesChannel" /> <int:recipient-list-router id="customRouter" input-channel="stakesInputChannel" timeout="3000" ignore-send-failures="true" apply-sequence="true" > <int:recipient channel="persistStakesChannel"/> <int:recipient channel="processStakesChannel"/> </int:recipient-list-router> <bean id="prefetchPolicy" class="org.apache.activemq.ActiveMQPrefetchPolicy"> <property name="queuePrefetch" value="${jms.broker.prefetch.policy}" /> </bean> <bean id="connectionFactory" class="org.springframework.jms.connection.CachingConnectionFactory"> <property name="targetConnectionFactory"> <bean class="org.apache.activemq.ActiveMQConnectionFactory"> <property name="brokerURL" value="${jms.broker.url}" /> <property name="prefetchPolicy" ref="prefetchPolicy" /> <property name="optimizeAcknowledge" value="true" /> <property name="useAsyncSend" value="true" /> </bean> </property> <property name="sessionCacheSize" value="10"/> <property name="cacheProducers" value="false"/> </bean>

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• Accessing a vector<vector<int>> as a flat array

  - by user1762276

  For this array: vector<vector<int> > v; v.push_back(vector<int>(0)); v.back().push_back(1); v.back().push_back(2); v.back().push_back(3); v.back().push_back(4); I can output {1, 2, 3, 4} easily enough: cout << v[0][0] << endl; cout << v[0][1] << endl; cout << v[0][2] << endl; cout << v[0][3] << endl; To access it as a flat array I can do this: int* z = (int*)&v[0].front(); cout << z[0] << endl; cout << z[1] << endl; cout << z[2] << endl; cout << z[3] << endl; Now, how do I access the multidimensional vector as a flat multidimensional array? I cannot use the same format as accessing a single-dimensional vector: // This does not work (outputs garbage) int** n = (int**)&v.front(); cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; The workaround I've found is to do this: int** n = new int* [v.size()]; for (size_t i = 0; i < v.size(); i++) { n[i] = &v.at(i).front(); } cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; Is there a way to access the entire multidimensional vector like a flat c-style array without having to dynamically allocate each dimension above the data before accessing it? Speed is not critical in the implementation and clarity for maintenance is paramount. A multidimensional vector is just fine for storing the data. However, I want to also expose the data as a flat c-style array in the SDK so that it can be easily accessible by other languages. This means that exposing the vectors as an STL object is a no go. The solution I came up with works fine for my needs as I only evaluate the array once at the very end of processing to "flatten" it. However, is there a better way to go about this? Or am I already doing it the best way I possibly can without re-implementing my own data structure (overkill since my flatten code is only a few lines). Thank you for your advice, friends!

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• Algorithm to select groups of similar items in 2d array

  - by mafutrct

  There is a 2d array of items (in my case they are called Intersections). A certain item is given as a start. The task is to find all items directly or indirectly connected to this item that satisfy a certain function. So the basic algorithm is like this: Add the start to the result list. Repeat until no modification: Add each item in the array that satisfies the function and touches any item in the result list to the result list. My current implementation looks like this: private IList<Intersection> SelectGroup ( Intersection start, Func<Intersection, Intersection, bool> select) { List<Intersection> result = new List<Intersection> (); Queue<Intersection> source = new Queue<Intersection> (); source.Enqueue (start); while (source.Any ()) { var s = source.Dequeue (); result.Add (s); foreach (var neighbour in Neighbours (s)) { if (select (start, neighbour) && !result.Contains (neighbour) && !source.Contains (neighbour)) { source.Enqueue (neighbour); } } } Debug.Assert (result.Distinct ().Count () == result.Count ()); Debug.Assert (result.All (x => select (x, result.First ()))); return result; } private List<Intersection> Neighbours (IIntersection intersection) { int x = intersection.X; int y = intersection.Y; List<Intersection> list = new List<Intersection> (); if (x > 1) { list.Add (GetIntersection (x - 1, y)); } if (y > 1) { list.Add (GetIntersection (x, y - 1)); } if (x < Size) { list.Add (GetIntersection (x + 1, y)); } if (y < Size) { list.Add (GetIntersection (x, y + 1)); } return list; } (The select function takes a start item and returns true iff the second item satisfies.) This does its job and turned out to be reasonable fast for the usual array sizes (about 20*20). However, I'm interested in further improvements. Any ideas? Example (X satisfies in relation to other Xs, . does never satisfy): .... XX.. .XX. X... In this case, there are 2 groups: a central group of 4 items and a group of a single item in the lower left. Selecting the group (for instance by starting item [2, 2]) returns the former, while the latter can be selected using the starting item and sole return value [0, 3]. Example 2: .A.. ..BB A.AA This time there are 4 groups. The 3 A groups are not connected, so they are returned as separate groups. The bigger A and B groups are connected, but A does not related to B so they are returned as separate groups.

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• How do I compare two datatables

  - by cmrhema

  I have a datatable that will consist of 72 columns. I will download it in the excel sheet using VSTO, which works fine. Now the user will change either one of these rows or all of these rows and will also insert a fresh row. Considering the datatable downloaded first to be dtA, and the one that has been modified in the excel sheet to be dtB. I want to compare dtA and dtB. I need to find out all the rows in dtB that do not exist in dtA. I cant put foreach loop for each and every single row and evaluate as its a very untidy way of coding. What is a better way to do this? I did this way, DataTable dtA = new DataTable(); dtA.Columns.Add("ENo"); dtA.Columns.Add("ENo1"); dtA.Columns.Add("ENo2"); dtA.Columns.Add("ENo3"); dtA.Columns.Add("ENo4"); for (int i = 0; i < 5; i++) { DataRow dr = dtA.NewRow(); dr[0] = "Part 0 " + i.ToString(); dr[1] = "Part 1 " + i.ToString(); dr[2] = "Part 2 " + i.ToString(); dr[3] = "Part 3 " + i.ToString(); dr[4] = "Part 4 " + i.ToString(); dtA.Rows.Add(dr); } DataTable dtB = new DataTable(); dtB.Columns.Add("ENo"); dtB.Columns.Add("ENo1"); dtB.Columns.Add("ENo2"); dtB.Columns.Add("ENo3"); dtB.Columns.Add("ENo4"); for (int i = 5; i < 10; i++) { DataRow dr = dtB.NewRow(); dr[0] = "Part 0 " + i.ToString(); dr[1] = "Part 1 " + i.ToString(); dr[2] = "Part 2 " + i.ToString(); dr[3] = "Part 3 " + i.ToString(); dr[4] = "Part 4 " + i.ToString(); dtB.Rows.Add(dr); } Response.Write("\n"); Response.Write("dt A"); Response.Write("\n"); for (int i = 0; i < dtA.Rows.Count; i++) { Response.Write(dtA.Rows[i][i].ToString()); Response.Write("\n"); } Response.Write("\n"); Response.Write("dt B"); Response.Write("\n"); for (int i = 0; i < dtB.Rows.Count; i++) { Response.Write(dtB.Rows[i][i].ToString()); Response.Write("\n"); } var VarA = dtA.AsEnumerable(); var varB = dtA.AsEnumerable(); var diff = VarA.Except(varB); Response.Write("except"); foreach (var n in diff) { Response.Write(n.Table.Rows[0].ToString()); } But I do not know what to use in the foreach var, What should I use pls?

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• Designing different Factory classes (and what to use as argument to the factories!)

  - by devoured elysium

  Let's say we have the following piece of code: public class Event { } public class SportEvent1 : Event { } public class SportEvent2 : Event { } public class MedicalEvent1 : Event { } public class MedicalEvent2 : Event { } public interface IEventFactory { bool AcceptsInputString(string inputString); Event CreateEvent(string inputString); } public class EventFactory { private List<IEventFactory> factories = new List<IEventFactory>(); public void AddFactory(IEventFactory factory) { factories.Add(factory); } //I don't see a point in defining a RemoveFactory() so I won't. public Event CreateEvent(string inputString) { try { //iterate through all factories. If one and only one of them accepts //the string, generate the event. Otherwise, throw an exception. return factories.Single(factory => factory.AcceptsInputString(inputString)).CreateEvent(inputString); } catch (InvalidOperationException e) { throw new InvalidOperationException("No valid factory found to generate this kind of Event!", e); } } } public class SportEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("SportEvent1"); } public Event CreateEvent(string inputString) { return new SportEvent1(); } } public class MedicalEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("MedicalEvent1"); } public Event CreateEvent(string inputString) { return new MedicalEvent1(); } } And here is the code that runs it: static void Main(string[] args) { EventFactory medicalEventFactory = new EventFactory(); medicalEventFactory.AddFactory(new MedicalEvent1Factory()); medicalEventFactory.AddFactory(new MedicalEvent2Factory()); EventFactory sportsEventFactory = new EventFactory(); sportsEventFactory.AddFactory(new SportEvent1Factory()); sportsEventFactory.AddFactory(new SportEvent2Factory()); } I have a couple of questions: Instead of having to add factories here in the main method of my application, should I try to redesign my EventFactory class so it is an abstract factory? It'd be better if I had a way of not having to manually add EventFactories every time I want to use them. So I could just instantiate MedicalFactory and SportsFactory. Should I make a Factory of factories? Maybe that'd be over-engineering? As you have probably noticed, I am using a inputString string as argument to feed the factories. I have an application that lets the user create his own events but also to load/save them from text files. Later, I might want to add other kinds of files, XML, sql connections, whatever. The only way I can think of that would allow me to make this work is having an internal format (I choose a string, as it's easy to understand). How would you make this? I assume this is a recurrent situation, probably most of you know of any other more intelligent approach to this. I am then only looping in the EventFactory for all the factories in its list to check if any of them accepts the input string. If one does, then it asks it to generate the Event. If you find there is something wrong or awkward with the method I'm using to make this happen, I'd be happy to hear about different implementations. Thanks! PS: Although I don't show it in here, all the different kind of events have different properties, so I have to generate them with different arguments (SportEvent1 might have SportName and Duration properties, that have to be put in the inputString as argument).

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• How to map code points to unicode characters depending on the font used?

  - by Alex Schröder

  The client prints labels and has been using a set of symbolic (?) fonts to do this. The application uses a single byte database (Oracle with Latin-1). The old application I am replacing was not Unicode aware. It somehow did OK. The replacement application I am writing is supposed to handle the old data. The symbols picked from the charmap application often map to particular Unicode characters, but sometimes they don't. What looks like the Moon using the LAB3 font, for example, is in fact U+2014 (EM DASH). When users paste this character into a Swing text field, the character has the code point 8212. It was "moved" into the Private Use Area (by Windows? Java?). When saving this character to the database, Oracle decides that it cannot be safely encoded and replaces it with the dreaded ¿. Thus, I started shifting the characters by 8000: -= 8000 when saving, += 8000 when displaying the field. Unfortunately I discovered that other characters were not shifted by the same amount. In one particular font, for example, ž has the code point 382, so I shifted it by +/-256 to "fix" it. By now I'm dreading the discovery of more strange offsets and I wonder: Can I get at this mapping using Java? Perhaps the TTF font has a list of the 255 glyphs it encodes and what Unicode characters those correspond to and I can do it "right"? Right now I'm using the following kludge: static String fromDatabase(String str, String fontFamily) { if (str != null && fontFamily != null) { Font font = new Font(fontFamily, Font.PLAIN, 1); boolean changed = false; char[] chars = str.toCharArray(); for (int i = 0; i < chars.length; i++) { if (font.canDisplay(chars[i] + 0xF000)) { // WE8MSWIN1252 + WinXP chars[i] += 0xF000; changed = true; } else if (chars[i] >= 128 && font.canDisplay(chars[i] + 8000)) { // WE8ISO8859P1 + WinXP chars[i] += 8000; changed = true; } else if (font.canDisplay(chars[i] + 256)) { // ž in LAB1 Eastern = 382 chars[i] += 256; changed = true; } } if (changed) str = new String(chars); } return str; } static String toDatabase(String str, String fontFamily) { if (str != null && fontFamily != null) { boolean changed = false; char[] chars = str.toCharArray(); for (int i = 0; i < chars.length; i++) { int chr = chars[i]; if (chars[i] > 0xF000) { // WE8MSWIN1252 + WinXP chars[i] -= 0xF000; changed = true; } else if (chars[i] > 8000) { // WE8ISO8859P1 + WinXP chars[i] = (char) (chars[i] - 8000); changed = true; } else if (chars[i] > 256) { // ž in LAB1 Eastern = 382 chars[i] = (char) (chars[i] - 256); changed = true; } } if (changed) return new String(chars); } return str; }

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• Using dynamic enum as type in a parameter of a method

  - by samar

  Hi Experts, What i am trying to achieve here is a bit tricky. Let me brief on a little background first before going ahead. I am aware that we can use a enum as a type to a parameter of a method. For example I can do something like this (a very basic example) namespace Test { class DefineEnums { public enum MyEnum { value1 = 0, value2 = 1 } } class UseEnums { public void UseDefinedEnums(DefineEnums.MyEnum _enum) { //Any code here. } public void Test() { // "value1" comes here with the intellisense. UseDefinedEnums(DefineEnums.MyEnum.value1); } } } What i need to do is create a dynamic Enum and use that as type in place of DefineEnums.MyEnum mentioned above. I tried the following. 1. Used a method which i got from the net to create a dynamic enum from a list of strings. And created a static class which i can use. using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; namespace Test { public static class DynamicEnum { public static Enum finished; static List<string> _lst = new List<string>(); static DynamicEnum() { _lst.Add("value1"); _lst.Add("value2"); finished = CreateDynamicEnum(_lst); } public static Enum CreateDynamicEnum(List<string> _list) { // Get the current application domain for the current thread. AppDomain currentDomain = AppDomain.CurrentDomain; // Create a dynamic assembly in the current application domain, // and allow it to be executed and saved to disk. AssemblyName aName = new AssemblyName("TempAssembly"); AssemblyBuilder ab = currentDomain.DefineDynamicAssembly( aName, AssemblyBuilderAccess.RunAndSave); // Define a dynamic module in "TempAssembly" assembly. For a single- // module assembly, the module has the same name as the assembly. ModuleBuilder mb = ab.DefineDynamicModule(aName.Name, aName.Name + ".dll"); // Define a public enumeration with the name "Elevation" and an // underlying type of Integer. EnumBuilder eb = mb.DefineEnum("Elevation", TypeAttributes.Public, typeof(int)); // Define two members, "High" and "Low". //eb.DefineLiteral("Low", 0); //eb.DefineLiteral("High", 1); int i = 0; foreach (string item in _list) { eb.DefineLiteral(item, i); i++; } // Create the type and save the assembly. return (Enum)Activator.CreateInstance(eb.CreateType()); //ab.Save(aName.Name + ".dll"); } } } Tried using the class but i am unable to find the "finished" enum defined above. i.e. I am not able to do the following public static void TestDynEnum(Test.DynamicEnum.finished _finished) { // Do anything here with _finished. } I guess the post has become too long but i hope i have made it quite clear. Please help! Thanks in advance! Regards, Samar

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• Help with refactoring PHP code

  - by Richard Knop

  I had some troubles implementing Lawler's algorithm but thanks to SO and a bounty of 200 reputation I finally managed to write a working implementation: http://stackoverflow.com/questions/2466928/lawlers-algorithm-implementation-assistance I feel like I'm using too many variables and loops there though so I am trying to refactor the code. It should be simpler and shorter yet remain readable. Does it make sense to make a class for this? Any advice or even help with refactoring this piece of code is welcomed: <?php /* * @name Lawler's algorithm PHP implementation * @desc This algorithm calculates an optimal schedule of jobs to be * processed on a single machine (in reversed order) while taking * into consideration any precedence constraints. * @author Richard Knop * */ $jobs = array(1 => array('processingTime' => 2, 'dueDate' => 3), 2 => array('processingTime' => 3, 'dueDate' => 15), 3 => array('processingTime' => 4, 'dueDate' => 9), 4 => array('processingTime' => 3, 'dueDate' => 16), 5 => array('processingTime' => 5, 'dueDate' => 12), 6 => array('processingTime' => 7, 'dueDate' => 20), 7 => array('processingTime' => 5, 'dueDate' => 27), 8 => array('processingTime' => 6, 'dueDate' => 40), 9 => array('processingTime' => 3, 'dueDate' => 10)); // precedence constrainst, i.e job 2 must be completed before job 5 etc $successors = array(2=>5, 7=>9); $n = count($jobs); $optimalSchedule = array(); for ($i = $n; $i >= 1; $i--) { // jobs not required to precede any other job $arr = array(); foreach ($jobs as $k => $v) { if (false === array_key_exists($k, $successors)) { $arr[] = $k; } } // calculate total processing time $totalProcessingTime = 0; foreach ($jobs as $k => $v) { if (true === array_key_exists($k, $arr)) { $totalProcessingTime += $v['processingTime']; } } // find the job that will go to the end of the optimal schedule array $min = null; $x = 0; $lastKey = null; foreach($arr as $k) { $x = $totalProcessingTime - $jobs[$k]['dueDate']; if (null === $min || $x < $min) { $min = $x; $lastKey = $k; } } // add the job to the optimal schedule array $optimalSchedule[$lastKey] = $jobs[$lastKey]; // remove job from the jobs array unset($jobs[$lastKey]); // remove precedence constraint from the successors array if needed if (true === in_array($lastKey, $successors)) { foreach ($successors as $k => $v) { if ($lastKey === $v) { unset($successors[$k]); } } } } // reverse the optimal schedule array and preserve keys $optimalSchedule = array_reverse($optimalSchedule, true); // add tardiness to the array $i = 0; foreach ($optimalSchedule as $k => $v) { $optimalSchedule[$k]['tardiness'] = 0; $j = 0; foreach ($optimalSchedule as $k2 => $v2) { if ($j <= $i) { $optimalSchedule[$k]['tardiness'] += $v2['processingTime']; } $j++; } $i++; } echo '<pre>'; print_r($optimalSchedule); echo '</pre>';

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• After downloading an application with two Launcher components from the Marketplace, clicking "Open"

  - by user267728

  Create a sample application with two launcher icons. For example, two components such as: <application ...> <activity ... android:name="TestActivity01"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity ... android:name="TestActivity02"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> Either install the application via downloading from the Marketplace, or via AppInstaller. When the message box asks you if you would like to run the application, an exception is thrown: 02-03 16:42:44.270: ERROR/AndroidRuntime(395): android.content.ActivityNotFoundException: Unable to find explicit activity class {com.xxx.xxx/com.android.internal.app.ResolverActivity}; have you declared this activity in your AndroidManifest.xml? 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1 480) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1454) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.Activity.startActivityForResult(Activity.java:2660) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.Activity.startActivity(Activity.java:2704) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.packageinstaller.InstallAppDone.onClick(InstallAppDone.java:105 ) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.View.performClick(View.java:2344) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.View.onTouchEvent(View.java:4133) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.widget.TextView.onTouchEvent(TextView.java:6504) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.View.dispatchTouchEvent(View.java:3672) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEv ent(PhoneWindow.java:1712) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneW indow.java:1202) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.Activity.dispatchTouchEvent(Activity.java:1987) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(P honeWindow.java:1696) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.view.ViewRoot.handleMessage(ViewRoot.java:1658) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.os.Handler.dispatchMessage(Handler.java:99) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.os.Looper.loop(Looper.java:123) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at android.app.ActivityThread.main(ActivityThread.java:4203) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at java.lang.reflect.Method.invokeNative(Native Method) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at java.lang.reflect.Method.invoke(Method.java:521) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 791) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 02-03 16:42:44.270: ERROR/AndroidRuntime(395): at dalvik.system.NativeStart.main(Native Method) The crash happens because com.android.internal.app.ResolverActivity is trying to find a (single) component which resolves the following intent: <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> Please note that this has been tested BOTH with the AppInstaller, and the actual Marketplace on a real device.

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• What does a WinForm application need to be designed for usability, and be robust, clean, and profess

  - by msorens

  One of the principal problems impeding productivity in software implementation is the classic conundrum of “reinventing the wheel”. Of late I am a .NET developer and even the wonderful wizardry of .NET and Visual Studio covers only a portion of this challenging issue. Below I present my initial thoughts both on what is available and what should be available from .NET on a WinForm, focusing on good usability. That is, aspects of an application exposed to the user and making the user experience easier and/or better. (I do include a couple items not visible to the user because I feel strongly about them, such as diagnostics.) I invite you to contribute to these lists. LIST A: Components provided by .NET These are substantially complete components provided by .NET, i.e. those requiring at most trivial coding to use. “About” dialog -- add it with a couple clicks then customize. Persist settings across invocations -- .NET has the support; just use a few lines of code to glue them together. Migrate settings with a new version -- a powerful one, available with one line of code. Tooltips (and infotips) -- .NET includes just plain text tooltips; third-party libraries provide richer ones. Diagnostic support -- TraceSources, TraceListeners, and more are built-in. Internationalization -- support for tailoring your app to languages other than your own. LIST B: Components not provided by .NET These are not supplied at all by .NET or supplied only as rudimentary elements requiring substantial work to be realized. Splash screen -- a small window present during program startup with your logo, loading messages, etc. Tip of the day -- a mini-tutorial presented one bit at a time each time the user starts your app. Check for available updates -- facility to query a server to see if the user is running the latest version of your app, then provide a simple way to upgrade if a new version is found. Maximize to multiple monitors -- the canonical window allows you to maximize to a single monitor only; in my apps I allow maximizing across multiple monitors with a click. Taskbar notifier -- flash the taskbar when your backgrounded app has new info for the user. Options dialogs -- multi-page dialogs letting the user customize the app settings to his/her own preferences. Progress indicator -- for long running operations give the user feedback on how far there is left to go. Memory gauge -- an indicator (either absolute or percentage) of how much memory is used by your app. LIST C: Stylistic and/or tiny bits of functionality This list includes bits of functionality that are too tiny to merit being called a component, along with stylistic concerns (that admittedly do overlap with the Windows User Experience Interaction Guidelines). Design a form for resizing -- unless you are restricting your form to be a fixed size, use anchors and docking so that it does what is reasonable when enlarged or shrunk by the user. Set tab order on a form -- repeated tab presses by the user should advance from field to field in a logical order rather than the default order in which you added fields. Adjust controls to be aware of operating modes -- When starting a background operation with, for example, a “Go” button, disable that “Go” button until the operation completes. Provide access keys for all menu items (per UXGuide). Provide shortcut keys for commonly used menu items (per UXGuide). Set up some (global or important or common) shortcut keys without associating to menu items. Allow some menu items to be invoked with or without modifier keys (shift, control, alt) where the modifier key is useful to vary the operation slightly. Hook up Escape and Enter on child forms to do what is reasonable. Decorate any library classes with documentation-comments and attributes -- this allows Visual Studio to leverage them for Intellisense and property descriptions. Spell check your code! What else would you include?

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• UITextView doesn't not resize when keyboard appear if loaded from a tab bar cotroller

  - by elio.d

  I have a simple view controller (SecondViewController) used to manage a UITextview (I'm building a simple editor) this is the code of the SecondViewController.h @interface SecondViewController : UIViewController { IBOutlet UITextView *textView; } @property (nonatomic,retain) IBOutlet UITextView *textView; @end and this is the SecondViewController.m // // EditorViewController.m // Editor // // Created by elio d'antoni on 13/01/11. // Copyright 2011 none. All rights reserved. // @implementation SecondViewController @synthesize textView; /* // Implement loadView to create a view hierarchy programmatically, without using a nib. - (void)loadView { } */ // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"uiViewBg.png"]]; textView.layer.borderWidth=1; textView.layer.cornerRadius=5; textView.layer.borderColor=[[UIColor darkGrayColor] CGColor]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillAppear:) name:UIKeyboardWillShowNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillDisappear:) name:UIKeyboardWillHideNotification object:nil]; } -(void) matchAnimationTo:(NSDictionary *) userInfo { NSLog(@"match animation method"); [UIView setAnimationDuration:[[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue]]; [UIView setAnimationCurve:[[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue]]; } -(CGFloat) keyboardEndingFrameHeight:(NSDictionary *) userInfo { NSLog(@"keyboardEndingFrameHeight method"); CGRect keyboardEndingUncorrectedFrame = [[ userInfo objectForKey:UIKeyboardFrameEndUserInfoKey ] CGRectValue]; CGRect keyboardEndingFrame = [self.view convertRect:keyboardEndingUncorrectedFrame fromView:nil]; return keyboardEndingFrame.size.height; } -(CGRect) adjustFrameHeightBy:(CGFloat) change multipliedBy:(NSInteger) direction { NSLog(@"adjust method"); return CGRectMake(20, 57, self.textView.frame.size.width, self.textView.frame.size.height + change * direction); } -(void)keyboardWillAppear:(NSNotification *)notification { NSLog(@"keyboard appear"); [UIView beginAnimations:nil context:NULL]; [self matchAnimationTo:[notification userInfo]]; self.textView.frame = [self adjustFrameHeightBy:[self keyboardEndingFrameHeight: [notification userInfo]] multipliedBy:-1]; [UIView commitAnimations]; } -(void)keyboardWillDisappear:(NSNotification *) notification { NSLog(@"keyboard disappear"); [UIView beginAnimations:nil context:NULL]; [self matchAnimationTo:[notification userInfo]]; self.textView.frame = [self adjustFrameHeightBy:[self keyboardEndingFrameHeight: [notification userInfo]] multipliedBy:1]; [UIView commitAnimations]; } // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return YES; } (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } (void)dealloc { [super dealloc]; } @end the problem is that if load the view controller from a tab bar controller the textView doesn't resize when the keyboard appear, but the SAME code works if loaded as a single view based app. I hope I was clear enough. I used the tabBar template provided by xcode no modifications.

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• Database Table Schema and Aggregate Roots

  - by bretddog

  Hi, Applicaiton is single user, 1-tier(1 pc), database SqlCE. DataService layer will be (I think) : Repository returning domain objects and quering database with LinqToSql (dbml). There are obviously a lot more columns, this is simplified view. http://img573.imageshack.us/img573/3612/ss20110115171817w.png This is my first attempt of creating a 2 tables database. I think the table schema makes sense, but I need some reassurance or critics. Because the table relations looks quite scary to be honest. I'm hoping you could; Look at the table schema and respond if there are clear signs of troubles or errors that you spot right away.. And if you have time, Look at Program Summary/Questions, and see if the table layout makes makes sense to those points. Please be brutal, I will try to defend :) Program summary: a) A set of categories, each having a set of strategies (1:m) b) Each day a number of items will be produced. And each strategy MAY reference it. (So there can be 50 items, and a strategy may reference 23 of them) c) An item can be referenced by more than one strategy. So I think it's an m:m relation. d) Status values will be logged at fixed time-fractions through the day, for: - .... each Strategy.....each StrategyItem....each item e) An action on an item may be executed by a strategy that reference it. - This is logged as ItemAction (Could have called it StrategyItemAction) User Requsts b) - e) described the main activity mode of the program. To work with only today's DayLog , for each category. 2nd priority activity is retrieval of history, which typically will be From all categories, from day x to day y; Get all StrategyDailyLog. Questions First, does the overall layout look sound? I'm worried to see that there are so many relationships in all directions, connecting everything. Is this normal, or does it look like trouble? StrategyItem is made to represent an m:m relationship. Is it correct as I noted 1:m / 1:1 (marked red) ? StrategyItemTimeLog and ItemTimeLog; Logs values that both need to be retrieved together, when retreiving a StrategyItem. Reason I separated is that the first one is strategy-specific, and several strategies can reference same item. So I thought not to duplicate those values that are not dependent no strategy, but only on the item. Hence I also dragged out the LogTime, as it seems to be the only parameter to unite the logs. But this all looks quite disturbing with those 3 tables. Does it make sense at all? Or you have suggestion? Pink circles shows my vague attempt of Aggregate Root Paths. I've been thinking in terms of "what entity is responsible for delete". Though I'm unsure about the actual root. I think it's Category. Does it make sense related to User Requests described above?

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• iPhone multi-touch scale and rotate, how to prevent scale?

  - by russhill

  I have existing code for tracking multi-touch positions and then rotating and scaling the item - in this case an image - appropriately. The code works really well and in itself is perfect, however for this particular task, I need the rotation ONLY. I have spent time trying to work out what is going on in this routine, but maths is not my strong point so wanted to see if anyone could assist? - (CGAffineTransform)incrementalTransformWithTouches:(NSSet *)touches { NSArray *sortedTouches = [[touches allObjects] sortedArrayUsingSelector:@selector(compareAddress:)]; NSInteger numTouches = [sortedTouches count]; // No touches if (numTouches == 0) { return CGAffineTransformIdentity; } // Single touch if (numTouches == 1) { UITouch *touch = [sortedTouches objectAtIndex:0]; CGPoint beginPoint = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); CGPoint currentPoint = [touch locationInView:self.superview]; return CGAffineTransformMakeTranslation(currentPoint.x - beginPoint.x, currentPoint.y - beginPoint.y); } // If two or more touches, go with the first two (sorted by address) UITouch *touch1 = [sortedTouches objectAtIndex:0]; UITouch *touch2 = [sortedTouches objectAtIndex:1]; CGPoint beginPoint1 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch1); CGPoint currentPoint1 = [touch1 locationInView:self.superview]; CGPoint beginPoint2 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch2); CGPoint currentPoint2 = [touch2 locationInView:self.superview]; double layerX = self.center.x; double layerY = self.center.y; double x1 = beginPoint1.x - layerX; double y1 = beginPoint1.y - layerY; double x2 = beginPoint2.x - layerX; double y2 = beginPoint2.y - layerY; double x3 = currentPoint1.x - layerX; double y3 = currentPoint1.y - layerY; double x4 = currentPoint2.x - layerX; double y4 = currentPoint2.y - layerY; // Solve the system: // [a b t1, -b a t2, 0 0 1] * [x1, y1, 1] = [x3, y3, 1] // [a b t1, -b a t2, 0 0 1] * [x2, y2, 1] = [x4, y4, 1] double D = (y1-y2)*(y1-y2) + (x1-x2)*(x1-x2); if (D < 0.1) { return CGAffineTransformMakeTranslation(x3-x1, y3-y1); } double a = (y1-y2)*(y3-y4) + (x1-x2)*(x3-x4); double b = (y1-y2)*(x3-x4) - (x1-x2)*(y3-y4); double tx = (y1*x2 - x1*y2)*(y4-y3) - (x1*x2 + y1*y2)*(x3+x4) + x3*(y2*y2 + x2*x2) + x4*(y1*y1 + x1*x1); double ty = (x1*x2 + y1*y2)*(-y4-y3) + (y1*x2 - x1*y2)*(x3-x4) + y3*(y2*y2 + x2*x2) + y4*(y1*y1 + x1*x1); return CGAffineTransformMake(a/D, -b/D, b/D, a/D, tx/D, ty/D); } I have tried to read up on the way matrix's work, but cannot figure it out entirely. More likely to be the issue is the calculations, which as I mention is not my strong point. What I need from this routine is a transform that performs my rotation but ignores scale - so the distance between the 2 finger touch points is ignored and scale is not affected. I have looked at other routines on the internet to handle multi-touch rotation but all the ones I tried had issues in some way or other, whereas the above code is spot on for scale and rotate actions. Any help appreciated!

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• How can I provide maximum integration between a calendar-like webapp and desktop calendar applicatio

  - by Joshua Carmody

  I've been assigned to upgrade/rewrite a webapp that my company uses to schedule conference calls. One of the goals of the upgrade is to improve integration between the application and our user's Outlook calendars (and ideally other calendar programs as well). At present, when a user is viewing the details of a scheduled conference call on the webapp, they can click an "Add to Outlook calendar" link, which points them to a dynamically generated .ical file. On most of our users' systems, Outlook opens the file by default, bringing up the "create calendar appointment" window with the concall information pre-populated. This link creates a 1-time appointment only, and has to be clicked on for each occurrence of the call. So if a call happened every Monday in June, you would have to click 4 links to add all the appointments to your calendar. This is the full extent of our current level of integration. Ideally, we will be able to upgrade the system so that users can "subscribe" to a con call, which would mean not just the current call, but all calls in a reoccurring series would appear in the user's calendar with a single click. If one call in a series was cancelled, or rescheduled, that call's appointment would change in the users' calendar, without the user having to do anything, and without upsetting the rest of the series' appointments. Also, any changes to the call's info (say, the phone number was changed) would automatically be updated in the Outlook calendars of anyone who subscribed, without them having to come back to the webapp to double-check that their information is up to date. Ideally this would also work with other popular calendar programs, as well as Google Calendar. I don't know if we'll be able to achieve that level of integration, but I'd like to get as close to that as we can. Additional details and challenges: We aren't running Exchange on a public server, and I'm not likely to be able to get that changed Assume that our users are basically "the general internet public". Our users are not members of our office's network, nor can they be. We can't set up network logins or Exchange accounts for them. Some of our users are not using Outlook, but some other calendar program. Of the ones that are using Outlook, not all are using the same version. We have users in more than 50 countries that are using this webapp. Synchronization would be one-directional. Nobody can make changes in their own calendars and expect the server to reflect them/replicate them to other users Current conference calling application is written in ColdFusion. Rewrite will probably be in ASP.NET, but I haven't confirmed that yet. Solutions that work with either or both technologies are appreciated. I know that .ical files can theoretically contain more than one event, but in my own experiments I haven't had success in getting Outlook (2003) to add more than one event at a time using the .ical file method. Maybe someone knows how to set up a multi-event .ical file that Outlook will accept? Could a link to such an .ical file be "subscribed" to? Is there such thing as a calendar RSS feed? Could I simulate running an exchange server? Any other ideas? Thanks everyone!

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• Can't mass-assign protected attributes -- unsolved issue

  - by nfriend21

  I have read about 10 different posts here about this problem, and I have tried every single one and the error will not go away. So here goes: I am trying to have a nested form on my users/new page, where it accepts user-attributes and also company-attributes. When you submit the form: Here's what my error message reads: ActiveModel::MassAssignmentSecurity::Error in UsersController#create Can't mass-assign protected attributes: companies app/controllers/users_controller.rb:12:in `create' Here's the code for my form: <%= form_for @user do |f| %> <%= render 'shared/error_messages', object: f.object %> <%= f.fields_for :companies do |c| %> <%= c.label :name, "Company Name"%> <%= c.text_field :name %> <% end %> <%= f.label :name %> <%= f.text_field :name %> <%= f.label :email %> <%= f.text_field :email %> <%= f.label :password %> <%= f.password_field :password %> <%= f.label :password_confirmation %> <%= f.password_field :password_confirmation %> <br> <% if current_page?(signup_path) %> <%= f.submit "Sign Up", class: "btn btn-large btn-primary" %> Or, <%= link_to "Login", login_path %> <% else %> <%= f.submit "Update User", class: "btn btn-large btn-primary" %> <% end %> <% end %> Users Controller: class UsersController < ApplicationController def index @user = User.all end def new @user = User.new end def create @user = User.create(params[:user]) if @user.save session[:user_id] = @user.id #once user account has been created, a session is not automatically created. This fixes that by setting their session id. This could be put into Controller action to clean up duplication. flash[:success] = "Your account has been created!" redirect_to tasks_path else render 'new' end end def show @user = User.find(params[:id]) @tasks = @user.tasks end def edit @user = User.find(params[:id]) end def update @user = User.find(params[:id]) if @user.update_attributes(params[:user]) flash[:success] = @user.name.possessive + " profile has been updated" redirect_to @user else render 'edit' end #if @task.update_attributes params[:task] #redirect_to users_path #flash[:success] = "User was successfully updated." #end end def destroy @user = User.find(params[:id]) unless current_user == @user @user.destroy flash[:success] = "The User has been deleted." end redirect_to users_path flash[:error] = "Error. You can't delete yourself!" end end Company Controller class CompaniesController < ApplicationController def index @companies = Company.all end def new @company = Company.new end def edit @company = Company.find(params[:id]) end def create @company = Company.create(params[:company]) #if @company.save #session[:user_id] = @user.id #once user account has been created, a session is not automatically created. This fixes that by setting their session id. This could be put into Controller action to clean up duplication. #flash[:success] = "Your account has been created!" #redirect_to tasks_path #else #render 'new' #end end def show @comnpany = Company.find(params[:id]) end end User model class User < ActiveRecord::Base has_secure_password attr_accessible :name, :email, :password, :password_confirmation has_many :tasks, dependent: :destroy belongs_to :company accepts_nested_attributes_for :company validates :name, presence: true, length: { maximum: 50 } VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i validates :email, presence: true, format: { with: VALID_EMAIL_REGEX }, uniqueness: { case_sensitive: false } validates :password, length: { minimum: 6 } #below not needed anymore, due to has_secure_password #validates :password_confirmation, presence: true end Company Model class Company < ActiveRecord::Base attr_accessible :name has_and_belongs_to_many :users end Thanks for your help!!

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• Many-to-many mapping with LINQ

  - by Alexander

  I would like to perform LINQ to SQL mapping in C#, in a many-to-many relationship, but where data is not mandatory. To be clear: I have a news site/blog, and there's a table called Posts. A blog can relate to many categories at once, so there is a table called CategoriesPosts that links with foreign keys with the Posts table and with Categories table. I've made each table with an identity primary key, an id field in each one, if it matters in this case. In C# I defined a class for each table, defined each field as explicitly as possible. The Post class, as well as Category class, have a EntitySet to link to CategoryPost objects, and CategoryPost class has 2 EntityRef members to link to 2 objects of each other type. The problem is that a Post may relate or not to any category, as well as a category may have posts in it or not. I didn't find a way to make an EntitySet<CategoryPost?> or something like that. So when I added the first post, all went well with not a single SQL statement. Also, this post was present in the output. When I tried to add the second post I got an exception, Object reference not set to an instance of an object, regarding to the CategoryPost member. Post: [Table(Name="tm_posts")] public class Post : IDataErrorInfo { public Post() { //Initialization of NOT NULL fields with their default values } [Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)] public int ID { get; set; } private EntitySet<CategoryPost> _categoryRef = new EntitySet<CategoryPost>(); [Association(Name = "tm_rel_categories_posts_fk2", IsForeignKey = true, Storage = "_categoryRef", ThisKey = "ID", OtherKey = "PostID")] public EntitySet<CategoryPost> CategoryRef { get { return _categoryRef; } set { _categoryRef.Assign(value); } } } CategoryPost [Table(Name = "tm_rel_categories_posts")] public class CategoryPost { [Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)] public int ID { get; set; } [Column(Name = "fk_post", DbType = "int", CanBeNull = false)] public int PostID { get; set; } [Column(Name = "fk_category", DbType = "int", CanBeNull = false)] public int CategoryID { get; set; } private EntityRef<Post> _post = new EntityRef<Post>(); [Association(Name = "tm_rel_categories_posts_fk2", IsForeignKey = true, Storage = "_post", ThisKey = "PostID", OtherKey = "ID")] public Post Post { get { return _post.Entity; } set { _post.Entity = value; } } private EntityRef<Category> _category = new EntityRef<Category>(); [Association(Name = "tm_rel_categories_posts_fk", IsForeignKey = true, Storage = "_category", ThisKey = "CategoryID", OtherKey = "ID")] public Category Category { get { return _category.Entity; } set { _category.Entity = value; } } } Category [Table(Name="tm_categories")] public class Category { [Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)] public int ID { get; set; } [Column(Name = "fk_parent", DbType = "int", CanBeNull = true)] public int ParentID { get; set; } private EntityRef<Category> _parent = new EntityRef<Category>(); [Association(Name = "tm_posts_fk2", IsForeignKey = true, Storage = "_parent", ThisKey = "ParentID", OtherKey = "ID")] public Category Parent { get { return _parent.Entity; } set { _parent.Entity = value; } } [Column(Name = "name", DbType = "varchar(100)", CanBeNull = false)] public string Name { get; set; } } So what am I doing wrong? How to make it possible to insert a post that doesn't belong to any category? How to insert categories with no posts?

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• Better Way To Use C++ Named Parameter Idiom?

  - by Head Geek

  I've been developing a GUI library for Windows (as a personal side project, no aspirations of usefulness). For my main window class, I've set up a hierarchy of option classes (using the Named Parameter Idiom), because some options are shared and others are specific to particular types of windows (like dialogs). The way the Named Parameter Idiom works, the functions of the parameter class have to return the object they're called on. The problem is that, in the hierarchy, each one has to be a different class -- the createWindowOpts class for standard windows, the createDialogOpts class for dialogs, and the like. I've dealt with that by making all the option classes templates. Here's an example: template <class T> class _sharedWindowOpts: public detail::_baseCreateWindowOpts { public: /////////////////////////////////////////////////////////////// // No required parameters in this case. _sharedWindowOpts() { }; typedef T optType; // Commonly used options optType& at(int x, int y) { mX=x; mY=y; return static_cast<optType&>(*this); }; // Where to put the upper-left corner of the window; if not specified, the system sets it to a default position optType& at(int x, int y, int width, int height) { mX=x; mY=y; mWidth=width; mHeight=height; return static_cast<optType&>(*this); }; // Sets the position and size of the window in a single call optType& background(HBRUSH b) { mBackground=b; return static_cast<optType&>(*this); }; // Sets the default background to this brush optType& background(INT_PTR b) { mBackground=HBRUSH(b+1); return static_cast<optType&>(*this); }; // Sets the default background to one of the COLOR_* colors; defaults to COLOR_WINDOW optType& cursor(HCURSOR c) { mCursor=c; return static_cast<optType&>(*this); }; // Sets the default mouse cursor for this window; defaults to the standard arrow optType& hidden() { mStyle&=~WS_VISIBLE; return static_cast<optType&>(*this); }; // Windows are visible by default optType& icon(HICON iconLarge, HICON iconSmall=0) { mIcon=iconLarge; mSmallIcon=iconSmall; return static_cast<optType&>(*this); }; // Specifies the icon, and optionally a small icon // ...Many others removed... }; template <class T> class _createWindowOpts: public _sharedWindowOpts<T> { public: /////////////////////////////////////////////////////////////// _createWindowOpts() { }; // These can't be used with child windows, or aren't needed optType& menu(HMENU m) { mMenuOrId=m; return static_cast<optType&>(*this); }; // Gives the window a menu optType& owner(HWND hwnd) { mParentOrOwner=hwnd; return static_cast<optType&>(*this); }; // Sets the optional parent/owner }; class createWindowOpts: public _createWindowOpts<createWindowOpts> { public: /////////////////////////////////////////////////////////////// createWindowOpts() { }; }; It works, but as you can see, it requires a noticeable amount of extra work: a type-cast on the return type for each function, extra template classes, etcetera. My question is, is there an easier way to implement the Named Parameter Idiom in this case, one that doesn't require all the extra stuff?

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• Object validator - is this good design?

  - by neo2862

  I'm working on a project where the API methods I write have to return different "views" of domain objects, like this: namespace View.Product { public class SearchResult : View { public string Name { get; set; } public decimal Price { get; set; } } public class Profile : View { public string Name { get; set; } public decimal Price { get; set; } [UseValidationRuleset("FreeText")] public string Description { get; set; } [SuppressValidation] public string Comment { get; set; } } } These are also the arguments of setter methods in the API which have to be validated before storing them in the DB. I wrote an object validator that lets the user define validation rulesets in an XML file and checks if an object conforms to those rules: [Validatable] public class View { [SuppressValidation] public ValidationError[] ValidationErrors { get { return Validator.Validate(this); } } } public static class Validator { private static Dictionary<string, Ruleset> Rulesets; static Validator() { // read rulesets from xml } public static ValidationError[] Validate(object obj) { // check if obj is decorated with ValidatableAttribute // if not, return an empty array (successful validation) // iterate over the properties of obj // - if the property is decorated with SuppressValidationAttribute, // continue // - if it is decorated with UseValidationRulesetAttribute, // use the ruleset specified to call // Validate(object value, string rulesetName, string FieldName) // - otherwise, get the name of the property using reflection and // use that as the ruleset name } private static List<ValidationError> Validate(object obj, string fieldName, string rulesetName) { // check if the ruleset exists, if not, throw exception // call the ruleset's Validate method and return the results } } public class Ruleset { public Type Type { get; set; } public Rule[] Rules { get; set; } public List<ValidationError> Validate(object property, string propertyName) { // check if property is of type Type // if not, throw exception // iterate over the Rules and call their Validate methods // return a list of their return values } } public abstract class Rule { public Type Type { get; protected set; } public abstract ValidationError Validate(object value, string propertyName); } public class StringRegexRule : Rule { public string Regex { get; set; } public StringRegexRule() { Type = typeof(string); } public override ValidationError Validate(object value, string propertyName) { // see if Regex matches value and return // null or a ValidationError } } Phew... Thanks for reading all of this. I've already implemented it and it works nicely, and I'm planning to extend it to validate the contents of IEnumerable fields and other fields that are Validatable. What I'm particularly concerned about is that if no ruleset is specified, the validator tries to use the name of the property as the ruleset name. (If you don't want that behavior, you can use [SuppressValidation].) This makes the code much less cluttered (no need to use [UseValidationRuleset("something")] on every single property) but it somehow doesn't feel right. I can't decide if it's awful or awesome. What do you think? Any suggestions on the other parts of this design are welcome too. I'm not very experienced and I'm grateful for any help. Also, is "Validatable" a good name? To me, it sounds pretty weird but I'm not a native English speaker.

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• Make interchangeable class types via pointer casting only, without having to allocate any new objects?

  - by HostileFork

  UPDATE: I do appreciate "don't want that, want this instead" suggestions. They are useful, especially when provided in context of the motivating scenario. Still...regardless of goodness/badness, I've become curious to find a hard-and-fast "yes that can be done legally in C++11" vs "no it is not possible to do something like that". I want to "alias" an object pointer as another type, for the sole purpose of adding some helper methods. The alias cannot add data members to the underlying class (in fact, the more I can prevent that from happening the better!) All aliases are equally applicable to any object of this type...it's just helpful if the type system can hint which alias is likely the most appropriate. There should be no information about any specific alias that is ever encoded in the underlying object. Hence, I feel like you should be able to "cheat" the type system and just let it be an annotation...checked at compile time, but ultimately irrelevant to the runtime casting. Something along these lines: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Under the hood, the factory method is actually making a NodeBase class, and then using a similar reinterpret_cast to return it as a Node<AccessorFoo>*. The easy way to avoid this is to make these lightweight classes that wrap nodes and are passed around by value. Thus you don't need casting, just Accessor classes that take the node handle to wrap in their constructor: AccessorFoo foo (NodeBase::createViaFactory()); AccessorBar bar (foo.getNode()); But if I don't have to pay for all that, I don't want to. That would involve--for instance--making a special accessor type for each sort of wrapped pointer (AccessorFooShared, AccessorFooUnique, AccessorFooWeak, etc.) Having these typed pointers being aliased for one single pointer-based object identity is preferable, and provides a nice orthogonality. So back to that original question: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Seems like there would be some way to do this that might be ugly but not "break the rules". According to ISO14882:2011(e) 5.2.10-7: An object pointer can be explicitly converted to an object pointer of a different type.70 When a prvalue v of type "pointer to T1" is converted to the type "pointer to cv T2", the result is static_cast(static_cast(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are object types and where the alignment requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. The result of any other such pointer conversion is unspecified. Drilling into the definition of a "standard-layout class", we find: has no non-static data members of type non-standard-layout-class (or array of such types) or reference, and has no virtual functions (10.3) and no virtual base classes (10.1), and has the same access control (clause 11) for all non-static data members, and has no non-standard-layout base classes, and either has no non-static data member in the most-derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and has no base classes of the same type as the first non-static data member. Sounds like working with something like this would tie my hands a bit with no virtual methods in the accessors or the node. Yet C++11 apparently has std::is_standard_layout to keep things checked. Can this be done safely? Appears to work in gcc-4.7, but I'd like to be sure I'm not invoking undefined behavior.

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