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• Intercept creation of activities when the application is restored

  - by Johan Bilien

  Most of our activities access a user-specific model. All these activities inherit from a ModelActivity base class, which provides a getModel() call. When one of these activities detect that the user has signed out (through the AccountManager callback), it sticks to its existing model, but prepares to exit back to the root activity (which is not user-specific) by starting its intent with FLAG_ACTIVITY_CLEAR_TOP. If however the user deletes an account while the app is not running, we run into trouble when the activity is restored. Now the activity needs to handle there not being a model, which makes the code more complicated and bug-prone. Ideally we would intercept the application restore process before the activity is created. Then we would check whether we have an account and a model, and if not clear up the saved stack of activities, and restart from our root activity instead of the last saved activity. But as far as I can tell the first place where we can run code is in the onCreate callback of the activity. Is there a way to run some code when the application is restored from background-saving, but before the saved activity is created?

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• C++ Dynamic object construction

  - by Rajesh Subramanian

  I have a base class, class Msg { ParseMsg() { ParseMsgData(); ParseTrailer(); } virtual void ParseMsgData() = 0; ParseTrailer(); }; and derived classes, class InitiateMsg { void ParseMsgData() { ... } }; class ReadOperationMsg { void ParseMsgData() { ... } }; class WriteOperationMsg { void ParseMsgData() { ... } }; and the scenario is below, void UsageFunction(string data) { Msg* msg = ParseHeader(data); ParseMsg } Msg* ParseHeader(string data) { Msg *msg = NULL; .... switch() { case 1: msg = new InitiateMsg(); break; case 2: msg = new ReadOperationMsg{(); break; case 3: msg = new WriteOperationMsg{(); break; .... } return msg; } based on the data ParseHeader method will decide which object has to be created, So I have implemented ParseHeader function outside the class where I am using. How can I make the ParseHeader function inside the Msg class and then use it? In C# the same is achieved by defining ParseHeader method as static with in class and use it from outside,

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• File name containing more than 16 characters inside parentheses failing

  - by Tom anMoney

  I am generating file names that contain a timestamp in the following format: "base_name (yyyy-mm-dd hhmmss).ext" This seems to cause a problem on Android. Here's my log: /storage/sdcard0/anMoney/transfer/Net worth over time _ Forecast (2012-11-19 110550).pdf E/Gmail (11802): java.io.FileNotFoundException: /storage/sdcard0/myapp/transfer/Net worth over time _ Forecast (2012-11-19 110550).pdf: open failed: ENOENT (No such file or directory) E/Gmail (11802): at libcore.io.IoBridge.open(IoBridge.java:416) E/Gmail (11802): at java.io.FileInputStream.<init>(FileInputStream.java:78) E/Gmail (11802): at java.io.FileInputStream.<init>(FileInputStream.java:105) E/Gmail (11802): at android.content.ContentResolver.openInputStream(ContentResolver.java:445) E/Gmail (11802): at com.google.android.gm.provider.MailEngine.cacheAttachment(MailEngine.java:3054) E/Gmail (11802): at com.google.android.gm.provider.MailEngine.sendOrSaveDraft(MailEngine.java:2746) E/Gmail (11802): at com.google.android.gm.provider.MailProvider.sendOrSaveDraft(MailProvider.java:477) E/Gmail (11802): at com.google.android.gm.provider.MailProvider.insert(MailProvider.java:534) E/Gmail (11802): at android.content.ContentProvider$Transport.insert(ContentProvider.java:201) E/Gmail (11802): at android.content.ContentResolver.insert(ContentResolver.java:864) E/Gmail (11802): at com.google.android.gm.provider.Gmail$MessageModification.sendOrSaveNewMessage(Gmail.java:3576) E/Gmail (11802): at com.google.android.gm.ComposeActivity$SendOrSaveTask$1.onInitializationComplete(ComposeActivity.java:1765) E/Gmail (11802): at com.google.android.gm.provider.MailEngine$5.run(MailEngine.java:1006) E/Gmail (11802): at android.os.Handler.handleCallback(Handler.java:615) E/Gmail (11802): at android.os.Handler.dispatchMessage(Handler.java:92) E/Gmail (11802): at android.os.Looper.loop(Looper.java:137) E/Gmail (11802): at android.os.HandlerThread.run(HandlerThread.java:60) E/Gmail (11802): Caused by: libcore.io.ErrnoException: open failed: ENOENT (No such file or directory) Now, if I trim the file name to have only 16 characters within the parentheses, everything is working as expected. I am able to send the file as a GMail attachment. The following file name is working fine: /storage/sdcard0/myapp/transfer/Net worth over time _ Forecast (2012-11-19 11070).pdf I tried the following troubleshooting: It's not the overall length of the file name, as if I shorten the base name, the same behavior remains It's not GMail, uploading the file to Google Drive fails similarly 16 characters inside the parentheses work, but not 17 It's not the space character inside the parentheses that causes the issue, as I replaced it with a dash and it's the same problem. Anybody has any ideas on what's going on here?

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• Why Is the sender type null when dealing with events

  - by ChloeRadshaw

  From C# Via CLR: Note A lot of people wonder why the event pattern requires the sender parameter to always be of type Object After all, since the MailManager will be the only type raising an event with a NewMail EventArgs object, it makes more sense for the callback method to be prototyped like this: void MethodName(Mai l Manager sender, NewMail EventArgs e); The pattern requires the sender parameter to be of type Object mostly because of inheritance What if Mai lManager were used as a base class for SmtpMailManager? In this case, the callback method should have the sender parameter prototyped as SmtpMailManager instead of Mail Manager, but this can’t happen because SmtpMai lManager just inherited the NewMai l event So the code that was expecting SmtpMail Manager to raise the event must still have to cast the sender argument to SmtpMailManager In other words, the cast is still required, so the sender parameter might as well be typed as Obj ect The next reason for typing the sender parameter as Obj ect is just fexibility It allows the delegate to be used by multiple types that offer an event that passes a NewMail EventArgs object For example, a PopMai lManager class could use the delegate even if this class were not derived from Mail Manager I just simply cannot understand why the sender is an object - Why can it not be generified? so most of the time we do not need to do generic casts

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• How to make cycle over cycles in Java?

  - by Roman

  I would like to make a cycle over the following elements: [1,2,11,12,21,22,111,112,121,122,....,222222] or for example [1,2,3,11,12,13,21,22,23,31,32,33,111,112,113,... 333333333] How can I make it in Java? In my particular case I use 4 digits (1,2,3,4) and the length of the last number can be from 1 to 10. I managed to do it in Python and PHP. In the first case I used list over lists. I started from [[1],[2],] then for every element of the list I added 1 and 2, so I got [[1,1],[1,2],[2,1],[2,2]] and so on: nchips = sum(chips) traj = [[]] last = [[]] while len(last[0]) < nchips: newlast = [] for tr in last: for d in [1,2,3,4]: newlast.append(tr + [d]) last = newlast traj += last When I did it in PHP I used number with base 3. But it was a tricky and non elegant solution. for ($i=-1; $i<=$n; $i+=1) { if ($i>-1) { $n5 = base_convert($i,10,5); $n5_str = strval($n5); $tr = array(); $found = 0; for ($j=0; $j<strlen($n5_str); $j+=1) { $k = $n5_str[$j]; if ($k==0) { $found = 1; break; } array_push($tr,$k); } if ($found==1) continue; } else { $tr = array(); } } Can it be done easily in Java?

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• C++: inheritance problem

  - by Helltone

  It's quite hard to explain what I'm trying to do, I'll try: Imagine a base class A which contains some variables, and a set of classes deriving from A which all implement some method bool test() that operates on the variables inherited from A. class A { protected: int somevar; // ... }; class B : public A { public: bool test() { return (somevar == 42); } }; class C : public A { public: bool test() { return (somevar > 23); } }; // ... more classes deriving from A Now I have an instance of class A and I have set the value of somevar. int main(int, char* []) { A a; a.somevar = 42; Now, I need some kind of container that allows me to iterate over the elements i of this container, calling i::test() in the context of a... that is: std::vector<...> vec; // push B and C into vec, this is pseudo-code vec.push_back(&B); vec.push_back(&C); bool ret = true; for(i = vec.begin(); i != vec.end(); ++i) { // call B::test(), C::test(), setting *this to a ret &= ( a .* (&(*i)::test) )(); } return ret; } How can I do this? I've tried two methods: forcing a cast from B::* to A::*, adapting a pointer to call a method of a type on an object of a different type (works, but seems to be bad); using std::bind + the solution above, ugly hack; changing the signature of bool test() so that it takes an argument of type const A& instead of inheriting from A, I don't really like this solution because somevar must be public.

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• highlight listview items android

  - by user1752939

  I have listview with custom base adapter. When I populate the list I have to check a boolean in the object I'm populating the listview and if it is true to change the background color of that row. public View getView(int position, View convertView, ViewGroup parent) { LoginsList entry = listOfLoginsLists.get(position); if (convertView == null) { LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); convertView = inflater.inflate(R.layout.lists_row, null); } TextView ListName = (TextView) convertView.findViewById(R.id.tvListName); ListName.setText(entry.getListName()); TextView ListDescription = (TextView) convertView.findViewById(R.id.tvListDescription); ListDescription.setText(entry.getListDescription()); Button Send = (Button) convertView.findViewById(R.id.bSend); Send.setOnClickListener(this); Send.setTag(entry); RelativeLayout RelLayout = (RelativeLayout) convertView.findViewById(R.id.layoutListsRow); RelLayout.setFocusableInTouchMode(false); RelLayout.setFocusable(false); RelLayout.setOnClickListener(this); RelLayout.setTag(entry); if (entry.isSent()) { RelLayout.setBackgroundColor(Color.parseColor("#4400FF00")); } return convertView; } But this code doesn't work right. When I scroll the list view the rows colors get messed up.

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• Deleting list items via ProcessBatchData()

  - by q-tuyen

  You can build a batch string to delete all of the items from a SharePoint list like this: 1: //create new StringBuilder 2: StringBuilder batchString= new StringBuilder(); 3: 4: //add the main text to the stringbuilder 5: batchString.Append(""); 6: 7: //add each item to the batch string and give it a command Delete 8: foreach (SPListItem item in itemCollection) 9: { 10: //create a new method section 11: batchString.Append(""); 12: //insert the listid to know where to delete from 13: batchString.Append("" + Convert.ToString(item.ParentList.ID) + ""); 14: //the item to delete 15: batchString.Append("" + Convert.ToString(item.ID) + ""); 16: //set the action you would like to preform 17: batchString.Append("Delete"); 18: //close the method section 19: batchString.Append(""); 20: } 21: 22: //close the batch section 23: batchString.Append(""); 24: 25: //preform the batch 26: SPContext.Current.Web.ProcessBatchData(batchString.ToString()); The only disadvantage that I can think of right know is that all the items you delete will be put in the recycle bin. How can I prevent that? I also found the solution like below: // web is a the SPWeb object your lists belong to // Before starting your deletion web.Site.WebApplication.RecycleBinEnabled = false; // When your are finished re-enable it web.Site.WebApplication.RecycleBinEnabled = true; Ref [Here](http://www.entwicklungsgedanken.de/2008/04/02/how-to-speed-up-the-deletion-of-large-amounts-of-list-items-within-sharepoint/) But the disadvantage of that solution is that only future deletion will not be sent to the Recycle Bins but it will delete all existing items as well which user do not want. Any idea to prevent not to delete existing items? Many thanks in advance, TQT

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• Freeing of allocated memory in Solaris/Linux

  - by user355159

  Hi, I have written a small program and compiled it under Solaris/Linux platform to measure the performance of applying this code to my application. The program is written in such a way, initially using sbrk(0) system call, i have taken base address of the heap region. After that i have allocated an 1.5GB of memory using malloc system call, Then i used memcpy system call to copy 1.5GB of content to the allocated memory area. Then, I freed the allocated memory. After freeing, i used again sbrk(0) system call to view the heap size. This is where i little confused. In solaris, eventhough, i freed the memory allocated (of nearly 1.5GB) the heap size of the process is huge. But i run the same application in linux, after freeing, i found that the heap size of the process is equal to the size of the heap memory before allocation of 1.5GB. I know Solaris does not frees memory immediately, but i don't know how to tune the solaris kernel to immediately free the memory after free() system call. Also, please explain why the same problem does not comes under Linux? Can anyone help me out of this? Thanks, Santhosh.

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• PDFBox Pagebreak strange Nullpointer exception

  - by schneiti

  I currently try printing out text on multiple pages. For this, I count the number of rows and when they reach a fixed amount a method called pagebreakis executed. After the first pagebreak, when I try setting a font using contentstream.setFont(PDType1Font.HELVETICA, 12); it yields the following errormessage occuring at the described setFont-row. java.lang.NullPointerException at org.apache.pdfbox.pdmodel.edit.PDPageContentStream.setFont(PDPageContentStream.java:321) at com.xy.deu.xy.abc.db.schemavergleich.PDFDocumenter.drawBGCS(PDFDocumenter.java:781) at com.xy.deu.xy.abc.db.schemavergleich.PDFDocumenter.createPDFDocumentation(PDFDocumenter.java:205) at com.xy.deu.xy.abc.db.schemavergleich.MainClass.createPDFandOutput(MainClass.java:361) at com.xy.deu.xy.abc.db.schemavergleich.MainClass.start(MainClass.java:231) at com.xy.deu.xy.abc.db.schemavergleich.MainClass.main(MainClass.java:180) Below is the code that gets executed as the error occurs. ... // If Table gets to long for a page -> pagebreak: if(currentLines > 37) { pageBreak(currentLinePos); // TODO Currently causing app to crash } ... private void pageBreak(int currentLine) throws Exception { contentStream.endText(); contentStream.close(); // Create new page page = new PDPage(PDPage.PAGE_SIZE_A4); doc.addPage( page ); // Create a new font object selecting one of the PDF base fonts font = PDType1Font.HELVETICA; // Start a new content stream which will "hold" the to be created content contentStream = new PDPageContentStream(doc, page); currentLines = 0; mediabox = page.findMediaBox(); contentStream.beginText(); contentStream.moveTextPositionByAmount(startX, startY); contentStream.setFont(PDType1Font.HELVETICA, 12); } Now comes the strange thing: Debugging yields into nothing that is not set. I'll attach a screenshot for you right at the position where the error occurs:

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• Array's index and argc signedness

  - by tusbar

  Hello, The C standard (5.1.2.2.1 Program startup) says: The function called at program startup is named main. [...] It shall be de?ned with a return type of int and with no parameters: int main(void) { /* ... */ } or with two parameters [...] : int main(int argc, char *argv[]) { /* ... */ } And later says: The value of argc shall be nonnegative. Why shouldn't argc be defined as an unsigned int, argc supposedly meaning 'argument count'? Should argc be used as an index for argv? So I started wondering if the C standard says something about the type of array's index. Is it signed? 6.5.2.1 Array subscripting: One of the expressions shall have type ‘‘pointer to object type’’, the other expression shall have integer type, and the result has type ‘‘type’’. It doesn't say anything about its signedness (or I didn't find it). It is pretty common to see codes using negatives array indexes (array[-1]) but isn't it undefined behavior? Should array's indexes be unsigned?

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• C ++ virtual function

  - by user2950788

  masters of C++. I am trying to implement polymorphism in C++. I want to write a base class with a virtual function and then redefine that function in the child class. then demonstrate dynamic binding in my driver program. But I just couldn't get it to work. I know how to do it in C#, so I figured that I might have made some syntactical mistakes where I had used C#'s syntax in my C++ code, but these mistakes are not obvious to me at all. So I'd greatly appreciate it if you would correct my mistakes. class polyTest { public: polyTest(); virtual void type(); virtual ~polyTest(); }; void polyTest::type() { cout << "first gen"; } class polyChild: public polyTest { public: void type(); }; void polyChild::type() { cout << "second gen"; } int main() { polyChild * ptr1; polyChild * ptr2; ptr1 = new polyTest(); ptr2 = new polyChild(); ptr1 -> type(); ptr2 -> type(); }

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• Passing user_id, site_id, and question_id to same table on create...

  - by bgadoci

  I can't seem to figure out how to do this. I am trying to pass four different variables to a single table. To be more specific I am trying to create a "like" in a likes table that also captures the site_id (like an answer), user_id, and the question_id. Here is the set up. class Like < ActiveRecord::Base belongs_to :site belongs_to :user belongs_to :question end I will spare you the reverse, has_many associations but they are there. Here is the likes controller where I think the problem is. class LikesController < ApplicationController def create @user = current_user @site = Site.find(params[:site_id]) @like = @site.likes.create!(params[:like]) @like.user = current_user @like.save respond_to do |format| format.html { redirect_to @site} format.js end end end This code successfully passes the like and site_id but after many different variations of trying I can't get it to pass the question id. Here is my form: /views/sites/_site.html.erb (though the partial is being displayed in the /views/questions/show.html.erb file). <% remote_form_for [site, Like.new] do |f| %> <%= f.hidden_field :site_name, :value => "#{site.name}" %> <%= f.hidden_field :ip_address, :value => "#{request.remote_ip}" %> <%= f.hidden_field :like, :value => "1" %> <%= submit_tag "^" , :class => 'voteup' %> <% end %>

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• Client Server communication in Java - which approach to use?

  - by markovuksanovic

  I have a typical client server communication - Client sends data to the server, server processes that, and returns data to the client. The problem is that the process operation can take quite some time - order of magnitude - minutes. There are a few approaches that could be used to solve this. Establish a connection, and keep it alive, until the operation is finished and the client receives the response. Establish connection, send data, close the connection. Now the processing takes place and once it is finished the server could establish a connection to the client to send the data. Establish a connection, send data, close the connection. Processing takes place. client asks server, every n minutes/seconds if the operation is finished. If the processing is finished the client fetches the data. I was wondering which approach would be the best way to use. Is there maybe some "de facto" standard for solving this problem? How "expensive" is opening a socket in Java? Solution 1. seems pretty nasty to me, but 2. and 3. could do. The problem with solution 2. is that the server needs to know on which port the client is listening, while solution 3. adds some network overhead.

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• Exemplars of large document-centric applications with COM/XPCOM/.NET interfaces.

  - by Warren P

  I am looking for exemplars (design examples) showing the use of interfaces (aka 'protocols' for you smalltalkers) to design a document management architecture in a large Word Processor, Spreadsheet, vector graphic or publishing package, or office-productivity (non-database) application with support for as many of the following as possible: any open source project, will be ideal, and language of implementation is unimportant since I am looking for design examples, however an object oriented language with support for "interfaces" is a must. I know at least a dozen languages, and I'm willing to study any application's source. use of "interface" could loosely be applied to either XPCOM or COM interfaces, or .NET interfaces, or even the use of pure-virtual (virtual+abstract) base-classes for OOP languages that lack the ability to declare an interface distinct from a class. I am mostly looking for a robust, thorough and flexible implementation for a document, IDocument, various document views (IDocumentView), and whatever operations make sense in that case. I am particular interested in cases where the product in question is a real-world product. For example, if anybody familiar with OpenOffice can tell me if the code contains a good sample design. I am looking for design documentation that outlines the design of the interfaces for such an application. So for example, if the openoffice spreadsheet has such an interface design, then that might be the best case, because it is a widely used real-world design, with millions of users, rather than a textbook example, which is minimal, and contrived. I know that the Mozilla platform uses XPCOM, and its design is heavily "interface" oriented, but I am looking more for a "word processor" or "spreadsheet" type of document design, rather than a web-browser. I am particularly interested in the interfaces used to access to data and meta-data such as markup (attributes like bold, and italics, and font size), and the ability to search and look up named entities within a document.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• The sign of zero with float2

  - by JackOLantern

  Consider the following code performing operations on complex numbers with C/C++'s float: float real_part = log(3.f); float imag_part = 0.f; float real_part2 = (imag_part)*(imag_part)-(real_part*real_part); float imag_part2 = (imag_part)*(real_part)+(real_part*imag_part); The result will be real_part2= -1.20695 imag_part2= 0 angle= 3.14159 where angle is the phase of the complex number and, in this case, is pi. Now consider the following code: float real_part = log(3.f); float imag_part = 0.f; float real_part2 = (-imag_part)*(-imag_part)-(real_part)*(real_part); float imag_part2 = (-imag_part)*(real_part)+(real_part)*(-imag_part); The result will be real_part2= -1.20695 imag_part2= 0 angle= -3.14159 The imaginary part of the result is -0 which makes the phase of the result be -pi. Although still accomplishing with the principal argument of a complex number and with the signed property of floating point's 0, this changes is a problem when one is defining functions of complex numbers. For example, if one is defining sqrt of a complex number by the de Moivre formula, this will change the sign of the imaginary part of the result to a wrong value. How to deal with this effect?

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• query not displaying proper result

  - by ravindra

  In my Rails 3 project I have the following code for My controller: class TasksController < ApplicationController def today @tasks = Task.today @task = Task.new respond_to do |format| format.html { render :text=> "Sorry , you don't have any task pending today." } format.html # new.html.erb format.xml { render :xml => @tasks } end end def this_week @tasks = Task.this_week @task = Task.new respond_to do |format| format.html { render :text => "Sorry , No content for selected period." } format.html # new.html.erb format.xml { render :xml => @tasks } end end end My model: class Task < ActiveRecord::Base def self.today Task.where(:due_date => "Date.today" , :task_status => "open").order("due_date ASC") end def self.this_week Task.where(:due_date =>"Time.now.this_week" , :task_status => "open" ).order("due_date ASC") end end Why it does not displaying anything in the relative view. Please help me. Thanks

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• RoR ActiveRecord f.select nil method error

  - by sellis6688

  Whenever I use an f.select statement to determine assignment_id(or student_id), and I should get a validation error, I get this error instead of the validation message: You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.collect Extracted source (around line #11): 8: </p> 9: <p> 10: <%= f.label 'Assignment:' %><br /> 11: <%= f.select(:assignment_id, @assignments.collect {|p| [p.ass_num, p.id]})%> 12: </p> 13: <p> 14: <%= f.label 'First Student:' %><br /> My grades model: class Grade < ActiveRecord::Base has_and_belongs_to_many :students belongs_to :assignment validates_presence_of :score, :assignment_id, :student_id validates_numericality_of :score, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 100, :allow_nil => true validates_uniqueness_of :student_id, :scope => :assignment_id end If I use a text_field, I don't get the error... but there's far too many students for that. Neither @assignments nor @students are nil. Any suggestions?

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• trouble with custom 'Text Bubble' component (examples included)

  - by gmoniey

  I'm trying to use a custom Text component to show a series of comments. I got the original idea from: http://www.eonflex.com/?p=40 I've got the base case working but I am stuck with 2 problems I cant seem to figure out: Since I am drawing around the text, the actual height of each bubble is greater than that of the Text field, as a result, the last bubble is always chopped off. I have tried explicitly overriding the height getter, and adding some padding, but I cant seem to get it right. You can see an example here: http://test.lambandtunafish.com/bubbles/CommentTest.swf In my layout, I have 2 VBoxes (one nested inside the other). The first vbox shows a form where the user can enter a comment, and the second box has all the comments. In order to ensure that the scrollbars only show up on the second box, I set minHeight="0" on the nested VBox, but then for some reason, some comments' text is shifted to the right. You can see an example here (look at the first comment): http://test.lambandtunafish.com/bubbles/CommentTest-minHeight.swf Rather than posting the code here, I've provided some links: Container: http://test.lambandtunafish.com/bubbles/CommentTest.mxml Bubble: http://test.lambandtunafish.com/bubbles/CommentBubble.as If anyone has any ideas, I would appreciate it. Thanks!

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• Handling large (object) datasets with PHP

  - by Aron Rotteveel

  I am currently working on a project that extensively relies on the EAV model. Both entities as their attributes are individually represented by a model, sometimes extending other models (or at least, base models). This has worked quite well so far since most areas of the application only rely on filtered sets of entities, and not the entire dataset. Now, however, I need to parse the entire dataset (IE: all entities and all their attributes) in order to provide a sorting/filtering algorithm based on the attributes. The application currently consists of aproximately 2200 entities, each with aproximately 100 attributes. Every entity is represented by a single model (for example Client_Model_Entity) and has a protected property called $_attributes, which is an array of Attribute objects. Each entity object is about 500KB, which results in an incredible load on the server. With 2000 entities, this means a single task would take 1GB of RAM (and a lot of CPU time) in order to work, which is unacceptable. Are there any patterns or common approaches to iterating over such large datasets? Paging is not really an option, since everything has to be taken into account in order to provide the sorting algorithm.

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• HLSL - Combining textures

  - by b34r

  Hi All, I'm trying to combine two textures in HLSL - specifically, I want to take the alpha values from a base image, and the color data from an overlay image. My pixel shader for this looks like this: float4 PixelShaderFunction(VertexOut input) : COLOR0 { float4 baseColor = tex2D( BaseSampler, input.baseCoords.xy ).rgba; float4 overlayColor = tex2D( OverlaySampler, input.overlayCoords.xy ).rgba; float4 color; color.r = overlayColor.r; color.g = overlayColor.g; color.b = overlayColor.b; color.a = baseColor.a; return color.rgba; } and my blend state looks like this: BlendState bs = new BlendState(); bs.AlphaSourceBlend = Blend.SourceAlpha; bs.AlphaDestinationBlend = Blend.DestinationAlpha; bs.ColorSourceBlend = Blend.SourceColor; bs.ColorDestinationBlend = Blend.DestinationColor; What this leaves me with is a washed out version of what should be the overlay color. I've tried numerous permutations of the BlendState settings, and played with the pixel shader math quite a bit, but to no avail. Can anyone point me in the right direction? Thanks in advance =)

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• Ruby on Rails: custom instance creation failing at redirect

  - by Jack

  I am at an absolute loss as to what I am doing wrong with the following code. I am trying to implement a messaging system within my application, but want it to be handle different types of messages. In this case, I want to create a "request" message of ':message_type = 1'. Instead of using forms as I usually have, I want to make this instance the moment the link is clicked. Here is how I have it set up in the show erb file for "user": <%=link_to "Send friend request", :action=>"request", :controller => "messages", :id => @user.id %> and in the controller: def request @message = Message.new(:sender_id => current_user.id,:user_id => params[:id],:message_type => 1) if @message.save flash[:notice] = 'Message was successfully created.' redirect_to message_path(@message) else redirect_to message_path(@message) end end This results in the following error message: undefined method `rewrite' for nil:NilClass with the trace looking like c:/ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/whiny_nil.rb:52:in `method_missing' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:634:in `url_for' (eval):16:in `message_path' app/controllers/messages_controller.rb:11:in `request' I have used map.resources :messages in the routes.rb file, and done the appropriate :has_many and :belongs_to associations in the models of user and message.

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