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• iPhone development - app design patterns

  - by occulus

  There are tons of resources concerning coding on the iPhone. Most of them concern "how do I do X", e.g. "setup a navigation controller", or "download text from a URL". All good and fine. What I'm more interested in now are the questions that follow the simpler stuff - how to best structure your complex UI, or your app, or the common problems that arise. To illustrate: a book like "Beginning iPhone 3 Development" tells you how to set up a multi viewcontroller app with an top 'switcher' viewcontroller that switches between views owned by other view controllers. Fine, but you're only told how to do that, and nothing about the problems that can follow: for example, if I use their paradigm to switch to a UINavigationViewController, the Navigation bar ends up too low on the screen, because UINavigationViewController expects to be the topmost UIViewController (apparently). Also, delegate methods (e.g. relating to orientation changes) go to the top switcher view controller, not the actual controller responsible for the current view. I have fixes for these things but they feel like hacks which makes me unhappy and makes me feel like I'm missing something. One productive thing might be to look at some open source iPhone projects (see this question). But aside from that?

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• How do I load PersistentDocuments into the same window

  - by Brad Stone

  I want to open NSPersistentDocuments and load them into the same window one at a time. I'm almost there but missing some steps. Hopefully someone can help me. I have a few saved documents on the hard drive. On launch my app opens to an untitled NSPersistentDocument and creates a separate NSWindowController. When I press the button to load file 1 off the hard drive the data appears in the fields but two things are wrong that I can see: 1) changing the data doesn't make the document dirty 2) choosing save updates the persistentstore (I know this because when I open the file again I see the changes) but I get an error: +entityForName: could not locate an NSManagedObjectModel for entity name 'Book' Here's my code which is in the WindowController that was launched initially with the untitled document. This code isn't perfect. For example, I know I should processPendingChanges and save the current doc before I load the new one. This is test code to try to get over this hurdle. - (IBAction)newBookTwo:(id)sender { NSDocumentController *dc = [NSDocumentController sharedDocumentController]; NSURL *url = [NSURL fileURLWithPath:[@"~/Desktop/File 2.binary" stringByExpandingTildeInPath]]; NSError *error; MainWindowDocument *thisDoc = [dc openDocumentWithContentsOfURL:url display:NO error:&error]; [self setDocument:thisDoc]; [self setManagedObjectContext:[thisDoc managedObjectContext]]; } Thanks!

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• mysql get table based on common column between two tables

  - by Zentdayn

  while trying to learn sql i came across "Learn SQL The Hard Way" and i started reading it. Everything was going fine then i thought ,as a way to practice, to make something like given example in the book (example consists in 3 tables pet,person,person_pet and the person_pet table 'links' pets to their owners). I made this: report table +----+-------------+ | id | content | +----+-------------+ | 1 | bank robbery| | 2 | invalid | | 3 | cat on tree | +----+-------------+ notes table +-----------+--------------------+ | report_id | content | +-----------+--------------------+ | 1 | they had guns | | 3 | cat was saved | +-----------+--------------------+ wanted result +-----------+--------------------+---------------+ | report_id | report_content | report_notes | +-----------+--------------------+---------------+ | 1 | bank robbery | they had guns | | 2 | invalid | null or '' | | 3 | cat on tree | cat was saved | +-----------+--------------------+---------------+ I tried a few combinations but no success. My first thought was SELECT report.id,report.content AS report_content,note.content AS note_content FROM report,note WHERE report.id = note.report_id but this only returns the ones that have a match (would not return the invalid report). after this i tried adding IF conditions but i just made it worse. My question is, is this something i will figure out after getting past basic sql or can this be done in simple way? Anyway i would appreciate any help, i pretty much lost with this. Thank you. EDIT: i have looked into related questions but havent yet found one that solves my problem. I probably need to look into other statements such as join or something to sort this out.

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• Problems applying texture to a triangle strip using glTexCoordPointer

  - by Alexey

  Hi, I'm writing a pretty simple piece of code which should draw a plane. The plane must have two different textures on its sides, like if it was a book page. I'm trying to achieve this by doing this: glFrontFace(GL_CCW); glBindTexture(GL_TEXTURE_2D, textures[kActiveSideLeft]); glVertexPointer(3, GL_FLOAT, 0, vertexCoordinates); glTexCoordPointer(2, GL_FLOAT, 0, textureCoordinates); glDrawArrays(GL_TRIANGLE_STRIP, 0, (2 * kHorizontalSegmentsCount + 4) * kVerticalSegmentsCount); glFrontFace(GL_CW); glBindTexture(GL_TEXTURE_2D, textures[kActiveSideRight]); glVertexPointer(3, GL_FLOAT, 0, vertexCoordinates); glTexCoordPointer(2, GL_FLOAT, 0, textureCoordinates); glDrawArrays(GL_TRIANGLE_STRIP, 0, (2 * kHorizontalSegmentsCount + 4) * kVerticalSegmentsCount); textures[] array contains 2 GLuint textures which specify appropriate textures. vertexCoordinates and textureCoordinates contain vertexes and texture coordinates respectively ((2 * kHorizontalSegmentsCount + 4) * kVerticalSegmentsCount) equals 15 and that's exactly how many elements I have in the arrays I set up opengl like this: glEnable(GL_DEPTH_TEST); glClearDepthf(1.0f); glDepthFunc(GL_LEQUAL); glClearColor(0.0, 1.0, 1.0, 1.0); glEnable(GL_TEXTURE_2D); glEnable(GL_CULL_FACE); glCullFace(GL_BACK); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glDisableClientState(GL_NORMAL_ARRAY); glDisableClientState(GL_COLOR_ARRAY); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); What happens is when I run it front side of the plane looks Ok, but it appears like if texture coordinates weren't applied to the back side. It appears like texture on the back side is just tiled and not connected to vertexes by any means. Any idea what am I doing wrong? Or any idea about what can I do to debug this problem? Thanks.

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• What are CAD apps written in, and how are they organized ?

  - by ldigas

  What are CAD applications (Rhino, Autocad) of today written in and how are they organized internally ? I gave as an example, Autocad and Rhino, although I would love to hear of other examples as well. I'm particularly interested in knowing what is their backend written in (multilanguage ?) and how is it organized, and how do they handle their frontend (GUI) in real time ? Do they use native windows API's or some libraries of their own, since I imagine, as good as may be, the open source solutions on today's market won't cut it. I may be wrong ... As most of you who have used them know, they handle amongs other things relatively complex rotational operations in realtime (shading is not interesting me). I've been doing some experiments with several packages recently, and for some larger models found that there is considerable difference in speed in, for example, programed rotation (big full ship models) amongst some of them (which I won't name). So I'm wondering about their internals ... Also, if someone knows of some book on the subject, I'd be interested to hear of it.

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• Where can I get software-related legal advice?

  - by musicfreak

  Whenever someone asks a legal question here on SO, the response is usually something along the lines of "we are not lawyers." Okay, that's legitimate, but in that case, how can I talk to a lawyer about software-related legal matters? I could look through the phone book and find a local lawyer, but then I have no way of knowing whether the lawyer knows anything about software. (And I hear most local lawyers charge for your time, even if it's just a simple question.) Is there maybe some kind of online service for this sort of thing? For now, I'm just looking for some basic advice, so something free would be awesome, even if the "quality" is not as good. However, I'll still take any kind of paid services--I'll keep them in mind for the future. You can give me anything from a forum or QA site (like this one) to a professional service. Just remember that I'm looking specifically for software-related legal advice. I'm sure most lawyers know a thing or two about software, but I'd rather talk to someone who legitimately knows his stuff than someone who can only guess.

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• Dealing with infinite loops when constructing states for LR(1) parsing

  - by Bruce

  I'm currently constructing LR(1) states from the following grammar. S->AS S->c A->aA A->b where A,S are nonterminals and a,b,c are terminals. This is the construction of I0 I0: S' -> .S, epsilon --------------- S -> .AS, epsilon S -> .c, epsilon --------------- S -> .AS, a S -> .c, c A -> .aA, a A -> .b, b And I1. From S, I1: S' -> S., epsilon //DONE And so on. But when I get to constructing I4... From a, I4: A -> a.A, a ----------- A -> .aA, a A -> .b, b The problem is A - .aA When I attempt to construct the next state from a, I'm going to once again get the exact same content of I4, and this continues infinitely. A similar loop occurs with S -> .AS So, what am I doing wrong? There has to be some detail that I'm missing, but I've browsed my notes and my book and either can't find or just don't understand what's wrong here. Any help?

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• Generating Fibonacci Numbers Using variable-Length Arrays Code Compiler Error.

  - by Nano HE

  Compile error in vs2010(Win32 Console Application Template) for the code below. How can I fix it. unsigned long long int Fibonacci[numFibs]; // error occurred here error C2057: expected constant expression error C2466: cannot allocate an array of constant size 0 error C2133: 'Fibonacci' : unknown size Complete code attached(It's a sample code from programming In c -3E book. No any modify) int main() { int i, numFibs; printf("How may Fibonacci numbers do you want (between 1 to 75)? "); scanf("%i", &numFibs); if ( numFibs < 1 || numFibs > 75){ printf("Bad number, sorry!\n"); return 1; } unsigned long long int Fibonacci[numFibs]; Fibonacci[0] = 0; // by definition Fibonacci[1] = 1; // ditto for ( i = 2; i < numFibs; ++i) Fibonacci[i] = Fibonacci[i-2] + Fibonacci[i-1]; for ( i = 0; i < numFibs; ++i) printf("%11u",Fibonacci[i]); printf("\n"); return 0; }

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• HMAC URLs instead of login?

  - by Tres

  In implementing my site (a Rails site if it makes any difference), one of my design priorities is to relieve the user of the need to create yet another username and password while still providing useful per-user functionality. The way I am planning to do this is: User enters information on the site. Information is associated with the user via server-side session. User completes entering information, server sends an access URL via e-mail to the user roughly in the form of: http://siteurl/<user identifier>/<signature: HMAC(secret + salt + user identifier)> User clicks URL, site looks up user ID and salt and computes the HMAC with the server-stored secret and authenticates if the computed HMAC and signature match. My question is: is this a reasonably secure way to accomplish what I'm looking to do? Are there common attacks that would render it useless? Is there a compelling reason to abandon my desire to avoid a username/password? Is there a must-read book or article on the subject? Note that I'm not dealing with credit card numbers or anything exceedingly private, but I would still like to keep the information reasonably secure.

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• How to combine two separate unrelated Git repositories into one with single history timeline

  - by Antony

  I have two unrelated (not sharing any ancestor check in) Git repositories, one is a super repository which consists a number of smaller projects (Lets call it repository A). Another one is just a makeshift local Git repository for a smaller project (lets call it repository B). Graphically, it would look like this A0-B0-C0-D0-E0-F0-G0-HEAD (repo A) A0-B0-C0-D0-E0-F0-G0-HEAD (remote/master bare repo pulled & pushed from repo A) A1-B1-C1-D1-E1-HEAD (repo B) Ideally, I would really like to merge repo B into repo A with a single history timeline. So it would appear that I originally started project in repo A. Graphically, this would be the ideal end result A0-A1-B1-B0-D1-C0-D0-E0-F0-G0-E1-H(from repo B)-HEAD (new repo A) A0-A1-B1-B0-D1-C0-D0-E0-F0-G0-E1-H(from repo B)-HEAD (remote/master bare repo pulled & pushed from repo A) I have been doing some reading with submodules and subtree (Pro Git is a pretty good book by the way), but both of them seem to cater solution towards maintaining two separate branch with sub module being able to pull changes from upstream and subtree being slightly less headache. Both solution require additional and specialized git commands to handle check ins and sync between master and sub tree/module branch. Both solution also result in multiple time-lines (with --squash you even get 3 timelines with subtree). The closest solution from SO seems to talk about "graft", but is that really it? The goal is to have a single unified repository where I can pull/push check-ins, so that there are no more repo B, just repo A in the end.

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• Typical SVN repo structure seems to be sub-optimal for continuous integration...

  - by Dave

  I've set up our SVN repository like the Subversion book suggests, and this is also how my previous companies have done it. It looks something like this: /trunk /branches /tags /extlibs /docs where the first three are pretty obvious, and extlibs is for 3rd party assemblies that we wouldn't typically recompile ourselves. All of this works great for the daily development stuff. Now I've installed TeamCity and have builds, unit tests, code coverage, and code analysis running. Everything is great, except for the fact that this code structure results in too much code getting downloaded. So here's the catch 22, in my opinion: it's silly to download all of aforementioned folders from the SVN repo when I only need /trunk and /extlibs. But I can only specify one repo folder to download in the TeamCity VCS settings. So then the other possibility is to put the /extlibs folder into /trunk, but in order to compile branches, /extlibs would have to go into all of those as well (since I usually branch the trunk, and not individual subfolders... and this would seem infinitely more evil since /extlibs could actually be larger than /trunk and /branches, with all of the binaries stored there... Do you guys have any suggestions for me? Thanks!

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• Issue with class design to model user preferences for different classes

  - by Mulone

  Hi all, I'm not sure how to design a couple of classes in my app. Basically that's a situation: each user can have many preferences each preference can be referred to an object of different classes (e.g. album, film, book etc) the preference is expressed as a set of values (e.g. score, etc). The problem is that many users can have preferences on the same objects, e.g.: John: score=5 for filmid=apocalypsenow Paul: score=3 for filmid=apocalypsenow And naturally I don't want to duplicate the object film in each user. So I could create a class called "preference" holding a score and then a target object, something like: User{ hasMany preferences } Preference{ belongsTo User double score Film target Album target //etc } and then define just one target. Then I would create an interface for the target Classes (album, film etc): Interface canBePreferred{ hasMany preferences } And implement all of those classes. This could work, but it looks pretty ugly and it would requires a lot of joins to work. Do you have some patterns I could use to model this nicely? Cheers, Mulone

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• Need help extrapolating Java code

  - by Berlioz

  If anyone familiar with Rebecca Wirfs-Brock, she has a piece of Java code found in her book titled, Object Design: Roles, Responsibilities, and Collaborations. Here is the quote Applying Double Dispatch to a Specific Problem To implement the game Rock, Paper, Scissors we need to write code that determines whether one object “beats” another. The game has nine possible outcomes based on the three kinds of objects. The number of interactions is the cross product of the kinds of objects. Case or switch statements are often governed by the type of data that is being operated on. The object-oriented language equivalent is to base its actions on the class of some other object. In Java, it looks like this Here is the piece of Java code on page 16 ' import java.util.*; import java.lang.*; public class Rock { public static void main(String args[]) { } public static boolean beats(GameObject object) { if (object.getClass.getName().equals("Rock")) { result = false; } else if (object.getClass.getName().equals("Paper")) { result = false; } else if(object.getClass.getName().equals("Scissors")) { result = true; } return result; } }' ===This is not a very good solution. First, the receiver needs to know too much about the argument. Second, there is one of these nested conditional statements in each of the three classes. If new kinds of objects could be added to the game, each of the three classes would have to be modified. Can anyone share with me how to get this "less than optimal" piece of code to work in order to see it 'working'. She proceeds to demonstrate a better way, but I will spare you. Thanks

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• Drools - Doing Complex Stuff inside a Rule Condition or Consequence

  - by mfcabrera

  Hello, In my company we are planning to use Drools a BRE for couple of projects. Now we trying to define some best-practices. My question is what should be and shouldn't be done inside a Rule Condition/Consequence. Given that we can write Java directly or call methods (for example From a Global object in the Working Memory). Example. Given a Rule that evaluates a generic Object (e.g. Person) have property set to true. Now, that specific propertie can only be defined for that Object going to the database and fetching that info. So we have two ways of implementing that: Alternative A: Go to the database and fetch the object property (true/false, a code) Insert the Object in the working memory Evaluate the rule Alternative B: Insert a Global Object that has a method that connects to the database and check for the property for the given object. Insert the Object to eval in Working Memory In the rule, call the Global Object and perform the access to the database Which of those is considered better? I really like A, but sometimes B is more straightforward, however what would happen if something like a Exception from the Database is raised? I have seen the alternative B implemented in the Drools 5.0 Book from Packt Publishing,however they are doing a mocking and they don't talk about the actual implications of going to the database at all. Thank you,

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• Constructor initializer list: code from the C++ Primer, chapter 16

  - by Alexandros Gezerlis

  Toward the end of Chapter 16 of the "C++ Primer" I encountered the following code (I've removed a bunch of lines): class Sales_item { public: // default constructor: unbound handle Sales_item(): h() { } private: Handle<Item_base> h; // use-counted handle }; My problem is with the Sales_item(): h() { } line. For the sake of completeness, let me also quote the parts of the Handle class template that I think are relevant to my question (I think I don't need to show the Item_base class): template <class T> class Handle { public: // unbound handle Handle(T *p = 0): ptr(p), use(new size_t(1)) { } private: T* ptr; // shared object size_t *use; // count of how many Handles point to *ptr }; I would have expected something like either: a) Sales_item(): h(0) { } which is a convention the authors have used repeatedly in earlier chapters, or b) Handle<Item_base>() if the intention was to invoke the default constructor of the Handle class. Instead, what the book has is Sales_item(): h() { }. My gut reaction is that this is a typo, since h() looks suspiciously similar to a function declaration. On the other hand, I just tried compiling under g++ and running the example code that uses this class and it seems to be working correctly. Any thoughts?

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• uploading database file in assets not returning a record

  - by Alexander

  I have a problem with a database file not being read I have added the database file in assets called mydb but when i run my code it says its not being located. It is calling this toast Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show(); This is being called because no records are being returned. This is an example form Android Application Development book. public class DatabaseActivity extends Activity { /** Called when the activity is first created. */ TextView quest, response1, response2; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView quest = (TextView) findViewById(R.id.quest); try { String destPath = "/data/data/" + getPackageName() + "/databases/MyDB"; File f = new File(destPath); if (!f.exists()) { CopyDB( getBaseContext().getAssets().open("mydb"), new FileOutputStream(destPath)); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } DBAdapter db = new DBAdapter(this); //---get a contact--- db.open(); Cursor c = db.getContact(2); if (c.moveToFirst()) DisplayContact(c); else Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show(); db.close(); } public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException { //---copy 1K bytes at a time--- byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer)) > 0) { outputStream.write(buffer, 0, length); } inputStream.close(); outputStream.close(); } public void DisplayContact(Cursor c) { quest.setText(String.valueOf(c.getString(1))); //quest.setText(String.valueOf("this is a text string")); } }

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• Using Enum in Hibernate causes select followed by an update statement

  - by Leonardo

  Hi all, I have a mapped entity wich has an enum property. By loking at log file, whenever I run a select statement on such entity, the result is an immediately following update. For example if my result set contains 100 records, then I have: [INFO org... select...] [INFO org... update... where id=?] [INFO org... update... where id=?] .... repeated 100 times If I mark the property as update=false the problem disappear. The enum is assigned trough an enum converter class, which I copied from a well known book. So I don't know if I just copy and paste the code. Here it is how is declared on hbm file. <typedef class="mypackage.HbnEnumConverter" name="the_type"> <param name="enumClassname">mypackage.TheType</param> </typedef> Can you point out a direction to investigate this ? Beside, what are the consequences of having update=false on hibernate field ? thanks

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• Is this state-of-the-art Ajax/jQuery, or should I do it differently?

  - by AP257

  Hi everyone: I'm using Ajax and jQuery to do some cool client-side stuff. Basically, if the user chooses a subject from a from a drop-down list, I want to auto-populate the page with a set of book details. However, I've built the Ajax from Google results and bits of string. I don't know if what I've done is up-to-date, or whether there are now much neater ways of doing it! Here's what I have: can it be improved? $("#subjectlist").change(function() { if (window.XMLHttpRequest) { xmlhttp=new XMLHttpRequest(); } else { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { var book_details = eval(xmlhttp.responseText); alert(book_details[0]["url"]); // To be added: extra code to populate HTML results. document.getElementById("book_results").innerHTML=xmlhttp.responseText; } } xmlhttp.open("GET","/subject_json/?id=" + $("#subjectlist").val(),true); xmlhttp.send(); }); Thanks for any advice!

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• Strange Access Denied warning when running the simplest C++ program.

  - by DaveJohnston

  I am just starting to learn C++ (coming from a Java background) and I have come across something that I can't explain. I am working through the C++ Primer book and doing the exercises. Every time I get to a new exercise I create a new .cpp file and set it up with the main method (and any includes I think I will need) e.g.: #include <list> #include <vector> int main(int argc, char **args) { } and just to make sure I go to the command prompt and compile and run: g++ whatever.cpp a.exe Normally this works just fine and I start working on the exercise, but I just did it and got a strange error. It compiles fine, but when I run it it says Access Denied and AVG pops up telling me that a threat has been detected 'Trojan Horse Generic 17.CKZT'. I tried compiling again using the Microsoft Compiler (cl.exe) and it runs fines. So I went back, and added: #include <iostream> compiled using g++ and ran. This time it worked fine. So can anyone tell me why AVG would report an empty main method as a trojan horse but if the iostream header is included it doesn't?

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• Google Apps Script: how to make suggest box library to work?

  - by Pythonista's Apprentice

  I'm trying to add an autocomplete feature in my Google Spreadsheet using this Google Apps Script suggest box library from Romain Vialard and James Ferreira's book: function doGet() { // Get a list of all my Contacts var contacts = ContactsApp.getContacts(); var list = []; for(var i = 0; i < contacts.length; i++){ var emails = contacts[i].getEmails(); if(emails[0] != undefined){ list.push(emails[0].getAddress()); } } var app = UiApp.createApplication(); var suggestBox = SuggestBoxCreator.createSuggestBox(app, 'contactPicker', 200, list); app.add(suggestBox); return app; } function onEdit() { var s = SpreadsheetApp.getActiveSheet(); if( s.getName() == "my_sheet_name" ) { //checks that we're on the correct sheet var r = s.getActiveCell(); if( r.getColumn() == 1) { doGet(); } } } But when I start editing the column 1 of "my_sheet_name" nothing hapens (if I replace doGet() for other function, this other function runs Ok). I've already installed the Suggest Box library. So, why the doGet() function doesn't work?

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• How to get a debug flow of execution in C++

  - by Rich

  Hi, I work on a global trading system which supports many users. Each user can book,amend,edit,delete trades. The system is regulated by a central deal capture service. The deal capture service informs all the user of any updates that occur. The problem comes when we have crashes, as the production environment is impossible to re-create on a test system, I have to rely on crash dumps and log files. However this doesn't tell me what the user has been doing. I'd like a system that would (at the time of crashing) dump out a history of what the user has been doing. Anything that I add has to go into the live environment so it can't impact performance too much. Ideas wise I was thinking of a MACRO at the top of each function which acted like a stack trace (only I could supply additional user information, like trade id's, user dialog choices, etc ..) The system would record stack traces (on a per thread basis) and keep a history in a cyclic buffer (varying in size, depending on how much history you wanted to capture). Then on crash, I could dump this history stack. I'd really like to hear if anyone has a better solution, or if anyone knows of an existing framework? Thanks Rich

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• Questions on Juval Lowy's IDesign C# Coding Standard

  - by Jan

  We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

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• LINQ-to-SQL - Join, Count

  - by ile

  I have following query: var result = ( from role in db.Roles join user in db.Users on role.RoleID equals user.RoleID where user.CreatedByUserID == userID orderby user.FirstName ascending select new UserViewModel { UserID = user.UserID, PhotoID = user.PhotoID.ToString(), FirstName = user.FirstName, LastName = user.LastName, FullName = user.FirstName + " " + user.LastName, Email = user.Email, PhoneNumber = user.Phone, AccessLevel = role.Name }); Now, I need to modify this query... Other table I have is table Deals. I would like to count how many deals user created last month and last year. I tried something like this: var result = ( from role in db.Roles join user in db.Users on role.RoleID equals user.RoleID //join dealsYear in db.Deals on date.Year equals dealsYear.DateCreated.Year join dealsYear in ( from deal in db.Deals group deal by deal.DateCreated into d select new { DateCreated = d.Key, dealsCount = d.Count() } ) on date.Year equals dealsYear.DateCreated.Year into dYear join dealsMonth in ( from deal in db.Deals group deal by deal.DateCreated into d select new { DateCreated = d.Key, dealsCount = d.Count() } ) on date.Month equals dealsMonth.DateCreated.Month into dMonth where user.CreatedByUserID == userID orderby user.FirstName ascending select new UserViewModel { UserID = user.UserID, PhotoID = user.PhotoID.ToString(), FirstName = user.FirstName, LastName = user.LastName, FullName = user.FirstName + " " + user.LastName, Email = user.Email, PhoneNumber = user.Phone, AccessLevel = role.Name, DealsThisYear = dYear, DealsThisMonth = dMonth }); but here is even syntax not correct. Any idea? Btw, is there any good book of LINQ to SQL with examples?

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• Strange data swapping error occurs when I attempt to update rows in my table from another table in m

  - by Wesley

  So I have a table of data that is 10,000 lines long. Several of the columns in the table simply describe information about one of the columns, meaning, that only one column has the content, and the rest of the columns describe the location of the content (its for a book). Right now, only 6,000 of the 10,000 rows' content column is filled with its content. Rows 6-10,000's content column simply says null. I have another table in the db that has the content for rows 6,000-10,000, with the correct corresponding primary key which would (seemingly) make it easy to update the 10,000 row table. I have been trying an update query such as the following: UPDATE table(10,000) SET content_column = (SELECT content FROM table(6,000-10,000) WHERE table(10,000).id = table(6-10,000.id) Which kind of works, the only problem is that it pulls in the data from the second table just fine, but it replaces the existing content column with null. So rows 1-6,000's content column become null, and rows 6-10,000's content column have the correct values...Pretty strange I thought anyway. Does anybody have any thoughts about where I am going wrong? If you could show me a better sql query, I would appreciate it! Thanks

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• Web Applications Development: Security practices for Application design

  - by Shyam

  Hi, As I am creating more web applications that are targeted for multiple users, I figured out that I have to start thinking about user management and security. At a glance and in my ideal world, all users belong to a group. Permissions and access is thus defined per group (and inherited by the users of that group). Logically, I have my group of administrators, which are identified with a level "7" (integer) clearance. A group of webusers have for example level "1". This in generally all works great for me, but I need some kind of list that I have to keep in mind how I secure my system, and some general practices. I am not looking for a specific environment; I want to learn the why's and how's. An example is privilege escalation. If someone would be able to "push" themselves inside a group with higher privileges, for example the Administration, how can I prevent this, or what measures should I take to have some sort of precaution? I don't like in that case to walk into a caveat. My question is basically: where can I find a good resource, list, policy, book that explains the security of web applications, the why's, the how's and readable if you don't have any experience in the realm of advanced security? I prefer a free resource, as I believe I couldn't be the first one who thought about this. Thank you for your answers, comments and feedback.

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