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• Are C++ Templates just Macros in disguise?

  - by Roddy

  I've been programming in C++ for a few years, and I've used STL quite a bit and have created my own template classes a few times to see how it's done. Now I'm trying to integrate templates deeper into my OO design, and a nagging thought keeps coming back to me: They're just a macros, really... You could implement (rather UGLY) auto_ptrs using #defines, if you really wanted to. This way of thinking about templates helps me understand how my code will actually work, but I feel that I must be missing the point somehow. Macros are meant evil incarnate, yet "template metaprogramming" is all the rage. So, what ARE the real distinctions? and how can templates avoid the dangers that #define leads you into, like Inscrutable compiler errors in places where you don't expect them? Code bloat? Difficulty in tracing code? Setting Debugger Breakpoints?

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• Delphi: How to assign dynamically an event handler without overwriting the existing event handler?

  - by user193655

  I need to loop through Components and assign an event handler (for example Dynamically assigning OnClick event for all TButton to ShowMessage('You clicked on ' + (Sender as TButton).Name); The problem is that in some cases I alreasy assigned the TButton OnClick event. Is there a way to solve the problem? Let's imagine I have Button1 for which the harcoded onclick event handler is: ShowMessage('This is Button1'); After my "parsing" I would like that the full event handler for Button1 becomes: ShowMessage('This is Button1'); // design time event handler code ShowMessage('You clicked on ' + (Sender as TButton).Name); // runtime added Note: I am looking for a soliution that allows me to use TButton as it is without inheriting from it.

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• Logging to screen and to a file

  - by robUK

  What design pattern might apply to logging? What is normally used in this type of situation? Any good tutorials? I am writing a client-server application using C89 and gcc 4.4.4. I now need to implement some logging feature that will display log messages on the screen as well as log to a file. However, I don't want to display all log messages (warning, error, critical, unrecoverable, debug, etc). Maybe I can set so that it will display just errors and nothing else. For example, the user might not be interested in the debug messages on the screen output.

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• T-SQL Self Join in combination with aggregate function

  - by Nick

  Hi, i have the following table. CREATE TABLE [dbo].[Tree]( [AutoID] [int] IDENTITY(1,1) NOT NULL, [Category] [varchar](10) NULL, [Condition] [varchar](10) NULL, [Description] [varchar](50) NULL, CONSTRAINT [PK_Tree] PRIMARY KEY CLUSTERED ( [AutoID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO the data looks like this: INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('1','Alpha','Type 1') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('1','Alpha','Type 1') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('2','Alpha','Type 2') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('2','Alpha','Type 2') go I try now to do the following: SELECT Category,COUNT(*) as CategoryCount FROM Tree where Condition = 'Alpha' group by Category but i wish also to get the Description for each Element. I tried several subqueries, self joins etc. i always come to the problem that the subquery cannot return more than one record. The problem is caused by a poor database design which i cannot change and i run out of ideas to get this done in a single query ;-(

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• C#, Manage concurrency in database access

  - by Goul

  Hi there, I have written a while ago an application used by multiple users to handle trades creation. I haven't done development for some time now and can't remember how I managed the concurrency between the users and so would have liked your advices in term of design. The application was as follow: - One heavy client per user - A single database - Access to the database for each user to insert/update/delete trades - A grid in the application reflecting the trades table. That grid being updated each time someone changes a deal. My questions: 1- Do you confirm I shouldn't care about the connection to the database for each application. Considering that there is a singleton in each, I would expect on connexion per client with no issue. 2- How preventing the concurrency of the accesses? I guess I should lock when modifying the data, however don't remember how to. 3- How to have the grid automatically updated whenever the database is (by another user for example)? Thank you in advance for your help!

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• Which language should I learn to create a sudoku game?

  - by Brandan

  I'd like to learn a new programming language, something besides all the scripting languages I've used for the past many years (Ruby, JavaScript, Perl, PHP, bash). I figured it might be interesting to make a sudoku game since there are plenty of documented algorithms and it only requires fairly simple data structures. It might start out as either a generator or a solver of puzzles, not necessarily both and not necessarily with a GUI. My goal is primarily to learn some new programming concepts beyond MVC and UI design, secondarily for this thing to be pretty fast. Is there a language that particularly shines for these sorts of constraint satisfaction problems? Is it suited to a functional language like Haskell or a highly concurrent language like Erlang (say for solving puzzles much larger than 9 x 9)? Or is this question mostly meaningless?

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• Web GUI frameworks for Phone development

  - by Runner

  I looked already and could't find anyting good. So a question is, are there any good web frameworks that would allow to easily develop GUI for the majority of high end phones? By this I mean It would have to work the same on majority of high end phones (forget the low cost ones) It would have to simplify the development and hide the ugly details from developer Clear design and good documentation. Also some stability on the market. The focus in on good looking and easy to make GUI. Javascript is only a plus. So basically I am looking for something like jQuery or maybe ExtJS for phone development. EDIT: It would be a big plus if it could be consumed in Delphi EDIT 2: If it was not clear, I am looking for a web base solution. So the target is HTML output and not native code.

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• Scala puts precedence on implicit conversion over "natural" operations... Why? Is this a bug? Or am

  - by Alex R

  This simple test, of course, works as expected: scala var b = 2 b: Int = 2 scala b += 1 scala b res3: Int = 3 Now I bring this into scope: class A(var x: Int) { def +=(y:Int) { this.x += y } } implicit def int2A(i:Int) : A = new A(i) I'm defining a new class and a += operation on it. I never expected this would affect the way my regular Ints behave. But it does: scala var b:Int = 0 b: Int = 0 scala b += 1 scala b res29: Int = 0 scala b += 2 scala b res31: Int = 0 Scala seems to prefer the implicit conversion over the natural += that is already defined to Ints. That leads to several questions... Why? Is this a bug? Is it by design? Is there a work-around (other than not using "+=")? Thanks

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• How do I "think in AngularJS" if I have a jQuery background?

  - by Mark Rajcok

  How do I “think in AngularJS” if I have a jQuery background? Suppose I'm familiar with developing client-side applications in jQuery, but now I'd like to start using AngularJS. Can you describe the paradigm shift that is necessary? Here are a few questions that might help you frame an answer: How do I architect and design client-side web applications differently? What is the biggest difference? What should I stop doing/using; what should I start doing/using instead? Are there any server-side considerations/restrictions? I'm not looking for a detailed comparison between jQuery and AngularJS.

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• linq2sql left join with "multiselect"

  - by just_azho

  Hi, folks I'm trying to achieve following by linq2sql, but not successful. I've Member and Reference tables. DB is design in such a manner that Member can have multiple (=0) References. What I want as a result of query is, list (rows) of members, where all references of the member are "collected" in one column. What I had achieved is following query, but for this one there exist a row for each Reference. var refs = (from m in db.Members join r in db.References on m.PID equals r.PID into g from o in g.DefaultIfEmpty() select new { member = m, name = (o == null ? "" : o.NameSurname) }); I feel I need to insert SelectMany somewher :) Could you please give hints on achieving the goal?

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• VS 2008, is there a way to search properties like the old vb6/EVB? CTRL+SHIFT?

  - by Davery

  I really miss the CTRL+SHIFT+CHAR searching of a property in VS 2008 that older IDE's had... typing CTRL+SHIFT+T got you to "tabindex" then Tag when pressed again. They dropped it in VS 2002 I believe, and the closest I could find to restoring any functionality like it was acorn's property window filter, which isn't exactly functional. Does anyone know of a way to get this functionality back? I hate having to browse through 30-40 properties in design mode, when a CTRL+SHIFT+T would get me right to text. Thanks!

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• How to pass sockets created to another Java Process

  - by whoi

  Hi; We have an application which creates many sockets which belongs to its thread, By design if this application somehow fails, all threads stop which is not wanted. So to overcome this issue, each thread must be separated from the main application, if one of the threads fails, the other ones should be running. One thing in our mind is to pass created socket to another java process, so what is the correct way? An other approach also is welcome? Waiting for your suggestions...

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• One Database Field to Hold Survey Answer

  - by yar

  Skipping the question of whether this is bad design (and the question of why I would want/need to do this), I'm just wondering if my 'math' is right... I have n things that need to be put in order (n is always less than 5): thing1 thing2 thing3 ... and I'd like to store these results in a single integer for thing. My initial thought is that (obviously the code will not look like this): thing = thing1 * 1 + thing2 * 2 + thing3 * 4 + thing5 * 8 will always give me a unique value, and that any value for thing will always translate back to its values for thing1...thingn. Is this correct?

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• Continuously reading from a stream in C#?

  - by Damien Wildfire

  I have a Stream object that occasionally gets some data on it, but at unpredictable intervals. Messages that appear on the Stream are well-defined and declare the size of their payload in advance (the size is a 16-bit integer contained in the first two bytes of each message). I'd like to have a StreamWatcher class which detects when the Stream has some data on it. Once it does, I'd like an event to be raised so that a subscribed StreamProcessor instance can process the new message. Can this be done with C# events without using Threads directly? It seems like it should be straightforward, but I can't get quite get my head around the right way to design this.

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• Why is this consider bad practice? or is it? (ASP.Net)

  - by user318573

  Would this code be considered bad practice: <div id="sidebar"> <% =DisplayMeetings(12) %> </div> This is a snippet of code from the default.aspx of a small web app I have worked on. It works perfectly well, runs very fast, but as always, I am aware of the fact that just because it works, doesn't mean it is OK. Basically, the DisplayMeetings subroutine outputs a bunch of formatted HTML (an unordered list actually), with no formatting, just the requisite html, and then my CSS performs all the necessary formatting. The data for generating the list comes from an SQL server database (the parameter controls how many rows to return) and I am using stored procedures and datareader for fast access. This keeps my front-end extraordinary simple and clean, imho, and lets me do all the work in VB or C# in a separate module. I could of course use a databound repeater (and probably 6 or more other methods) of accomplishing the same thing, but are they any better? Other than loosing the design-time features of VS2010?

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• create logging so that the messages will be displayed on screen and logged to a file

  - by robUK

  Hello, gcc 4.4.4 c89 I am writing a client/server application. I have finished and now I want to implement some logging feature that will display log messages on the screen as well as log to a file. However, I don't want to display all log messages (warning, error, critical, unrecoverable, debug, etc). Maybe I can set so that it will display, just errors and debug messages and nothing else. For example, the user might not be interested in the debug messages. Is there any design-pattern that I can follow? What do you normally for for logging? Any tutorials out there that address logging? many thanks for any suggestions,

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• need a virtual template member workaround

  - by yurib

  Hello, I need to write a program implementing the visitor design pattern. The problem is that the base visitor class is a template class. This means that BaseVisited::accept() takes a template class as a parameter and since it uses 'this' and i need 'this' to point to the correct runtime instance of the object, it also needs to be virtual. I'd like to know if there's any way around this problem. template <typename T> class BaseVisitor { public: BaseVisitor(); T visit(BaseVisited *visited); virtual ~BaseVisitor(); } class BaseVisited { BaseVisited(); template <typename T> virtual void accept(BaseVisitor<T> *visitor) { visitor->visit(this); }; // problem virtual ~BaseVisited(); }

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• Getting age from an encrypted DOB field

  - by Mailforbiz

  Hi all Due to certain compliance requirements, we have to encrypt the user DOB field in the database. We also have another requirement to be able to search a user by his age. Our DB doesn't support transparent encryption so encryption will handled by the application. Any good ideas on how to allow for searching by age? One thought is to save the YOB in a separate column in cleartext and still be able to comply to our compliance requirement. Aside from that, any other design strategy that would help? Thanks in advance!

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• Drupal vs FatWire - Any thoughts?

  - by RadiantHex

  Hi folks, a company I am working for is considering the usage of a CMS, apparently two of the suggested CMSs are Drupal and FatWire. FatWire is proprietary and quite expensive, therefore it seems that there is a not so big community build around the product. Functionality seems to be extensive, even though a few design choices seem counter-intuitive and long-winded. Drupal instead is open source and has an big community backing the product. There are plenty of books around and usage seems more intuitive. Functionality wise I am unsure on how they compare. The main features that the company's team seem to like are team workflow features and revision control (present in FatWire, even though the implementation seems quite limited). Hopefully some of you guys have been faced with these two products before, and might have a few suggestions up their sleeve. Help would be much appreciated!

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• titleForHeaderInSection is not updating Section Header information correctly

  - by Jim

  I have two tableviews where one navigates to the next. Both use more or less the same code and use the managedObjectContext and FetchedResultsController design pattern to provide the relevant data for both tables. My problem happens when I navigate from the first to the second tableview and the data has only one Section Header / Row in the tableview. The data will then not update Section Header information. It does when there is more than one row but not if there is only one row. It leaves the information from the first attempt in place. I can confirm the row data is correct so the relevant data should be being passed to the Section Header correctly but it isn't. Has anyone else come across this problem?

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• Why are Objective-C instance variables declared in an interface?

  - by Chase

  I'm just getting into Objective-C (Java is my primary OO language). Defining an object's instance variables in the interface instead of the class seems strange. I'm used to an interface being a public API definition with nothing besides method signatures (not counting constants here). Is there some reason that state is defined in an interface (even if it is private) and behaviour is defined in a class. It just seems odd that since objects are state+behavior that the definition would be split into two separate places. Is it a design benefit is some way? A pain in the rear issue that you are just forced to deal with in Objective-C? A non-issue, just different? Any background on why it's done this way? Or can you put object state in a class and I just haven't hit that part in my book yet?

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• How do I remove a control if not a specific type?

  - by joek1975

  I have a control that I need to restrict the types of child controls that it can contain during design time (dragging a new control onto an existing control on the form designer). I tried to do this by overriding the OnControlAdded event: Protected Overrides Sub OnControlAdded(ByVal e As System.Windows.Forms.ControlEventArgs) MyBase.OnControlAdded(e) If e.Control.GetType() IsNot GetType(ExpandablePanel) Then MsgBox("You can only add the ExpandablePanel control to the TaskPane.", MsgBoxStyle.Exclamation Or MsgBoxStyle.OkOnly, "TaskPane") Controls.Remove(e.Control) End If End Sub This seems to work, however I get an error message from Visual Studio immediately after the control is removed: 'child' is not a child control of this parent. What does this mean? How can I accomplish this without errors occurring?

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• Is there a way to only have StyleCop documenation requirements SA1600 on public methods/properties?

  - by AlSki

  I've been using XMLDoc for a few years now, and have definitely grown into the mindset for supplying quality documentation for public methods and properties. However under StyleCop (and particularly its Resharper highlighting) I've noticed that the documentation requirements apply to identically to public, internal, protected and private methods. This seems a little counter-intuative to me, so I would ideally like to suppress it down to suggestions at least for private methods. Unfortunately it does seem as if the suppress setting is only across all public, internal, private, etc. Am I missing something or is this by design?

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• Python configuration file generator

  - by Stan

  I want to use Python to make a configuration file generator. My roughly idea is feeding input with template files and some XML files with the real settings. Then use the program to generate the real configuration files. I got several questions: Is there any open source configuration generator program? (what could be the keyword), I wonder if there's anything can be added/modified in the design. Does Python have good XML parser module? Is it good idea to use XML file to save the original settings? I've been thinking to use Excel since it's more intuitive to maintain, but harder for program to parse. Not sure how people deal with this. Hope the community can give me some suggestions. Thanks a lot!

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• Loading XML with possible infinite tags

  - by Firstmate

  (I'm doing this in AS3, but I'm sure the answer could be given in psuedocode) Basically, I have a XML file similar to: <Main> <Event> <Name>Blah</Name> <Event> Name>Blah2</Name> <Event> <Name>Blah3</Name> ... </Event> </Event> </Event> </Main> Yeah, to some extent it's poor design. But the idea I'm going for is that any Event has the potential to compromise of other Events and this idea kinda loops. Any ideas on how to do this?

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