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  • Generate unique ID from multiple values with fault tolerance

    - by ojreadmore
    Given some values, I'd like to make a (pretty darn) unique result. $unique1 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8', '0plnmjfys')); //now $unique1 == "sqef3452y"; I also need something that's pretty close to return the same result. In this case, 20% of the values is missing. $unique2 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8')); //also $unique2 == "sqef3452y"; I'm not sure where to begin with such an algorithm but I have some assumptions. I assume that the more values given, the more accurate the resulting ID – in other words, using 20 values is better than 5. I also assume that a confidence factor can be calculated and adjusted. What would be nice to have is a weight factor where one can say 'value 1 is more important than value 3'. This would require a multidimensional array for input instead of one dimension. I just mashed on the keyboard for these values, but in practice they may be short or long alpha numeric values.

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  • Inheritence and usage of dynamic_cast

    - by Mewzer
    Hello, Suppose I have 3 classes as follows (as this is an example, it will not compile!): class Base { public: Base(){} virtual ~Base(){} virtual void DoSomething() = 0; virtual void DoSomethingElse() = 0; }; class Derived1 { public: Derived1(){} virtual ~Derived1(){} virtual void DoSomething(){ ... } virtual void DoSomethingElse(){ ... } virtual void SpecialD1DoSomething{ ... } }; class Derived2 { public: Derived2(){} virtual ~Derived2(){} virtual void DoSomething(){ ... } virtual void DoSomethingElse(){ ... } virtual void SpecialD2DoSomething{ ... } }; I want to create an instance of Derived1 or Derived2 depending on some setting that is not available until run-time. As I cannot determine the derived type until run-time, then do you think the following is bad practice?... class X { public: .... void GetConfigurationValue() { .... // Get configuration setting, I need a "Derived1" b = new Derived1(); // Now I want to call the special DoSomething for Derived1 (dynamic_cast<Derived1*>(b))->SpecialD1DoSomething(); } private: Base* b; }; I have generally read that usage of dynamic_cast is bad, but as I said, I don't know which type to create until run-time. Please help!

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  • How can I skip some block content while reading in Perl.

    - by Nano HE
    Hello. I plan to skip the block content which include the start line of "MaterializeU4()" with the subroutin() read_block below. But failed. # Read a constant definition block from a file handle. # void return when there is no data left in the file. # Otherwise return an array ref containing lines to in the block. sub read_block { my $fh = shift; my @lines; my $block_started = 0; while( my $line = <$fh> ) { # how to correct my code below? I don't need the 2nd block content. $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 0) ) ; if( $block_started ) { last if $line =~ /^\s*$/; push @lines, $line; } } return \@lines if @lines; return; } Data as below: __DATA__ status DynTest = <dynamic 100> vid = 10002 name = "DynTest" units = "" status VIDNAME9000 = <U4 MaterializeU4()> vid = 9000 name = "VIDNAME9000" units = "degC" status DynTest = <U1 100> vid = 100 name = "Hello" units = "" Output: <StatusVariables> <SVID logicalName="DynTest" type="L" value="100" vid="10002" name="DynTest" units=""></SVID> <SVID logicalName="VIDNAME9000" type="L" value="MaterializeU4()" vid="9000" name="VIDNAME9000" units="degC"></SVID> <SVID logicalName="DynTest" type="L" value="100" vid="100" name="Hello" units=""></SVID> </StatusVariables> [Updated] I print the value of index($line, "MaterializeU4"), it output 25. Then I updated the code as below $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 25) Now it works. Any comments are welcome about my practice. Thank you.

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  • Is it acceptable to wrap PHP library functions solely to change the names?

    - by Carson Myers
    I'm going to be starting a fairly large PHP application this summer, on which I'll be the sole developer (so I don't have any coding conventions to conform to aside from my own). PHP 5.3 is a decent language IMO, despite the stupid namespace token. But one thing that has always bothered me about it is the standard library and its lack of a naming convention. So I'm curious, would it be seriously bad practice to wrap some of the most common standard library functions in my own functions/classes to make the names a little better? I suppose it could also add or modify some functionality in some cases, although at the moment I don't have any examples (I figure I will find ways to make them OO or make them work a little differently while I am working). If you saw a PHP developer do this, would you think "Man, this is one shoddy developer?" Additionally, I don't know much (or anything) about if/how PHP is optimized, and I know that usually PHP performace doesn't matter. But would doing something like this have a noticeable impact on the performance of my application?

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  • Flowcharting functional programming languages

    - by Sadface
    Flowcharting. This ancient old practice that's been in use for over 1000 years now, being forced upon us poor students, without any usefulness (or so do I think). It might work well with imperative, sequentially running languages, but what about my beloved functional programming? Sadly, I'm forced to create a flow chart for my programm (that is written in Haskell). I imagine it being easy for something like this: main :: IO () main = do someInput <- getLine let upped = map toUpper someInput putStrLn upped Which is just 3 sequenced steps, fetching data, uppercasing it, outputting it. Things look worse this time: main :: IO () main = do someInput <- fmap toUpper getLine putStrLn someInput Or like this: main :: IO () main = interact (map toUpper) Okay, that was IO, you can handle that like an imperative language. What about pure functions? An actual example: onlyMatching :: String -> [FilePath] -> [FilePath] onlyMatching ext = filter f where f name = lower ('.' : ext) == (lower . takeExtension $ name) lower = map toLower How would you flowchart that last one?

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  • Grails - Where to store properties related to domains

    - by GalmWing
    This is something I have been struggling about for some time now. The thing is: I have many (20 or so) static arrays of values. I say static because that is how I'm actually storing them, as static arrays inside some domains. For example, if I have a list of known websites, I do: class Website { ... static websites = ["web1", "web2" ...] } But I do this just while developing, because I can easily change the arrays if needed, but what I'm going to do when the application is ready for deployment? In my project it is very probable that, at some point, these arrays of values change. I've been researching on that matter, one can store application properties inside an external .properties file, but it will be impossible to store an array, even futile, because if some array gets an additional value, the application can't recognize it until the name of the new property is added where needed. Another approach is to store this information in the database, but for some reason it seems like a waste to add 20 or more tables that will have just two rows, an id and a name. And the last option, as far as I know, would be an XML, but I'm not very experienced with those. It seems groovy has a way of creating and reading XML files relatively easy, but I don't know how difficult would be to modify an XML whose layout is predefined in the application. Needless to say that storing them in the config.groovy is not an option since any change will require to recompile. I haven't come across some "standard" (maybe a best practice?) way of dealing with these. So the questions is: Where to store these arrays?

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  • How to efficiently implement a strategy pattern with spring ?

    - by Anth0
    I have a web application developped in J2EE 1.5 with Spring framework. Application contains "dashboards" which are simple pages where a bunch of information are regrouped and where user can modify some status. Managers want me to add a logging system in database for three of theses dashboards. Each dashboard has different information but the log should be traced by date and user's login. What I'd like to do is to implement the Strategy pattern kind of like this : interface DashboardLog { void createLog(String login, Date now); } // Implementation for one dashboard class PrintDashboardLog implements DashboardLog { Integer docId; String status; void createLog(String login, Date now){ // Some code } } class DashboardsManager { DashboardLog logger; String login; Date now; void createLog(){ logger.log(login,now); } } class UpdateDocAction{ DashboardsManager dbManager; void updateSomeField(){ // Some action // Now it's time to log dbManagers.setLogger = new PrintDashboardLog(docId, status); dbManagers.createLog(); } } Is it "correct" (good practice, performance, ...) to do it this way ? Is there a better way ? Note :I did not write basic stuff like constructors and getter/setter.

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  • How do I put my return data from an asmx into JSON?

    - by jphenow
    I want to return an array of javascript objects from my asp.net asmx file. ie. variable = [ { *value1*: 'value1', *value2*: 'value2', ..., }, { . . } ]; I seem have been having trouble reaching this. I'd put this into code but I've been hacking away at it so much it'd probably do more harm than good in having this answered. Basically I am using a web service to find names as people type the name. I'd use a regular text file or something but its a huge database that's always changing - and don't worry I've indexed the names so searching can be a little snappier - but I would really prefer to stick with this method and just figure out how to get usable JSON back to javascript. I've seen a few that sort of attempt to describe how one would approach this but I honestly think microsofts articles are damn near unreadable. Thanks in advance for assistance. EDIT: I'm using the $.ajax() function from jQuery - I've had it working but it seems like I was doing it in bad practice not returning and using actual JSON. Previously I'd take a string back and insert it into html to use the variable it set - very roundabout.

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  • Using delegate Types vs methods

    - by Grant Sutcliffe
    I see increasing use of the delegate types offered in the System namespace (Action; Predicate etc). As these are delegates, my understanding is that they should be used where we have traditionally used delegates in the past (asynchronous calls; starting threads, event handling etc). Is it just preference or is it considered practice to use these delegate types in scenarios such as the below; rather than using calls to methods we have declared (or anonymous methods): public void MyMethod { Action<string> action = delegate(string userName { try { XmlDocument profile = DataHelper.GetProfile(userName); UpdateMember(profile); } catch (Exception exception) { if (_log.IsErrorEnabled) _log.ErrorFormat(exception.Message); throw (exception); } }; GetUsers().ForEach(action); } At first, I found the code less intuitive to follow than using declared or anonymous methods. I am starting to code this way, and wonder what the view are in this regard. The example above is all within a method. Is this delegate overuse.

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  • Releasing from development into production in maven

    - by Bruce
    Hi all, I'm confused about the use of maven in development and production environments - I'm sure it's something simple that I'm missing. Grateful for any help.. I set up maven inside eclipse on my local machine and wrote some software. I really like how it's made things like including dependent jars very easy. So that's my development environment. But now I want to release the project to production on a remote server. I've searched the documentation, but I can't figure out how it's supposed to work or what the maven best practice is.. Are you supposed to: a) Also be running maven on your production environment, and upload all your files to your production environment and rebuild your project there? (Something in me baulks at the idea of rebuilding 'released' code on the production server, so I'm fairly sure this isn't right..) b) use mvn:package to create your jar file and then copy that up to production? (But then what of all those nice dependencies? Isn't there a danger that your tested code is now going to be running against different versions of the dependent jars in the production environment, possibly breaking your code? Or missing a jar..?) c) Something else that I'm not figuring out.. Thanks in advance for any help!

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  • Why is short project lifetime and other situation-specific reasons used to excuse crappy code? [clos

    - by sharptooth
    Every now and then (including on SO) people say things implying that "if the project is short lived you can leave obvious defects there" or "that memory leak only accounts for 100 bytes per whole program lifetime and could be left". Now in my practice I always reuse company-owned code to the greatest extent I can. Like if I need something and I can find it in the company codebase I take it from there and reuse or adapt. This means that any crappy code will be reused as well and I might notice or not notice defects therein. So the defect in some "test we only need for a month" can slip into a proram we ship to customers. And a leak that "only accounted for 100 bytes per lifetime" now could account for 100 bytes 10 times per second in a server application intended to run for months. That's why I don't understand why excuses like that are offered. Is our compamy the only one having a source control? Or are we the only company that requires writing human-readable code? Could anyone shed a light on why people seriously offer such excuses?

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  • List all foreign key constraints that refer to a particular column in a specific table

    - by Sid
    I would like to see a list of all the tables and columns that refer (either directly or indirectly) a specific column in the 'main' table via a foreign key constraint that has the ON DELETE=CASCADE setting missing. The tricky part is that there would be an indirect relationships buried across up to 5 levels deep. (example: ... great-grandchild- FK3 = grandchild = FK2 = child = FK1 = main table). We need to dig up the leaf tables-columns, not just the very 1st level. The 'good' part about this is that execution speed isn't of concern, it'll be run on a backup copy of the production db to fix any relational issues for the future. I did SELECT * FROM sys.foreign_keys but that gives me the name of the constraint - not the names of the child-parent tables and the columns in the relationship (the juicy bits). Plus the previous designer used short, non-descriptive/random names for the FK constraints, unlike our practice below The way we're adding constraints into SQL Server: ALTER TABLE [dbo].[UserEmailPrefs] WITH CHECK ADD CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] FOREIGN KEY([UserId]) REFERENCES [dbo].[UserMasterTable] ([UserId]) ON DELETE CASCADE GO ALTER TABLE [dbo].[UserEmailPrefs] CHECK CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] GO The comments in this SO question inpire this question.

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  • How can I change the default startup directory for cmd.exe?

    - by Nano HE
    Hi. My Procedure last day as below Click Start, Run and type Regedit.exe Navigate to the following branch: HKEY_CURRENT_USER \ Software \ Microsoft \ Command Processor In the right-pane, double-click Autorun and set the startup folder path as its data, preceded by “CD /d “. If Autorun value is missing, you need to create one, of type REG_EXPAND_SZ or REG_SZ in the above location. Example: To set the startup directory to D:\learning\perl, set the Autorun value data to CD /d D:\learning\perl Then I clicked Start, run and type cmd. It successfully. I could do perl practice more conveniently now. But today, I find when I try to build my Visual Studio 2005 solution which included some Pre-build event Command like this: perl.exe MyAppVersion.pl perl.exe AttrScan.pl It doesn't work. Show error: can't find the path. I check the environment variable setting and find the variable-path and it's value-c:\perl\bin\; still exist. Finially, I try to removed the Regedit.exe configuration "Autorun" value and test again. The issue fixed. I only changed the default startup directory for cmd.exe command. Why the pre-build event perl command was impacted? (I am using winxp and activePerl 5.8)

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  • What is the best way to lay out elements in GWT?

    - by KutaBeach
    What is the best practice to specify the positions of elements in GWT widget? Imagine you have a task: place a set of widgets in page layout. What would you use to position all your buttons and inputs in some order? standart HTML markup with tables/divs + CSS styles for positioning GWT widgets: panels, grids, tables + CSS styles for positioning GWT widgets: panels, grids, tables + their native properties for positioning If 2 or 3 - what would you use to reproduce a standart HTML table with colspans, fixed width columns and paddings? ps UIBinder and XML markup. GWT 2.4 My opinion: one of the biggest advantages of GWT is the ability to prevent programmer from writing HTML markup and add cross-browser support for interfaces. We shouldn't drop these points so its better to choose p.3 and try to use CSS ONLY for decoration - i.e. colors, fonts etc. Another point of view: its a bad idea to place any styles inline. By specifying properties of the widgets in XML markup we are literally doing exactly this. Also, GWT doesn't have enough widgets to produce a normal layout. For example you need to create a simple table with collspans and fixed column width. How would you go about this? Looks like you have to embed several HorizontalPanels into VerticalPanels, specify width/height in everyone of them and produce a great paper of XML by this. So whats your opinion?

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  • Asynchronous SQL Operations

    - by Paul Hatcherian
    I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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  • Catching exception in Main() method

    - by Corvin
    Consider the following simple application: a windows form created by a "new C# windows application" sequence in VS that was modified in a following way: public static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); try { Application.Run(new Form1()); } catch (Exception ex) { MessageBox.Show("An unexpected exception was caught."); } } Form1.cs contains the following modifications: private void Form1_Load(object sender, EventArgs e) { throw new Exception("Error"); } If I press F5 in IDE, then, as I expect, I see a message box saying that exception was caught and the application quits. If I go to Debug(or Release)/bin and launch the executable, I see the standard "Unhandled exception" window, meaning that my exception handler doesn't work. Obviously, that has something to do with exception being thrown from a different thread that Application.Run is called from. But the question remains - why the behavior differs depending on whether the application has been run from IDE or from command line? What is the best practice to ensure that no exceptions remain unhandled in the application?

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  • Is method reference caching a good idea in Java 8?

    - by gexicide
    Consider I have code like the following: class Foo { Y func(X x) {...} void doSomethingWithAFunc(Function<X,Y> f){...} void hotFunction(){ doSomethingWithAFunc(this::func); } } Consider that hotFunction is called very often. Would it then be advisable to cache this::func, maybe like this: class Foo { Function<X,Y> f = this::func; ... void hotFunction(){ doSomethingWithAFunc(f); } } As far as my understanding of java method references goes, the Virtual Machine creates an object of an anonymous class when a method reference is used. Thus, caching the reference would create that object only once while the first approach creates it on each function call. Is this correct? Should method references that appear at hot positions in the code be cached or is the VM able to optimize this and make the caching superfluous? Is there a general best practice about this or is this highly VM-implemenation specific whether such caching is of any use?

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  • Security strategies for storing password on disk

    - by Mike
    I am building a suite of batch jobs that require regular access to a database, running on a Solaris 10 machine. Because of (unchangable) design constraints, we are required use a certain program to connect to it. Said interface requires us to pass a plain-text password over a command line to connect to the database. This is a terrible security practice, but we are stuck with it. I am trying to make sure things are properly secured on our end. Since the processing is automated (ie, we can't prompt for a password), and I can't store anything outside the disk, I need a strategy for storing our password securely. Here are some basic rules The system has multiple users. We can assume that our permissions are properly enforced (ie, if a file with a is chmod'd to 600, it won't be publically readable) I don't mind anyone with superuser access looking at our stored password Here is what i've got so far Store password in password.txt $chmod 600 password.txt Process reads from password.txt when it's needed Buffer overwritten with zeros when it's no longer needed Although I'm sure there is a better way.

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  • Help me refactor my World Cup Challenge Script

    - by kylemac
    I am setting up a World Cup Challenge between some friends, and decided to practice my Ruby and write a small script to automate the process. The Problem: 32 World Cup qualifiers split into 4 tiers by their Fifa ranking 8 entries Each entry is assigned 1 random team per tier Winner takes all :-) I wrote something that suffices yet is admittedly brute force. But, in my attempt to improve my Ruby, I acknowlege that this code isn't the most elegant solution around - So I turn to you, the experts, to show me the way. It may be more clear to check out this gist - https://gist.github.com/91e1f1c392bed8074531 My Current (poor) solution: require 'yaml' @teams = YAML::load(File.open('teams.yaml')) @players = %w[Player1 Player2 Player3 Player4 Player5 Player6 Player7 Player8] results = Hash.new players = @players.sort_by{rand} players.each_with_index do |p, i| results[p] = Array[@teams['teir_one'][i]] end second = @players.sort_by{rand} second.each_with_index do |p, i| results[p] << @teams['teir_two'][i] end third = @players.sort_by{rand} third.each_with_index do |p, i| results[p] << @teams['teir_three'][i] end fourth = @players.sort_by{rand} fourth.each_with_index do |p, i| results[p] << @teams['teir_four'][i] end p results I am sure there is a better way to iterate through the tiers, and duplicating the @players object ( dup() or clone() maybe?) So from one Cup Fan to another, help me out.

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  • Is there a case for parameterising using Abstract classes rather than Interfaces?

    - by Chris
    I'm currently developing a component based API that is heavily stateful. The top level components implement around a dozen interfaces each. The stock top-level components therefore sit ontop of a stack of Abstract implementations which in turn contain multiple mixin implementations and implement multiple mixin interfaces. So far, so good (I hope). The problem is that the base functionality is extremely complex to implement (1,000s of lines in 5 layers of base classes) and therefore I do not wish for component writers to implement the interfaces themselves but rather to extend my base classes (where all the boiler plate code is already written). If the API therefore accepts interfaces rather than references to the Abstract implementation that I wish for component writers to extends, then I have a risk that the implementer will not perform the validation that is both required and assumed by other areas of code. Therefore, my question is, is it sometimes valid to paramerise API methods using an abstract implementation reference rather than a reference to the interface(s) that it implements? Do you have an example of a well-designed API that uses this technique or am I trying to talk myself into bad-practice?

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  • Determine asymmetric latencies in a network

    - by BeeOnRope
    Imagine you have many clustered servers, across many hosts, in a heterogeneous network environment, such that the connections between servers may have wildly varying latencies and bandwidth. You want to build a map of the connections between servers my transferring data between them. Of course, this map may become stale over time as the network topology changes - but lets ignore those complexities for now and assume the network is relatively static. Given the latencies between nodes in this host graph, calculating the bandwidth is a relative simply timing exercise. I'm having more difficulty with the latencies - however. To get round-trip time, it is a simple matter of timing a return-trip ping from the local host to a remote host - both timing events (start, stop) occur on the local host. What if I want one-way times under the assumption that the latency is not equal in both directions? Assuming that the clocks on the various hosts are not precisely synchronized (at least that their error is of the the same magnitude as the latencies involved) - how can I calculate the one-way latency? In a related question - is this asymmetric latency (where a link is quicker in direction than the other) common in practice? For what reasons/hardware configurations? Certainly I'm aware of asymmetric bandwidth scenarios, especially on last-mile consumer links such as DSL and Cable, but I'm not so sure about latency. Added: After considering the comment below, the second portion of the question is probably better off on serverfault.

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  • IList<T> vs IEnumerable<T>. What is more efficient IList<T> or IEnumerable<T>

    - by bigb
    What is more efficient way to make methods return IList<T> or IEnumerable<T>? IEnumerable<T> it is immutable collection but IList<T> mutable and contain a lot of useful methods and properties. To cast IList<T> to IEnumerable<T> it is just reference copy: IList<T> l = new List<T>(); IEnumerable<T> e = l; To cast IEnumerable<T> to List<T> we need to iterate each element or to call ToList() method: IEnumerable<T>.ToList(); or may pass IEnumerable<T> to List<T> constructor which doing the same iteration somewhere within its constructor. List<T> l = new List<T>(e); Which cases you think is more efficient? Which you prefer more in your practice?

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  • Sys. engineer has decided to dynamically transform all XSLs into DLLs on website build process. DLL

    - by John Sullivan
    Hello, OS: Win XP. Here is my situation. I have a browser based application. It is "wrapped" in a Visual Basic application. Our "Systems Engineer Senior" has decided to spawn DLL files from all of our XSL pages (many of which have duplicate names) upon building a new instance of the website and have the active server pages (ASPX) use the DLL instead. This has created a "known issue" in which ~200 DLL naming conflicts occur and, thus, half of our application is broken. I think a solution to this problem is that, thankfully, we're generating the names of the DLLs and linking them up with our application dynamically. Therefore we can do something kludgy like generate a hash and append it to the end of the DLL file name when we build our website, then always reference the DLL that had some kind of random string / hash appended to its name. Aside from outright renaming the DLLs, is there another way to have multiple DLLs with the same name register for one application? I think the answer is "No, only between different applications using a special technique." Please confirm. Another question I have on my mind is whether this whole idea is a good practice -- converting our XSL pages (which we use in mass -- every time a response from our web app occurs) into DLL functions that call a "function" to do what the XSL page did via an active server page (ASPX), when we were before just sending an XML response to an XSL page via aspx.

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  • How can I ignore the block content reading in Perl.

    - by Nano HE
    Hello. I plan to ignore the block content which include the start line of "MaterializeU4()" with the subroutin() read_block below. But failed. # Read a constant definition block from a file handle. # void return when there is no data left in the file. # Otherwise return an array ref containing lines to in the block. sub read_block { my $fh = shift; my @lines; my $block_started = 0; while( my $line = <$fh> ) { # how to correct my code below? I don't need the 2nd block content. $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 0) ) ; if( $block_started ) { last if $line =~ /^\s*$/; push @lines, $line; } } return \@lines if @lines; return; } Data as below: __DATA__ status DynTest = <dynamic 100> vid = 10002 name = "DynTest" units = "" status VIDNAME9000 = <U4 MaterializeU4()> vid = 9000 name = "VIDNAME9000" units = "degC" status DynTest = <U1 100> vid = 100 name = "Hello" units = "" Output: <StatusVariables> <SVID logicalName="DynTest" type="L" value="100" vid="10002" name="DynTest" units=""></SVID> <SVID logicalName="VIDNAME9000" type="L" value="MaterializeU4()" vid="9000" name="VIDNAME9000" units="degC"></SVID> <SVID logicalName="DynTest" type="L" value="100" vid="100" name="Hello" units=""></SVID> </StatusVariables> [Updated] I print the value of index($line, "MaterializeU4"), it output 25. Then I updated the code as below $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 25) Now it works. Any comments are welcome about my practice. Thank you.

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  • C++ STL: How to iterate vector while requiring access to element and its index?

    - by Ashwin
    I frequently find myself requiring to iterate over STL vectors. While I am doing this I require access to both the vector element and its index. I used to do this as: typedef std::vector<Foo> FooVec; typedef FooVec::iterator FooVecIter; FooVec fooVec; int index = 0; for (FooVecIter i = fooVec.begin(); i != fooVec.end(); ++i, ++index) { Foo& foo = *i; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } After discovering BOOST_FOREACH, I shortened this to: typedef std::vector<Foo> FooVec; FooVec fooVec; int index = -1; BOOST_FOREACH( Foo& foo, fooVec ) { ++index; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } Is there a better or more elegant way to iterate over STL vectors when both reference to the vector element and its index is required? I am aware of the alternative: for (int i = 0; i < fooVec.size(); ++i) But I keep reading about how it is not a good practice to iterate over STL containers like this.

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