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• Performance of Managed C++ Vs UnManaged/native C++

  - by bsobaid

  I am writing a very high performance application that handles and processes hundreds of events every millisecond. Is Unmanaged C++ faster than managed c++? and why? Managed C++ deals with CLR instead of OS and CLR takes care of memory management, which simplifies the code and is probably also more efficient than code written by "a programmer" in unmanaged C++? or there is some other reason? When using managed, how can one then avoid dynamic memory allocation, which causes a performance hit, if it is all transparent to the programmer and handled by CLR? So coming back to my question, Is managed C++ more efficient in terms of speed than unmanaged C++ and why?

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• Maintaining sort order of database table rows

  - by Lox

  Say I have at database table containing information about a news article in each row. The table has an integer "sort" column to dictate the order in which the articles are to be presented on a web site. How do I best implement and maintain this sort order. The problem I want to avoid is having the the articles numbered 1,2,3,4,..,100 and when article number 50 suddenly becomes interesting it gets its sort number set to 1 and then all articles between them must have their sort number increased by one. Sure, setting initial sort numbers to 100,200,300,400 etc. leaves some space for moving around but at some point it will break. Is there a correct way to do this, maybe a completely different approach? Added-1: All article titles are shown in a list linking to the contents, so yes all sorted items are show at once. Added-2: An item is not necessarily moved to the top of the list; any item can be placed anywhere in the ordered list.

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• Creating a unique key based on file content in python

  - by Cawas

  I got many, many files to be uploaded to the server, and I just want a way to avoid duplicates. Thus, generating a unique and small key value from a big string seemed something that a checksum was intended to do, and hashing seemed like the evolution of that. So I was going to use hash md5 to do this. But then I read somewhere that "MD5 are not meant to be unique keys" and I thought that's really weird. What's the right way of doing this? edit: by the way, I took two sources to get to the following, which is how I'm currently doing it and it's working just fine, with Python 2.5: import hashlib def md5_from_file (fileName, block_size=2**14): md5 = hashlib.md5() f = open(fileName) while True: data = f.read(block_size) if not data: break md5.update(data) f.close() return md5.hexdigest()

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• Using Report (Reporting Services) parameter values in ASP.NET page

  - by noup

  I have a report (Reporting Services) integrated into an ASP.NET that shows dropdownlists to select report parameter values. The dropdownlists are populated using direct database selects, though I see the report RDL files do contain the paramter values and datasets as defined in the report designer. Is it possible to obtain the report parameters "available values" in ASP.NET to populate the dropdownlists? This would avoid some code duplication. Update If the parameter doesn't use a query for available values, the following works: foreach (ValidValue value in this.ReportViewerControl.ServerReport.GetParameters()["myParameter"].ValidValues) { this.DropDownListControl.Items.Add(new ListItem(value.Label, value.Value)); } Still haven't found a way to access report datasets though...

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• Should I use curly brackets or concatenate variables within strings?

  - by mririgo

  Straight forward question: Is there an advantage or disadvantage to concatenating variables within strings or using curly braces instead? Concatenated: $greeting = "Welcome, ".$name."!"; Curly braces: $greeting = "Welcome, {$name}!"; Personally, I've always concatenated my strings because I use UEStudio and it highlights PHP variables a different color when concatenated. However, when the variable is not broken out, it does not. It just makes it easier for my eyes to find PHP variables in long strings, etc. EDIT: People are confusing this about being about SQL. This is not what this question is about. I've updated my examples to avoid confusion.

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• Getting the location in Android programatically

  - by steveo225

  I know this has been asked a ton, so my apologies. I have the following code, and cannot get the location, always a null response. I am trying to avoid a LocationListener in this instance because I am already using an update Service, and the location really doesn't have to be that fine, so the last known location is good enough. Thanks for the help. LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); String providers[] = {"gps", "network", "passive"}; Location loc = null; for(String x : providers) { loc = lm.getLastKnownLocation(x); if(loc != null) break; } if(loc != null) { // do something, never reached }

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• Software protection

  - by anfono

  I want to protect my software from being used without permission. I will provide it for free to the parties I authorize to use it. Anyone knows a good protection scheme against having it copied and run by unauthorized parties ? So far, I thought about introducing a key validation mechanism: periodically, the user needs to send me (web site query) a code based on which I generate a new code that app validates against. There is an initial code, and so I can track users... Thoughts ? Later edit: I changed the licensing part to avoid unfocused discussion.

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• Can I Import an updated structure into a MySQL table without losing its current content?

  - by Udi Wertheimer

  We use MySQL tables to which we add new fields from time to time as our product evolves. I'm looking for a way to export the structure of the table from one copy of the db, to another, without erasing the contents of the table I'm importing to. For example say I have copies A and B of a table, and I add fields X,Y,Z to table A. Is there a way to copy the changed structure (fields X,Y,Z) to table B while keeping its content intact? I tried to use mysqldump, but it seems I can only copy the whole table with its content, overriding the old one, or I can use the "-d" flag to avoid copying data (dumping structure only), but this will create an empty table when imported, again overriding old data. Is there any way to do what I need with mysqldump, or some other tool?

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• What are unused/undeclared dependencies in maven ? What to do with them ?

  - by b7kich

  Maven dependency:analyze complains about the dependencies in my project. How does it determine which are unused and which are undeclared ? What should I do about them ? Example: $ mvn dependency:analyze ... [WARNING] Used undeclared dependencies found: [WARNING] org.slf4j:slf4j-api:jar:1.5.0:provided [WARNING] commons-logging:commons-logging:jar:1.1.1:compile [WARNING] commons-dbutils:commons-dbutils:jar:1.1-osgi:provided [WARNING] org.codehaus.jackson:jackson-core-asl:jar:1.6.1:compile ... [WARNING] Unused declared dependencies found: [WARNING] commons-cli:commons-cli:jar:1.0:compile [WARNING] org.mortbay.jetty:servlet-api:jar:2.5-20081211:test [WARNING] org.apache.httpcomponents:httpclient:jar:4.0-alpha4:compile [WARNING] commons-collections:commons-collections:jar:3.2:provided [WARNING] javax.mail:mail:jar:1.4:provided Note: A lot of these dependencies are used in my runtime container and I declared them as provided to avoid having same library on the classpath twice with different versions.

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• Store return value of function in reference C++

  - by Ruud v A

  Is it valid to store the return value of an object in a reference? class A { ... }; A myFunction() { A myObject; return A; } //myObject goes out of scope here void mySecondFunction() { A& mySecondObject = myFunction(); } Is it possible to do this in order to avoid copying myObject to mySecondObject? myObject is not needed anymore and should be exactly the same as mySecondObject so it would in theory be faster just to pass ownership of the object from one object to another. (This is also possible using boost shared pointer but that has the overhead of the shared pointer.) Thanks in advance.

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• Could not see memory being released on closing MFC modal dialog that hosts wpf user control using HW

  - by Naveen Chiluka

  This is in continuation with my last question posted "Continuous Memory leak while using WpfHWndSource" I have to load an WPF User Control in an MFC Modal Dialog that is being invoked from the ocx control. For this I have created a MFC Regular Dll(Mixed Mode Regular dll with clr option enabled), I have created a modal dialog which will host wpf user control using HWndSource. This exported dialog is placed as a child Dialog of the above MFC dialog that is being invoked from the ocx. Ny intermediate dialog uses C++/Cli code. When the main MFC dialog is closed, I am deleteing the ptr reference of the intermediate dialog created on the heap. In the the dipose of the .Net User Control, I have set most of the references that I have created to null, unsubscribed to the events (to avoid weak refernces), unbinded from the propertes(by using clear binding). Called delete on the HwndSource and the user control(which basically calls the dispose method). But I do not see complete memory being released. Any help would be greatful.

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• What could be adding "Pragma:no-cache" to my response Headers? (Apache, PHP)

  - by Daniel Magliola

  I have a website whose maintenance I've inherited, which is a big hairy mess. One of the things i'm doing is improving performance. Among other things, I'm adding Expires headers to images. Now, there are some images that are served through a PHP file, and I notice that they do have the Expires header, but they also get loaded every time. Looking at Response Headers, I see this: Expires Wed, 15 Jun 2011 18:11:55 GMT Cache-Control no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma no-cache Which obviously explains the problem. Now, i've looked all over the code base, and it doesn't say "pragma" anywhere. .htaccess doesn't seem to have anything related either. Any ideas who could be setting those "pragma" (and "cache-control") headers, and how I can avoid it? Thanks! Daniel

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• When to pass by value?

  - by Dervin Thunk

  Dear all. I was wondering if there are examples of situations where you would purposefully pass an argument by value in C. Let me rephrase. When do you purposefully use C's pass-by-value for large objects? Or, when do you care that the object argument is fully copied in a local variable? EDIT: Now that I think about it, if you can avoid pointers, then do. Nowadays, "deep" copying is possible for mostly everything in small apps, and shallow copying is more prone to pointer bugs. Maybe.

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• Batch backup a harddrive without modifying access times C#

  - by johnathan-doena

  I'm trying to write a simple program that will backup my flash drive. I want it to work automatically and silently in the background, and I also want it to be as quick as possible. The thing is, resetting all the access times is useless to me, and something I want to avoid. I know I can read the access times and set them back, but I bet it will fail one day in the future. It would be much simpler to read the files without ever changing it. Also, what is the fastest way to do this? What differences would there be between, say, a flash drive and an external hard drive. I am writing this in C#, as it is the simplest way to do it and it will probably last more generations of Windows..

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• How to stop GHC from generating intermediate files?

  - by unknown

  When compiling a haskell source file via ghc --make foo.hs GHC always leaves behind a variety of intermediate files other than foo.exe. These are foo.hi and foo.o. I often end up having to delete the .hi and .o files to avoid cluttering up the folders. Is there a command line option for GHC not to leave behind its intermediate files? (When asked on #haskell, the best answer I got was ghc --make foo.hs && rm foo.hi foo.o.

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• How to specify a different column for a @Inheritance JPA annotation

  - by Cue

  @Entity @Inheritance(strategy = InheritanceType.JOINED) public class Foo @Entity @Inheritance(strategy = InheritanceType.JOINED) public class BarFoo extends Foo mysql> desc foo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ mysql> desc barfoo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | | foo_id | int | | bar_id | int | +---------------+-------------+ mysql> desc bar; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ Is it possible to specify column barfo.foo_id as the joined column? Are you allowed to specify barfoo.id as BarFoo's @Id since you are overriding the getter/seeter of class Foo? I understand the schematics behind this relationship (or at least I think I do) and I'm ok with them. The reason I want an explicit id field for BarFoo is exactly because I want to avoid using a joined key (foo _id, bar _id) when querying for BarFoo(s) or when used in a "stronger" constraint. (as Ruben put it)

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• Scoping in embedded groovy scripts

  - by Aaron Digulla

  In my app, I use Groovy as a scripting language. To make things easier for my customers, I have a global scope where I define helper classes and constants. Currently, I need to run the script (which builds the global scope) every time a user script is executed: context = setupGroovy(); runScript( context, "global.groovy" ); // Can I avoid doing this step every time? runScript( context, "user.groovy" ); Is there a way to setup this global scope once and just tell the embedded script interpreter: "Look here if you can't find a variable"? That way, I could run the global script once. Note: Security is not an issue here but if you know a way to make sure the user can't modify the global scope, that's an additional plus.

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• XPath filter not empty attribute

  - by Marcos Buarque

  Hi, I need to filter a XPath expression to grab only a certain attribute as not empty. I tried this: <xsl:template match="DocumentElement/QueryResults[string(@FileName)]"> and this: <xsl:template match="DocumentElement/QueryResults[string-length(@FileName)>0]"> but it did not work. I need the same kind of data returning from the folloing XPath expression... <xsl:template match="DocumentElement/QueryResults"> ... but filtered to avoid items with empty attribute @FileName. Thanks!

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• Changing ylim (axis limits) drops data falling outside range. How can this be prevented?

  - by Alex Holcombe

  df <- data.frame(age=c(10,10,20,20,25,25,25),veg=c(0,1,0,1,1,0,1)) g=ggplot(data=df,aes(x=age,y=veg)) g=g+stat_summary(fun.y=mean,geom="point") Points reflect mean of veg at each age, which is what I expected and want to preserve after changing axis limits with the command below. g=g+ylim(0.2,1) Changing axis limits with the above command unfortunately causes veg==0 subset to be dropped from the data, yielding "Warning message: Removed 4 rows containing missing values (stat_summary)" This is bad because now the data plot (stat_summary mean) omits the veg==0 points. How can this be prevented? I simply want to avoid showing the empty part of the plot- the ordinate from 0 to .2, but not drop the associated data from the stat_summary calculation.

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• Creating a Java platform game as easily as possible

  - by directx

  I need to create a Java-based platformer game for a high school project (not computer science related), and I want to spend as little time on technical stuff as possible. I'm already experienced in Java, and I already have most of the gameplay, graphics, etc. All I need to do is code it. I've looked and I'm considering one of two options that do not involving coding a game from scratch: Copy an existing Java platformer (best option, but I can't find an open source Java platformer) Use a Java game engine to avoid coding from scratch. I've looked at JGame but I'm not sure if it's the best bet for a platformer.

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• What to keep in mind when creating your own custom web services API?

  - by John Conde

  I have created a website which allows users to sign up for, and use, an online service. To help promote the website we will be have resellers who will be offering their own branded services through us. The initial plan is to allow resellers to place registration, login, and lost password forms on their own website and use an API created by us to handle these requests. I have begun outlining how I expect the API to work (and starting documenting it as well) and I want to make sure I get it right, or as close to right, as I can from the beginning as I know once you have declared a public API you want to avoid changing that API at all costs. So far I have decided: To have the user pass their account credentials with each request To require SSL for all requests What else should I be keeping in mind?

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• Why is there so much poorly indented code out there?

  - by dsimcha

  The more I browse the code to open source projects in languages that aren't Python, the more I realize that it seems a lot of programmers don't believe in proper indentation. (I won't mention any projects specifically to avoid having anyone take this question too personally.) Usually code is indented, but in a way just different enough from the standard style that it drives me crazy, especially in old/crufty code. I've noticed that when I write in C-like languages, I tend to indent correctly as religiously as when I'm writing in Python, with the exception of debugging code that I actually want to stick out like a sore thumb. Given how easy it is with a modern IDE to fix incorrect indentation, what are some rationales for not religiously keeping indentation in sync with braces?

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• How to use Map element as text of a JComboBox

  - by llm

  I am populating a JComboBox (using addItem()) with all the elements of a collection. Each element in the collection is a HashMap (so its a ComboBox of Hashmaps..). My question is - Given that I need each item to be a HashMap how do I set the text to apear in the combobox on the GUI? It needs to be the value of a certain key in the map. Normally if I am populating a combobox with my own type, I would just overide the toString() method...but I am not sure how to acheive this since I am using a Java HashMap. Any ideas (if possible, without implementing my own HashMap)? Update: It seems like there isn't anyway to avoid having the object int the JComboBox overide toString() if I want custom functionality..I wish there was a way to (1) specify the objects to be loaded into the JComboBox and (2) specify how these objects are to appear in the GUI.

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• sqlplus remove \r \n \t from spool

  - by Tom

  Hi all, Is there any sql*plus command to remove \r \n and\t from the result set that's going out to the spool file? That is, "trim" every record? We've used set trim on in the past, but it doesn't seem to bue what we need right now. I'm trying to avoid calling oracle's translate, chr functions in the sql query. For example, If my query returns this |DATA| |\n \t\t\t\t\t thisistheactualdata \t\t\t\t\t\t\n| I'd like to keep this |DATA| |thisistheactualdata| Thanks in advance.

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• Applying styles for custom TextArea in ActionScript 3

  - by Vijay Dev

  I have the following code to create and apply a few styles for a custom TextArea in ActionScript 3. public class MyCustomTextArea extends TextArea { override protected function createChildren():void { super.createChildren(); this.styleSheet.setStyle("sup", { display: "inline", fontFamily: "ArialSup", fontSize:"12"}); this.styleSheet.setStyle("sub", { display: "inline", fontFamily: "ArialSub", fontSize:"12"}); this.setStyle("fontFamily", "Arial"); } } I have two problems with this code. this.styleSheet is always null when I create an instance of the class. If this.styleSheet is initialized to new StyleSheet() to avoid this issue, then the TextArea instance does not seem to recognize any of the HTML tags that can be used with the htmlText property. Can anyone help in fixing these two issues? Thanks.

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