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Creating rapid function overloads in C++

- by DeadMG

template<typename Functor, typename Return, typename Arg1, typename Arg2, typename Arg3, typename Arg4, typename Arg5, typename Arg6, typename Arg7, typename Arg8, typename Arg9, typename Arg10> class LambdaCall : public Instruction { public: LambdaCall(Functor func ,unsigned char constructorarg1 ,unsigned char constructorarg2 ,unsigned char constructorarg3 ,unsigned char constructorarg4 ,unsigned char constructorarg5 ,unsigned char constructorarg6 ,unsigned char constructorarg7 ,unsigned char constructorarg8 ,unsigned char constructorarg9 ,unsigned char constructorarg10) : arg1(constructorarg1) , arg2(constructorarg2) , arg3(constructorarg3) , arg4(constructorarg4) , arg5(constructorarg5) , arg6(constructorarg6) , arg7(constructorarg7) , arg8(constructorarg8) , arg9(constructorarg9) , arg10(constructorarg10) , function(func) {} void Call(State& state) { state.Push<Return>(func(*state.GetRegisterValue<Arg1>(arg1) ,*state.GetRegisterValue<Arg1>(arg1) ,*state.GetRegisterValue<Arg2>(arg2) ,*state.GetRegisterValue<Arg3>(arg3) ,*state.GetRegisterValue<Arg4>(arg4) ,*state.GetRegisterValue<Arg5>(arg5) ,*state.GetRegisterValue<Arg6>(arg6) ,*state.GetRegisterValue<Arg7>(arg7) ,*state.GetRegisterValue<Arg8>(arg8) ,*state.GetRegisterValue<Arg9>(arg9) ,*state.GetRegisterValue<Arg10>(arg10) )); } Functor function; unsigned char arg1; unsigned char arg2; unsigned char arg3; unsigned char arg4; unsigned char arg5; unsigned char arg6; unsigned char arg7; unsigned char arg8; unsigned char arg9; unsigned char arg10; }; Then again for every possible number of arguments I want to support, and again for void returns. Any way to do this faster?

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Sharing rails fragments between formats

- by Julian

Hi I'm toying with mobile_fu and want to share some fragments between the different views. E.g. views/ item/ view.html.erb view.mobile.rb shared/ _common.erb In both view.html.erb and view.mobile.erb I want to share the same fragment '_common.erb' without having to specify the format (should you ever have to specify the format inside a fragment? It doesn't seem like The Rails Way?). Let's say for arguments's sake it's because it's in a helper or whatever -- the point is that I need to share fragments in a 'well-defined and Railsy way' across formats. Let's take this fairly innocuous snippet <% render :fragment => 'shared/common' %> I've tried 3 file name conventions: _common.html.erb only works for html /item/view/xx fails with 'shared/_common.erb not found') however _common.erb fails for html and works for mobile (maybe mobile_fu is doing something wacky?) -- same error as for .html.erb version above _common.rhtml does work for both I'm thinking that: that rhtml works for both is a legacy hack and I'm loathe to rename all the shared fragments .rhtml to get the behaviour I want. Any feedback gratefully welcome! Including 'you fundamentally don't understand how Rails works please RTFM here: http://....' :)

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Method not being resolved for dynamic generic type

- by kelloti

I have these types: public class GenericDao<T> { public T Save(T t) { return t; } } public abstract class DomainObject { // Some properties protected abstract dynamic Dao { get; } public virtual void Save() { var dao = Dao; dao.Save(this); } } public class Attachment : DomainObject { protected dynamic Dao { get { return new GenericDao<Attachment>(); } } } Then when I run this code it fails with RuntimeBinderException: Best overloaded method match for 'GenericDAO<Attachment.Save(Attachment)' has some invalid arguments var obj = new Attachment() { /* set properties */ }; obj.Save(); I've verified that in DomainObject.Save() "this" is definitely Attachment, so the error doesn't really make sense. Can anyone shed some light on why the method isn't resolving? Some more information - It succeeds if I change the contents of DomainObject.Save() to use reflection: public virtual void Save() { var dao = Dao; var type = dao.GetType(); var save = ((Type)type).GetMethod("Save"); save.Invoke(dao, new []{this}); }

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DBD::CSV: Problem with userdefined functions

- by sid_com

From the SQL::Statement::Functions documentation: Creating User-Defined Functions ... More complex functions can make use of a number of arguments always passed to functions automatically. Functions always receive these values in @_: sub FOO { my( $self, $sth, $rowhash, @params ); } #!/usr/bin/env perl use 5.012; use warnings; use strict; use DBI; my $dbh = DBI->connect( "DBI:CSV:", undef, undef, { RaiseError => 1, } ); my $table = 'wages'; my $array_ref = [ [ 'id', 'number' ], [ 0, 6900 ], [ 1, 3200 ], [ 2, 1800 ], ]; $dbh->do( "CREATE TEMP TABLE $table AS import( ? )", {}, $array_ref ); sub routine { my $self = shift; my $sth = shift; my $rowhash = shift; # return $_[0] / 30; }; $dbh->do( "CREATE FUNCTION routine" ); my $sth = $dbh->prepare( "SELECT id, routine( number ) AS result FROM $table" ); $sth->execute(); $sth->dump_results(); When I try this I get an error-message: DBD::CSV::st execute failed: Use of uninitialized value $_[0] in division (/) at ./so.pl line 27. [for Statement "SELECT id, routine( number ) AS result FROM "wages""] at ./so.pl line 34. When I comment out the third argument I works as expected ( because it looks as if the third argument is missing ): #!/usr/bin/env perl ... sub routine { my $self = shift; my $sth = shift; #my $rowhash = shift; return $_[0] / 30; }; ... 0, 230 1, 106.667 2, 60 3 rows Is this a bug?

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Locking database edit by key name

- by Will Glass

I need to prevent simultaneous edits to a database field. Users are executing a push operation on a structured data field, so I want to sequence the operations, not simply ignore one edit and take the second. Essentially I want to do synchronized(key name) { push value onto the database field } and set up the synchronized item so that only one operation on "key name" will occur at a time. (note: I'm simplifying, it's not always a simple push). A crude way to do this would be a global synchronization, but that bottlenecks the entire app. All I need to do is sequence two simultaneous writes with the same key, which is rare but annoying occurrence. This is a web-based java app, written with Spring (and using JPA/MySQL). The operation is triggered by a user web service call. (the root cause is when a user sends two simultaneous http requests with the same key). I've glanced through the Doug Lea/Josh Bloch/et al Concurrency in Action, but don't see an obvious solution. Still, this seems simple enough I feel there must be an elegant way to do this.

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Drupal: How to Render Results of Form on Same Page as Form

- by Aaron

How would I print the results of a form submission on the same page as the form itself? Relevant hook_menu: $items['admin/content/ncbi_subsites/paths'] = array( 'title' => 'Paths', 'description' => 'Paths for a particular subsite', 'page callback' => 'ncbi_subsites_show_path_page', 'access arguments' => array( 'administer site configuration' ), 'type' => MENU_LOCAL_TASK, ); page callback: function ncbi_subsites_show_path_page() { $f = drupal_get_form('_ncbi_subsites_show_paths_form'); return $f; } Form building function: function _ncbi_subsites_show_paths_form() { // bunch of code here $form['subsite'] = array( '#title' => t('Subsites'), '#type' => 'select', '#description' => 'Choose a subsite to get its paths', '#default_value' => 'Choose a subsite', '#options'=> $tmp, ); $form['showthem'] = array( '#type' => 'submit', '#value' => 'Show paths', '#submit' => array( 'ncbi_subsites_show_paths_submit'), ); return $form; } Submit function (skipped validate function for brevity) function ncbi_subsites_show_paths_submit( &$form, &$form_state ) { //dpm ( $form_state ); $subsite_name = $form_state['values']['subsite']; $subsite = new Subsite( $subsite_name ); //y own class that I use internally in this module $paths = $subsite->normalized_paths; // build list $list = theme_item_list( $paths ); } If I print that $list variable, it is exactly what I want, but I am not sure how to get it into the page with the original form page built from 'ncbi_subsites_show_path_page'. Any help is much appreciated!

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Omit Properties from WebControl Serialization

- by Laramie

I have to serialize several objects inheriting from WebControl for database storage. These include several unecessary (to me) properties that I would prefer to omit from serialization. For example BackColor, BorderColor, etc. Here is an example of an XML serialization of one of my controls inheriting from WebControl. <Control xsi:type="SerializePanel"> <ID>grCont</ID> <Controls /> <BackColor /> <BorderColor /> <BorderWidth /> <CssClass>grActVid bwText</CssClass> <ForeColor /> <Height /> <Width /> ... </Control> I have been trying to create a common base class for my controls that inherits from WebControl and uses the "xxxSpecified" trick to selectively choose not to serialize certain properties. For example to ignore an empty BorderColor property, I'd expect [XmlIgnore] public bool BorderColorSpecified() { return !base.BorderColor.IsEmpty; } to work, but it's never called during serialization. I've also tried it in the class to be serialized as well as the base class. Since the classes themselves might change, I'd prefer not to have to create a custom serializer. Any ideas?

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Complicated .NET factory design

- by Tom W

Hello SO; I'm planning to ask a fairly elaborate question that is also something of a musing here, so bear with me... I'm trying to design a factory implementation for a simulation application. The simulation will consist of different sorts of entities i.e. it is not a homogenous simulation in any respect. As a result, there will be numerous very different concrete implementations and only the very general properties will be abstracted at the top level. What I'd like to be able to do is create new simulation entities by calling a method on the model with a series of named arguments representing the parameters of the entity, and have the model infer what type of object is being described by the inbound parameters (from the names of the parameters and potentially the sequence they occur in) and call a factory method on the appropriate derived class. For example, if I pass the model a pair of parameters (Param1=5000, Param2="Bacon") I would like it to infer that the names Param1 and Param2 'belong' to the class "Blob1" and call a shared function "getBlob1" with named parameters Param1:=5000, Param2:="Bacon" whereas if I pass the model (Param1=5000, Param3=50) it would call a similar factory method for Blob2; because Param1 and Param3 in that order 'belong' to Blob2. I foresee several issues to resolve: Whether or not I can reflect on the available types with string parameter names and how to do this if it's possible Whether or not there's a neat way of doing the appropriate constructor inference from the combinatoric properties of the argument list or whether I'm going to have to bodge something to do it 'by hand'. If possible I'd like the model class to be able to accept parameters as parameters rather than as some collection of keys and values, which would require the model to expose a large number of parametrised methods at runtime without me having to code them explicitly - presumably one for every factory method available in the relevant namespace. What I'm really asking is how you'd go about implementing such a system, rather than whether or not it's fundamentally possible. I don't have the foresight or experience with .NET reflection to be able to figure out a way by myself. Hopefully this will prove an informative discussion.

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PNG Textures not loading on HTC desire

- by Matthew Tatum

Hi I'm developing a game for android using OpenGL es and have hit a problem: My game loads fine in the emulator (windows xp and vista from eclipse), it also loads fine on a T-Mobile G2 (HTC Hero) however when I load it on my new HTC Desire none of the textures appear to load correctly (or at all). I'm suspecting the BitmapFactory.decode method although I have no evidence that that is the problem. All of my textures are power of 2 and JPG textures seem to load (although they don't look great quality) but anything that is GIF or PNG just doesn't load at all except for a 2x2 red square which loads fine and one texture that maps to a 3d object but seems to fill each triangle of the mesh with the nearest colour). This is my code for loading images: AssetManager am = androidContext.getAssets(); BufferedInputStream is = null; try { is = new BufferedInputStream(am.open(fileName)); Bitmap bitmap; bitmap = BitmapFactory.decodeStream(is); GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); bitmap.recycle(); } catch(IOException e) { Logger.global.log(Level.SEVERE, e.getLocalizedMessage()); } finally { try { is.close(); } catch(Exception e) { // Ignore. } } thanks

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IE8 ignores jQuery UI 'dialog' minHeight and height settings

- by Kev

I'm using jQuery 1.4.4 with jQueryUI 1.8.7 to display a modal dialog box. I'm having a problem where IE8 renders a scrollbar and appears to ignore the minHeight and height options in all the many different combinations I've tried them in. In Chrome 8 and Firefox 3.6 my dialogue looks like: In IE 8 it looks like: The markup and script looks like: <a id="create" href="#">Create New Thing</a> <div id="dlg-create-thing" title="Create new thing?"> <form name="create-thing-form" id="dlg-create-thing-form"> <p style="text-align:left"> <span>Name: <input id="thingName" name="thingName" maxlength="12" size="30" /></span> <br /><br /> <b>Thing options:</b><br /><br /> <input type="radio" id="option1" name="theoptions" value="0" checked="checked" />Use this option<br /> <input type="radio" id="option1AndMem" name="theoptions" value="1" />Use this other option </p> </form> </div> <script type="text/javascript"> $(function () { $("#dlg-create-thing").dialog({ autoOpen: false, resizable: false, width: 500, modal: true, minHeight: 280, buttons: { "Create": function () { /* do stuff */ }, "Cancel": function () { /* do other stuff */} } }); $("body").delegate("a[id='create']", "click", function () { $("#dlg-create-thing").dialog('open'); return false; } ); }); </script> How can I fix this (preferably in a nice browser agnostic way, but I'd settle for anything)?

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Compile time error: cannot convert from specific type to a generic type

- by Water Cooler v2

I get a compile time error with the following relevant code snippet at the line that calls NotifyObservers in the if construct. public class ExternalSystem<TEmployee, TEventArgs> : ISubject<TEventArgs> where TEmployee : Employee where TEventArgs : EmployeeEventArgs { protected List<IObserver<TEventArgs>> _observers = null; protected List<TEmployee> _employees = null; public virtual void AddNewEmployee(TEmployee employee) { if (_employees.Contains(employee) == false) { _employees.Add(employee); string message = FormatMessage("New {0} hired.", employee); if (employee is Executive) NotifyObservers(new ExecutiveEventArgs { e = employee, msg = message }); else if (employee is BuildingSecurity) NotifyObservers(new BuildingSecurityEventArgs { e = employee, msg = message }); } } public void NotifyObservers(TEventArgs args) { foreach (IObserver<TEventArgs> observer in _observers) observer.EmployeeEventHandler(this, args); } } The error I receive is: The best overloaded method match for 'ExternalSystem.NotifyObservers(TEventArgs)' has some invalid arguments. Cannot convert from 'ExecutiveEventArgs' to 'TEventArgs'. I am compiling this in C# 3.0 using Visual Studio 2008 Express Edition.

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do not allow integrated windows authentication *for one of the domains*

- by MK

We have an ASP.NET web application which uses integrated windows authentication. It is accessed by users from two domains, A and B. A is the primary domain and B is an older domain which is going away. Web application is authenticating users using a group policy which only exists in domain A. Every user in domain B has an account in domain A. The application lives in domain A. There was no trust between the domains. So users from domain A would get silently authenticated and logged into the site. Users from domain B didn't get authenticated automatically and were prompted with the IE popup, to which they authenticated using their domain A credentials and everything worked. Now somebody has set up a trust between the domains and users from domain B get authenticated silently to IIS, and then their login fails (no group policy). So the question is: can I either programmatically or in IIS configuration make it so that users from domain B still get prompted even though there is trust between the domains? Is there a way to tell the server where IIS is running to ignore the trust relationship maybe?

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How to detect the root recursive call?

- by ahmadabdolkader

Say we're writing a simple recursive function fib(n) that calculates the nth Fibonacci number. Now, we want the function to print that nth number. As the same function is being called repeatedly, there has to be a condition that allows only the root call to print. The question is: how to write this condition without passing any additional arguments, or using global/static variables. So, we're dealing with something like this: int fib(int n) { if(n <= 0) return 0; int fn = 1; if(n > 2) fn = fib(n-2) + fib(n-1); if(???) cout << fn << endl; return fn; } int main() { fib(5); return 0; } I thought that the root call differs from all children by returning to a different caller, namely the main method in this example. I wanted to know whether it is possible to use this property to write the condition and how. Update: please note that this is a contrived example that only serves to present the idea. This should be clear from the tags. I'm not looking for standard solutions. Thanks.

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Indexing table with duplicates MySQL/MSSQL with millions of records

- by Tesnep

I need help in indexing in MySQL. I have a table in MySQL with following rows: ID Store_ID Feature_ID Order_ID Viewed_Date Deal_ID IsTrial The ID is auto generated. Store_ID goes from 1 - 8. Feature_ID from 1 - let's say 100. Viewed Date is Date and time on which the data is inserted. IsTrial is either 0 or 1. You can ignore Order_ID and Deal_ID from this discussion. There are millions of data in the table and we have a reporting backend that needs to view the number of views in a certain period or overall where trial is 0 for a particular store id and for a particular feature. The query takes the form of: select count(viewed_date) from theTable where viewed_date between '2009-12-01' and '2010-12-31' and store_id = '2' and feature_id = '12' and Istrial = 0 In MSSQL you can have a filtered index to use for Istrial. Is there anything similar to this in MySQL? Also, Store_ID and Feature_ID have a lot of duplicate data. I created an index using Store_ID and Feature_ID. Although this seems to have decreased the search period, I need better improvement than this. Right now I have more than 4 million rows. To search for a particular query like the one above, it looks at 3.5 million rows in order to give me the count of 500k rows. PS. I forgot to add view_date filter in the query. Now I have done this.

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VS2008 Link Error Using SafeInt3.hpp in 64bit mode.

- by photo_tom

I have the below code that links and runs fine in 32bit mode - #include "safeint3.hpp" typedef SafeInt<SIZE_T> SAFE_SIZE_T; SAFE_SIZE_T sizeOfCache; SAFE_SIZE_T _allocateAmt; Where safeint3.hpp is current version that can be found on Codeplex SafeInt. For those who are unaware of it, safeint is a template class that makes working with different integer types and sizes "safe". To quote channel 9 video on software - "it writes the code that you should". Which is my case. I have a class that is managing a large in-memory cache of objects (6gb) and I am very concerned about making sure that I don't have overflow/underflow issues on my pointers/sizes/other integer variables. In this use, it solves many problems. My problem is coming when moving from 32bit dev mode to 64bit production mode. When I build the app in this mode, I'm getting the following linker warnings - 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyUint64(unsigned __int64 const &,unsigned __int64 const &,unsigned __int64 *)" (?IntrinsicMultiplyUint64@@YA_NAEB_K0PEA_K@Z) already defined in ImageInRamCache.obj; second definition ignored 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyInt64(__int64 const &,__int64 const &,__int64 *)" (?IntrinsicMultiplyInt64@@YA_NAEB_J0PEA_J@Z) already defined in ImageInRamCache.obj; second definition ignored While I understand I can ignore the error, I would like either (a) prevent the warning from occurring or (b) make it disappear so that my QA department doesn't flag it as a problem. And after spending some time researching it, I cannot find a way to do either.

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Change Sequence to Choice

- by Gordon

In my Schema File I defined a Group with a Sequence of possible Elements. <group name="argumentGroup"> <sequence> <element name="foo" type="double" /> <element name="bar" type="string" /> <element name="baz" type="integer" /> </sequence> </group> I then reference this Group like this: <element name="arguments"> <complexType> <group ref="my:argumentGroup"/> </complexType> </element> Is it possible to reference the Group at some other point but restrict it so it's a Choice instead of a Sequence. The position where I want to reuse it would only allow one of the Elements within. <element name="argument" minOccurs="0" maxOccurs="1"> <complexType> <group name="my:argumentGroup"> <! -- Somehow change argumentGroup sequence to choice here --> </group> <complexType> </element>

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Getting memory leak at NSURL connection in Iphone sdk.

- by monish

Hi guys, Here Im getting leak at the NSURL connection in my libxml parser can anyone tell how to resolve it. The code where leak generates is: - (BOOL)parseWithLibXML2Parser { BOOL success = NO; ZohoAppDelegate *appDelegate = (ZohoAppDelegate*) [ [UIApplication sharedApplication] delegate]; NSString* curl; if ([cName length] == 0) { curl = @"https://invoice.zoho.com/api/view/settings/currencies?ticket="; curl = [curl stringByAppendingString:appDelegate.ticket]; curl = [curl stringByAppendingString:@"&apikey="]; curl = [curl stringByAppendingString:appDelegate.apiKey]; curl = [curl stringByReplacingOccurrencesOfString:@"\n" withString:@""]; } NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:curl]]; NSLog(@"the request parserWithLibXml2Parser %@",theRequest); NSURLConnection *con = [[[NSURLConnection alloc] initWithRequest:theRequest delegate:self] autorelease];//Memory leak generated here at this line of code. //self.connection = con; //[con release]; // This creates a context for "push" parsing in which chunks of data that are // not "well balanced" can be passed to the context for streaming parsing. // The handler structure defined above will be used for all the parsing. The // second argument, self, will be passed as user data to each of the SAX // handlers. The last three arguments are left blank to avoid creating a tree // in memory. _xmlParserContext = xmlCreatePushParserCtxt(&simpleSAXHandlerStruct, self, NULL, 0, NULL); if(con != nil) { do { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } while (!_done && !self.error); } if(self.error) { //NSLog(@"parsing error"); [self.delegate parser:self encounteredError:nil]; } else { success = YES; } return success; } Anyone's help will be muck appreciated . Thank you, Monish.

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How can I handle all my errors/messages in one place on an Asp.Net page?

- by Atomiton

Hi all, I'm looking for some guidance here. On my site I put things in Web user controls. For example, I will have a NewsItem Control, an Article Control, a ContactForm control. These will appear in various places on my site. What I'm looking for is a way for these controls to pass messages up to the Page that they exist on. I don't want to tightly couple them, so I think I will have to do this with Events/Delegates. I'm a little unclear as to how I would implement this, though. A couple of examples: 1 A contact form is submitted. After it's submitted, instead of replacing itself with a "Your mail has been sent" which limits the placement of that message, I'd like to just notify the page that the control is on with a Status message and perhaps a suggested behaviour. So, a message would include the text to render as well as an enum like DisplayAs.Popup or DisplayAs.Success 2 An Article Control queries the database for an Article object. Database returns an Exception. Custom Exception is passed to the page along with the DisplayAs.Error enum. The page handles this error and displays it wherever the errors go. I'm trying to accomplish something similar to the ValidationSummary Control, except that I want the page to be able to display the messages as the enum feels fit. Again, I don't want to tightly bind or rely a control existing on the Page. I want the controls to raise these events, but the page can ignore them if it wants. Am I going about this the right way? I'd love a code sample just to get me started. I know this is a more involved question, so I'll wait longer before voting/choosing the answers.

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Java: refactoring static constants

- by akf

We are in the process of refactoring some code. There is a feature that we have developed in one project that we would like to now use in other projects. We are extracting the foundation of this feature and making it a full-fledged project which can then be imported by its current project and others. This effort has been relatively straight-forward but we have one headache. When the framework in question was originally developed, we chose to keep a variety of constant values defined as static fields in a single class. Over time this list of static members grew. The class is used in very many places in our code. In our current refactoring, we will be elevating some of the members of this class to our new framework, but leaving others in place. Our headache is in extracting the foundation members of this class to be used in our new project, and more specifically, how we should address those extracted members in our existing code. We know that we can have our existing Constants class subclass this new project's Constants class and it would inherit all of the parent's static members. This would allow us to effect the change without touching the code that uses these members to change the class name on the static reference. However, the tight coupling inherent in this choice doesn't feel right. before: public class ConstantsA { public static final String CONSTANT1 = "constant.1"; public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } after: public class ConstantsA extends ConstantsB { public static final String CONSTANT1 = "constant.1"; } public class ConstantsB { public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } In our existing code branch, all of the above would be accessible in this manner: ConstantsA.CONSTANT2 I would like to solicit arguments about whether this is 'acceptable' and/or what the best practices are.

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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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Error when feeding a mysql db with a python-parsed data

- by Barnabe

I use this bit of code to feed some data i have parsed from a web page to a mysql database c=db.cursor() c.executemany( """INSERT INTO data (SID, Time, Value1, Level1, Value2, Level2, Value3, Level3, Value4, Level4, Value5, Level5, ObsDate) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)""", clean_data ) The parsed data looks like this (there are several hundred such lines) clean_data = [(161,00:00:00,8.19,1,4.46,4,7.87,4,6.54,null,4.45,6,2010-04-12),(162,00:00:00,7.55,1,9.52,1,1.90,1,4.76,null,0.14,1,2010-04-12),(164,00:00:00,8.01,1,8.09,1,0,null,8.49,null,0.20,2,2010-04-12),(166,00:00:00,8.30,1,4.77,4,10.99,5,9.11,null,0.36,2,2010-04-12)] if i hard code the data as above mySQL accepts my request (except for some quibbles about formatting) but if the variable clean_data is instead defined as the result of the parsing code, like this: cleaner = [(""" $!!'""", ')]'),(' $!!', ') etc etc] def processThis(str,lst): for find, replace in lst: str = str.replace(find, replace) return str clean_data = processThis(data,cleaner) then i get the dreaded "TypeError: not enough arguments for format string" After playing with formatting options for a few hours (I am very new to this) I am confused... what is the difference between the hard coded data and the result of the processThis function as fas as mySQL is concerned? Any idea greatly appreciated...

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What kind of data do I pass into a Django Model.save() method?

- by poswald

Lets say that we are getting POSTed a form like this in Django: rate=10 items= [23,12,31,52,83,34] The items are primary keys of an Item model. I have a bunch of business logic that will run and create more items based on this data, the results of some db lookups, and some business logic. I want to put that logic into a save signal or an overridden Model.save() method of another model (let's call it Inventory). The business logic will run when I create a new Inventory object using this form data. Inventory will look like this: class Inventory(models.Model): picked_items = models.ManyToManyField(Item, related_name="items_picked_set") calculated_items = models.ManyToManyField(Item, related_name="items_calculated_set") rate = models.DecimalField() ... other fields here ... New calculated_items will be created based on the passed in items which will be stored as picked_items. My question is this: is it better for the save() method on this model to accept: the request object (I don't really like this coupling) the form data as arguments or kwargs (a list of primary keys and the other form fields) a list of Items (The caller form or view will lookup the list of Items and create a list as well as pass in the other form fields) some other approach? I know this is a bit subjective, but I was wondering what the general idea is. I've looked through a lot of code but I'm having a hard time finding a pattern I like.

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Why C++ is (one of) the best language to learn at first [closed]

- by AlexV

C++ is one of the most used programming language in the world since like 25+ years. My first job as programmer was in C++ and I coded in C++ everyday for nearly 4 years. Now I do mostly PHP, but I will forever cherish this C++ background. C++ has helped me understand many "under the hood" features/behaviors/restrictions of many other (and different) programming languages like PHP and Delphi. I'm a full time programmer for 6+ years now and since I have a quite varied programming background I often get questions by "newbies" as where to start to become a "good" programmer. I think C++ is one of the best language to start with because it gives you a real usefull experience that will last and will teach you how things work under the hood. It's not the easier one to learn for a newbie, but in my opinion it's the one who will reward the most in long term. I would like to know your opinion on this matter to add to my arguments when I guide "newbies". After this introduction, here's my question : Why C++ is for you (one of) the best language to learn at first. Since it's subjective, I've marked this question as community wiki.

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Regular Expressions .NET

- by Fosa

I need a regular expression for some arguments that must match on a string. here it is... The string exists out of minimum 8 en maximum 20 characters. These characters of this string may be characters of the alfabet or special chars --With other words..all charachters except from the whitespaces In the complete string there must be atleast 1 number. The string cannot start with a number or an underscore The last 2 characters of the string must be identical, But it doenst matter if those last --identical characters are capital or non-capital (case insensitive) Must match all : +234567899 a_1de*Gg xy1Me*__ !41deF_hij2lMnopq3ss C234567890123$^67800 *5555555 sDF564zer"" !!!!!!!!!4!!!!!!!!!! abcdefghijklmnopq9ss May not match : Cannot be less then 8 or more then 20 chars: a_1+Eff B41def_hIJ2lmnopq3stt Cannot contain a whitespace: A_4 e*gg b41def_Hij2l nopq3ss Cannot start with a number or an underscore: __1+Eff 841DEf_hij2lmnopq3stt cannot end on 2 diffrent characters: a_1+eFg b41DEf_hij2lmnopq3st Cannot be without a number in the string: abCDefghijklmnopqrss abcdef+++dF !!!!!!!!!!!!!!!!!!!! ------------------------------------------------------ This is what I have so far...But I'm really breaking my head on this... If you Don't know the answer completely it's not a problem... I just want to get in the right direction ([^0-9_])(?=.*\d)(\S{8,20})(?i:[\S])\1

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Detecting well behaved / well known bots

- by Simon_Weaver

I found this question very interesting : Programmatic Bot Detection I have a very similar question, but I'm not bothered about 'badly behaved bots'. I am tracking (in addition to google analytics) the following per visit : Entry URL Referer UserAgent Adwords (by means of query string) Whether or not the user made a purchase etc. The problem is that to calculate any kind of conversion rate I'm ending up with lots of 'bot' visits that are greatly skewing my results. I'd like to ignore as many as possible bot visits, but I want a solution that I don't need to monitor too closely, and that won't in itself be a performance hog and preferably still work if someone has javascript disabled. Are there good published lists of the top 100 bots or so? I did find a list at http://www.user-agents.org/ but that appears to contain hundreds if not thousands of bots. I don't want to check every referer against thousands of links. Here is the current googlebot UserAgent. How often does it change? Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

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