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• Your favourite C++ Standard Library wrapper functions?

  - by Neil Butterworth

  This question, asked this morning, made me wonder which features you think are missing from the C++ Standard Library, and how you have gone about filling the gaps with wrapper functions. For example, my own utility library has this function for vector append: template <class T> std::vector<T> & operator += ( std::vector<T> & v1, const std::vector <T> v2 ) { v1.insert( v1.end(), v2.begin(), v2.end() ); return v1; } and this one for clearing (more or less) any type - particularly useful for things like std::stack: template <class C> void Clear( C & c ) { c = C(); } I have a few more, but I'm interested in which ones you use? Please limit answers to wrapper functions - i.e. no more than a couple of lines of code.

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• Why are references compacted inside Perl lists?

  - by parkan

  Putting a precompiled regex inside two different hashes referenced in a list: my @list = (); my $regex = qr/ABC/; push @list, { 'one' => $regex }; push @list, { 'two' => $regex }; use Data::Dumper; print Dumper(\@list); I'd expect: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => qr/(?-xism:ABC)/ } ]; But instead we get a circular reference: $VAR1 = [ { 'one' => qr/(?-xism:ABC)/ }, { 'two' => $VAR1->[0]{'one'} } ]; This will happen with indefinitely nested hash references and shallowly copied $regex. I'm assuming the basic reason is that precompiled regexes are actually references, and references inside the same list structure are compacted as an optimization (\$scalar behaves the same way). I don't entirely see the utility of doing this (presumably a reference to a reference has the same memory footprint), but maybe there's a reason based on the internal representation Is this the correct behavior? Can I stop it from happening? Aside from probably making GC more difficult, these circular structures create pretty serious headaches. For example, iterating over a list of queries that may sometimes contain the same regular expression will crash the MongoDB driver with a nasty segfault (see https://rt.cpan.org/Public/Bug/Display.html?id=58500)

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• Garbled text when constructing emails with vmime

  - by Klaus Fiedler

  Hey, my Qt C++ program has a part where it needs to send the first 128 characters or so of the output of a bash command to an email address. The output from the tty is captured in a text box in my gui called textEdit_displayOutput and put into my message I built using the Message Builder ( the object m_vmMessage ) Here is the relevant code snippet: m_vmMessage.getTextPart()->setCharset( vmime::charsets::US_ASCII ); m_vmMessage.getTextPart()->setText( vmime::create < vmime::stringContentHandler > ( ui->textEdit_displayOutput->toPlainText().toStdString() ) ); vmime::ref < vmime::message > msg = m_vmMessage.construct(); vmime::utility::outputStreamAdapter out( std::cout ); msg->generate( out ); Giving bash 'ls /' and a newline makes vmime give terminal output like this: ls /=0Abin etc=09 initrd.img.old mnt=09 sbin=09 tmp=09 vmlinuz.o= ld=0Aboot farts=09 lib=09=09 opt=09 selinux usr=0Acdrom home=09 = lost+found=09 proc srv=09 var=0Adev initrd.img media=09 root = Whereas it should look more like this: ls / bin etc initrd.img.old mnt sbin tmp vmlinuz.old boot farts lib opt selinux usr cdrom home lost+found proc srv var dev initrd.img media root sys vmlinuz 18:22> How do I encode the email properly? Does vmime just display it like that on purpose and the actual content of the email is ok?

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• npgsql Leaking Postgres DB Connections: Way to monitor connections?

  - by Alan

  Background: I'm moving my application from npgsql v1 to npgsql v2.0.9. After a few minutes of running my application, I get a System.Exception: Timeout while getting a connection from the pool. The web claims that this is due to leaking connections (opening a db connection, but not properly closing them). So I'm trying to diagnose leaking postgres connections in npgsql. From the various web literature around; one way to diagnose leaking connections is to setup logging on npgsql, and look for the leaking connection warning message in the log. Problem is, I'm not seeing this message in the logs anywhere. I also found utility that monitors npgsql connections, but it's unstable and crashes. So I'm left manually inspecting code. For everyplace that creates an npgsql connection, there is a finally block disposing of it. For everyplace that opens a datareader, CommandBehavior.CloseConnection is used (and the datareader is disposed). Any other places to check or can someone recommend a way to look for leaking pool connections?

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• Windows Service Installation

  - by Goober

  Scenario I have a server, that has NO Visual Studio Installed. It literally has a normal command prompt and nothing installed yet. We don't want to install anything (except the .Net framework which we have already done). We just want to install a bunch of C# Windows Services that we have written. So far I have been installing and running the windows service on my local machine using a "setup and deploy" project that I built into the application, which I could then use to install the service locally. Question How can I install the service on the server? I imagine it can be done from the command prompt only, but what else do I need? - If anything? and where do I put the files that I want to install BEFORE I install them? I imagine I will have to compile the application on my local machine in Visual Studio, then copy it over to the server, and then run an install utility to install it on the server? Any help would be greatly appreciated.

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• ADO.NET Multiple simultaneous reads from an open database.

  - by Deverill

  Answer not needed - my logic was wrong and this question is invalid. Charles helped me see where I went off-tracks. Thanks I have a utility that moves data from one source to another. In the process of writing the record I check to see if it exists and do an update/insert as necessary. The difficulty I have is that as I'm writing the main record info there is a 2nd table for "custom data" that I have to check to see if it exists and do an update/insert for that as well. Example: I may be loading a pencil sharpener that may or may not exist. While I'm writing it into destination it has characteristics such as style, color, etc. and each of them may or may not exist. As written I seem to need to have 2 DataReaders open, one for the sharpener and one to check for and update color. I am new to ADO.NET, but not to programming and it's more complicated than I listed but for sanity's sake I didn't put all the details. My question is: What am I missing? You can't have 2 readers open at the same time on a connection, yet I can't close the first if I'm stepping through all products. It seems inefficient to have 2 connections, readers, etc. for this. Is there a feature of ADO.NET DBs that I'm missing? How would you do it? Thanks!

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• How to set up django-admin.py on windows vista?

  - by shin

  I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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• Asp.net Web Site Administration Tool with SqlCeMembership

  - by Riderman de Sousa Barbosa

  I am developing an application in MVC 3. I installed this provider via Nuget . Basically, it allows to use any part of memberships, rules and profiles with a .sdf (compact) database. I need the "Web Site Administration Tool" use this provider. But I can not use it. Already checked the web.config and everything is ok. When I open the "Web Site Administration Tool" on the Security I click test (any provider) and the error happens. The following images. Error when clicking test "Could not establish a connection to the database. If you have not yet created the SQL Server database, exit the Web Site Administration tool, use the aspnet_regsql command-line utility to create and configure the database, and then return to this tool to set the provider." Here part of my web.config <authentication mode="Forms" /> <membership> <providers> <add connectionStringName="SqlCeServices" applicationName="/" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed" writeExceptionsToEventLog="false" name="SqlCeMembershipProvider" type="ErikEJ.SqlCeMembershipProvider, ErikEJ.SqlCeMembership" /> </providers> </membership> <profile enabled="false"> <providers> <clear /> <add name="SqlCeProfileProvider" type="ErikEJ.SqlCeProfileProvider" connectionStringName="SqlCeServices" applicationName="/" /> </providers> </profile> <roleManager> <providers> <add connectionStringName="SqlCeServices" applicationName="/" writeExceptionsToEventLog="false" name="SqlCeRoleProvider" type="ErikEJ.SqlCeRoleProvider, ErikEJ.SqlCeMembership" /> </providers> </roleManager> <connectionStrings> <add name="SqlCeServices" connectionString="data source=|DataDirectory|\SqlCeAspnetdb.sdf" /> </connectionStrings>

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• How do I find and open a file in a Visual Studio 2005 add-in?

  - by Charles Randall

  I'm making an add-in with Visual Studio 2005 C# to help easily toggle between source and header files, as well as script files that all follow a similar naming structure. However, the directory structure has all of the files in different places, even though they are all in the same project. I've got almost all the pieces in place, but I can't figure out how to find and open a file in the solution based only on the file name alone. So I know I'm coming from, say, c:\code\project\subproject\src\blah.cpp, and I want to open c:\code\project\subproject\inc\blah.h, but I don't necessarily know where blah.h is. I could hardcode different directory paths but then the utility isn't generic enough to be robust. The solution has multiple projects, which seems to be a bit of a pain as well. I'm thinking at this point that I'll have to iterate through every project, and iterate through every project item, to see if the particular file is there, and then get a proper reference to it. But it seems to me there must be an easier way of doing this.

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• Why is Delphi unable to infer the type for a parameter TEnumerable<T>?

  - by deepc

  Consider the following declaration of a generic utility class in Delphi 2010: TEnumerableUtils = class public class function InferenceTest<T>(Param: T): T; class function Count<T>(Enumerable: TEnumerable<T>): Integer; overload; class function Count<T>(Enumerable: TEnumerable<T>; Filter: TPredicate<T>): Integer; overload; end; Somehow the compiler type inference seems to have problems here: var I: Integer; L: TList<Integer>; begin TEnumerableUtils.InferenceTest(I); // no problem here TEnumerableUtils.Count(L); // does not compile: E2250 There is no overloaded version of 'Count' that can be called with these arguments TEnumerableUtils.Count<Integer>(L); // compiles fine end; The first call works as expected and T is correctly inferred as Integer. The second call does not work, unless I also add <Integer -- then it works, as can be seen in the third call. Am I doing something wrong or is the type inference in Delphi just not supporting this (I don't think it is a problem in Java which is why expected it to work in Delphi, too).

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• capturing CMD batch file parameter list; write to file for later processing

  - by BobB

  I have written a batch file that is launched as a post processing utility by a program. The batch file reads ~24 parameters supplied by the calling program, stores them into variables, and then writes them to various text files. Since the max input variable in CMD is %9, it's necessary to use the 'shift' command to repeatedly read and store these individually to named variables. Because the program outputs several similar batch files, the result is opening several CMD windows sequentially, assigning variables and writing data files. This ties up the calling program for too long. It occurs to me that I could free up the calling program much faster if maybe there's a way to write a very simple batch file that can write all the command parameters to a text file, where I can process them later. Basically, just grab the parameter list, write it and done. Q: Is there some way to treat an entire series of parameter data as one big text string and write it to one big variable... and then echo the whole big thing to one text file? Then later read the string into %n variables when there's no program waiting to resume? Parameter list is something like 25 - 30 words, less than 200 characters. Sample parameter list: "First Name" "Lastname" "123 Steet Name Way" "Cityname" ST 12345 1004968 06/01/2010 "Firstname+Lastname" 101738 "On Account" 20.67 xy-1z 1 8.95 3.00 1.39 0 0 239 8.95 Items in quotes are processed as string variables. List is space delimited. Any suggestions?

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• Problem in filtering records using Dataview (C#3.0)

  - by Newbie

  I have a data table . The data table is basically getting populated from excel sheet. And there are many excel sheets. Henceforth, I have written a utility method for accomplishing the same. Now in some of the excel sheets, there are date columns and in some it is not(only text/string). My function is populating the values properly into the datatable from the excell sheet. But there are many blank rows in the excel sheets some are filled with NULL , some with " ". So I need to filter those records (which are NULL or " " ) first before further processing. What I am after is to use a dataview and apply the filter over there. DataView dv = dataTable.DefaultView; dv.RowFilter = ColumnName + " <> ''"; Well by using metedata (GetOleDbSchemaTable(OleDbSchemaGuid.Columns, restrection)) I was able to get the column names from the excel sheet , so getting the column names is not an issue. But the problem is as I said in some Excel sheet there are date fileds some are not. So the Filter condition of the Dataview needs to be proper. If I apply the above logic, and if it encounters a Datafield, it is throwing error Cannot perform '<' operation on System.DateTime and System.String. Could you people please help me out? I need to filter columns(not known at compile time + their data types) which can have NULL and " " I am using C#3.0 Thanks

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• How do I reference my MainViewController from another class?

  - by todd412

  Hi, I am building an iPhone Utility app that uses UIImageView to display an animation. Within the MainViewController's viewDidLoad() method, I am creating an instance of a CustomClass, and then setting up the animations: - (void)viewDidLoad { [super viewDidLoad]; cc = [CustomClass new]; NSArray * imageArray = [[NSArray alloc] initWithObjects: [UIImage imageNamed:@"image-1-off.jpg"], [UIImage imageNamed:@"image-2-off.jpg"], [UIImage imageNamed:@"image-3-off.jpg"], [UIImage imageNamed:@"image-4-off.jpg"], nil]; offSequence = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)]; offSequence.animationImages = imageArray; offSequence.animationDuration = .8; offSequence.contentMode = UIViewContentModeBottomLeft; [self.view addSubview:offSequence]; [offSequence startAnimating]; } That works fine. However, I would like to be able to move all the above code that sets up the UIImageView into my CustomClass. The problem is in the second to last line: [self.view addSubview:offSequence]; I basically need to replace 'self' with a reference to the MainControllerView, so I can call addSubview from within my CustomClass. I tried creating an instance var of CustomClass called mvc and a setter method that takes a reference to the MainViewController as an argument as such: - (void) setMainViewController: (MainViewController *) the_mvc { mvc = the_mvc; } And then I called it within MainViewController like so: [cc setMainController:MainViewController:self]; But this yields all sorts of errors which I can post here, but it strikes me that I may be overcomplicating this. Is there an easier way to reference the MainViewController that instanatiated my CustomClass?

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• DRYing out implementation of ICloneable in several classes

  - by Sarah Vessels

  I have several different classes that I want to be cloneable: GenericRow, GenericRows, ParticularRow, and ParticularRows. There is the following class hierarchy: GenericRow is the parent of ParticularRow, and GenericRows is the parent of ParticularRows. Each class implements ICloneable because I want to be able to create deep copies of instances of each. I find myself writing the exact same code for Clone() in each class: object ICloneable.Clone() { object clone; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter(); // Serialize this object formatter.Serialize(stream, this); stream.Position = 0; // Deserialize to another object clone = formatter.Deserialize(stream); } return clone; } I then provide a convenience wrapper method, for example in GenericRows: public GenericRows Clone() { return (GenericRows)((ICloneable)this).Clone(); } I am fine with the convenience wrapper methods looking about the same in each class because it's very little code and it does differ from class to class by return type, cast, etc. However, ICloneable.Clone() is identical in all four classes. Can I abstract this somehow so it is only defined in one place? My concern was that if I made some utility class/object extension method, it would not correctly make a deep copy of the particular instance I want copied. Is this a good idea anyway?

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• forcing stack w/i 32bit when -m64 -mcmodel=small

  - by chaosless

  have C sources that must compile in 32bit and 64bit for multiple platforms. structure that takes the address of a buffer - need to fit address in a 32bit value. obviously where possible these structures will use natural sized void * or char * pointers. however for some parts an api specifies the size of these pointers as 32bit. on x86_64 linux with -m64 -mcmodel=small tboth static data and malloc()'d data fit within the 2Gb range. data on the stack, however, still starts in high memory. so given a small utility _to_32() such as: int _to_32( long l ) { int i = l & 0xffffffff; assert( i == l ); return i; } then: char *cp = malloc( 100 ); int a = _to_32( cp ); will work reliably, as would: static char buff[ 100 ]; int a = _to_32( buff ); but: char buff[ 100 ]; int a = _to_32( buff ); will fail the assert(). anyone have a solution for this without writing custom linker scripts? or any ideas how to arrange the linker section for stack data, would appear it is being put in this section in the linker script: .lbss : { *(.dynlbss) *(.lbss .lbss.* .gnu.linkonce.lb.*) *(LARGE_COMMON) } thanks!

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• Can the Subversion client (svn) derefence symbolic links as if they were files?

  - by Ryan B. Lynch

  I have a directory on a Linux system that mostly contains symlinks to files on a different filesystem. I'd like to add the directory to a Subversion repository, dereferencing the symlinks in the process (treating them as the files they point to, rather than links). Generally, I'd like to be able to handle any working-copy operations with this behavior, but the 'svn add' command is where it starts, I think. The SVN client utility doesn't appear to have any options related to symlink dereferencing in the working copy. I didn't find any references to this in the manual (http://svnbook.red-bean.com/en/1.5/index.html), either. I found a poster on the SVN users mailing list who asked the same question but never received an answer, here: http://markmail.org/message/ngchfnzlmm43yj7h (That poster ended up using hard links instead of symlinks. That technique is not an option, in my case, because the real underlying files reside on a separate filesystem.) I'm using Subversion v1.6.1 on Fedora 11. For what it's worth, I know that there are alternative tools/techniques that could help approximate this behavior, but which I have to discard for various reasons. I've already considered [and dust-binned] these possibilities: - a "union" mount, merging all of the the directories containing the real files, with the SVN working-copy directory as the "top" layer in the union; - copying/moving the real files to the same filesystem as the SVN working-copy, and using hardlinks instead of symlinks; - non-SVN version control systems. These were all neat ideas, and I'm sure they are good solutions to other problems, but they won't work given the constraints of this environment and situation.

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• How to change the date/time in Python for all modules?

  - by Felix Schwarz

  When I write with business logic, my code often depends on the current time. For example the algorithm which looks at each unfinished order and checks if an invoice should be sent (which depends on the no of days since the job was ended). In these cases creating an invoice is not triggered by an explicit user action but by a background job. Now this creates a problem for me when it comes to testing: I can test invoice creation itself easily However it is hard to create an order in a test and check that the background job identifies the correct orders at the correct time. So far I found two solutions: In the test setup, calculate the job dates relative to the current date. Downside: The code becomes quite complicated as there are no explicit dates written anymore. Sometimes the business logic is pretty complex for edge cases so it becomes hard to debug due to all these relative dates. I have my own date/time accessor functions which I use throughout my code. In the test I just set a current date and all modules get this date. So I can simulate an order creation in February and check that the invoice is created in April easily. Downside: 3rd party modules do not use this mechanism so it's really hard to integrate+test these. The second approach was way more successful to me after all. Therefore I'm looking for a way to set the time Python's datetime+time modules return. Setting the date is usually enough, I don't need to set the current hour or second (even though this would be nice). Is there such a utility? Is there an (internal) Python API that I can use?

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• How to compare 2 complex spreadsheets running in parallel for consistency with each other?

  - by tbone

  I am working on converting a large number of spreadsheets to use a new 3rd party data access library (converting from third party library #1 to third party library #2). fyi: a call to a UDF (user defined function) is placed in a cell, and when that is refreshed, it pulls the data into a pivot table below the formula. Both libraries behave the same and produce the same output, except, small irregularites can arise, such as an additional field being shown in the output pivot table using library #2, which can affect formulas on the sheet if data is being read from the pivot table without using GetPivotData. So I have ~100 of these very complicated (20+ worksheets per workbook) spreadsheets that I have to convert, and run in parallel for a period of time, to see if the output using the new data access library matches the old library. Is there some clever approach to do this, so I don't have to spend a large amount of time analyzing each sheet to determine the specific elements to compare? Two rough ideas that come to mind: 1. just create a Validator workbook that has the same # of worksheets, and simply do a Worbook1!Worksheet1!A1 - Worbook2!Worksheet3!A1 for every possible cell on each sheet 2. roughly the equivalent of #1, but just traverse the cells in the 2 books using VBA, and log any cells that do not match. I don't particularly like either idea, can anyone think of something better than this, maybe some 3rd party utility I could buy?

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• SOAP security in Salesforce

  - by Dean Barnes

  I am trying to change the wsdl2apex code for a web service call header that currently looks like this: <env:Header> <Security xmlns="http://docs.oasis-open.org/wss/oasis-wss-wssecurity-secext-1.1.xsd"> <UsernameToken Id="UsernameToken-4"> <Username>test</Username> <Password>test</Password> </UsernameToken> </Security> </env:Header> to look like this: <soapenv:Header> <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"> <wsse:UsernameToken wsu:Id="UsernameToken-4" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"> <wsse:Username>Test</wsse:Username> <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">Test</wsse:Password> </wsse:UsernameToken> </wsse:Security> </soapenv:Header> One problem is that I can't work out how to change the namespaces for elements (or even if it matters what name they have). A secondary problem is putting the Type attribute onto the Password element. Can any provide any information that might help? Thanks

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• Mercurial CLI is slow in C#?

  - by pATCheS

  I'm writing a utility in C# that will make managing multiple Mercurial repositories easier for the way my team is using it. However, it seems that there is always about a 300 to 400 millisecond delay before I get anything back from hg.exe. I'm using the code below to run hg.exe and hgtk.exe (TortoiseHg's GUI). The code currently includes a Stopwatch and some variables for timing purposes. The delay is roughly the same on multiple runs within the same session. I have also tried specifying the exact path of hg.exe, and got the same result. static string RunCommand(string executable, string path, string arguments) { var psi = new ProcessStartInfo() { FileName = executable, Arguments = arguments, WorkingDirectory = path, UseShellExecute = false, RedirectStandardError = true, RedirectStandardInput = true, RedirectStandardOutput = true, WindowStyle = ProcessWindowStyle.Maximized, CreateNoWindow = true }; var sbOut = new StringBuilder(); var sbErr = new StringBuilder(); var sw = new Stopwatch(); sw.Start(); var process = Process.Start(psi); TimeSpan firstRead = TimeSpan.Zero; process.OutputDataReceived += (s, e) => { if (firstRead == TimeSpan.Zero) { firstRead = sw.Elapsed; } sbOut.Append(e.Data); }; process.ErrorDataReceived += (s, e) => sbErr.Append(e.Data); process.BeginOutputReadLine(); process.BeginErrorReadLine(); var eventsStarted = sw.Elapsed; process.WaitForExit(); var processExited = sw.Elapsed; sw.Reset(); if (process.ExitCode != 0 || sbErr.Length > 0) { Error.Mercurial(process.ExitCode, sbOut.ToString(), sbErr.ToString()); } return sbOut.ToString(); } Any ideas on how I can speed things up? As it is, I'm going to have to do a lot of caching in addition to threading to keep the UI snappy.

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• noncopyable static const member class in template class

  - by Dukales

  I have a non-copyable (inherited from boost::noncopyable) class that I use as a custom namespace. Also, I have another class, that uses previous one, as shown here: #include <boost/utility.hpp> #include <cmath> template< typename F > struct custom_namespace : boost::noncopyable { F sqrt_of_half(F const & x) const { using std::sqrt; return sqrt(x / F(2.0L)); } // ... maybe others are not so dummy const/constexpr methods }; template< typename F > class custom_namespace_user { static ::custom_namespace< F > const custom_namespace_; public : F poisson() const { return custom_namespace_.sqrt_of_half(M_PI); } static F square_diagonal(F const & a) { return a * custom_namespace_.sqrt_of_half(1.0L); } }; template< typename F > ::custom_namespace< F > const custom_namespace_user< F >::custom_namespace_(); this code leads to the next error (even without instantiation): error: no 'const custom_namespace custom_namespace_user::custom_namespace_()' member function declared in class 'custom_namespace_user' The next way is not legitimate: template< typename F ::custom_namespace< F const custom_namespace_user< F ::custom_namespace_ = ::custom_namespace< F (); What should I do to declare this two classes (first as noncopyable static const member class of second)? Is this feaseble?

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• Will Learning C++ Help for Building Fast/No-Additional-Requirements Desktop Applications?

  - by vito

  Will learning C++ help me build native applications with good speed? Will it help me as a programmer, and what are the other benefits? The reason why I want to learn C++ is because I'm disappointed with the UI performances of applications built on top of JVM and .NET. They feel slow, and start slow too. Of course, a really bad programmer can create a slower and sluggish application using C++ too, but I'm not considering that case. One of my favorite Windows utility application is Launchy. And in the Readme.pdf file, the author of the program wrote this: 0.6 This is the first C++ release. As I became frustrated with C#’s large .NET framework requirements and users lack of desire to install it, I decided to switch back to the faster language. I totally agree with the author of Launchy about the .NET framework requirement or even a JRE requirement for desktop applications. Let alone the specific version of them. And some of the best and my favorite desktop applications don't need .NET or Java to run. They just run after installing. Are they mostly built using C++? Is C++ the only option for good and fast GUI based applications? And, I'm also very interested in hearing the other benefits of learning C++.

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• Dealing with multiple generics in a method call

  - by thaBadDawg

  I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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• Simplification / optimization of GPS track

  - by GreyCat

  I've got a GPS track, produces by gpxlogger(1) (supplied as a client for gpsd). GPS receiver updates its coordinates every 1 second, gpxlogger's logic is very simple, it writes down location (lat, lon, ele) and a timestamp (time) received from GPS every n seconds (n = 3 in my case). After writing down a several hours worth of track, gpxlogger saves several megabyte long GPX file that includes several thousands of points. Afterwards, I try to plot this track on a map and use it with OpenLayers. It works, but several thousands of points make using the map a sloppy and slow experience. I understand that having several thousands of points of suboptimal. There are myriads of points that can be deleted without losing almost anything: when there are several points making up roughly the straight line and we're moving with the same constant speed between them, we can just leave the first and the last point and throw anything else. I thought of using gpsbabel for such track simplification / optimization job, but, alas, it's simplification filter works only with routes, i.e. analyzing only geometrical shape of path, without timestamps (i.e. not checking that the speed was roughly constant). Is there some ready-made utility / library / algorithm available to optimize tracks? Or may be I'm missing some clever option with gpsbabel?

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• Setting objct literal property value via asynchronous callback.

  - by typeof

  I'm creating a self-contained javascript utility object that detects advanced browser features. Ideally, my object would look something like this: Support = { borderRadius : false, // values returned by functions gradient : false, // i am defining dataURI : true }; My current problem deals with some code I'm adapting from Weston Ruter's site which detects dataURI support. It attempts to use javascript to create an image with a dataURI source, and uses onload/onerror callbacks to check the width/height. Since onload is asynchronous, I lose my scope and returning true/false does not assign true/false to my object. Here is my attempt: Support = { ... dataURI : function(prop) { prop = prop; // keeps in closure for callback var data = new Image(); data.onload = data.onerror = function(){ if(this.width != 1 || this.height != 1) { that = false; } that = true; } data.src = "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///ywAAAAAAQABAAACAUwAOw=="; return -1; }(this) }; I'm executing the anonymous function immediately, passing this (which I hoped was a reference to Support.dataURI), but unfortunately references the window object -- so the value is always -1. I can get it to work by using an externally defined function to assign the value after the Support object is created... but I don't think it's very clean that way. Is there a way for it to be self-contained? Can the object literal's function reference the property it's assigned to?

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