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  • Why doesn't C# do "simple" type inference on generics?

    - by Ken Birman
    Just curious: sure, we all know that the general case of type inference for generics is undecidable. And so C# won't do any kind of subtyping at all: if Foo<T> is a generic, Foo<int> isn't a subtype of Foo<T>, or Foo<Object> or of anything else you might cook up. And sure, we all hack around this with ugly interface or abstract class definitions. But... if you can't beat the general problem, why not just limit the solution to cases that are easy. For example, in my list above, it is OBVIOUS that Foo<int> is a subtype of Foo<T> and it would be trivial to check. Same for checking against Foo<Object>. So is there some other deep horror that would creep forth from the abyss if they were to just say, aw shucks, we'll do what we can? Or is this just some sort of religious purity on the part of the language guys at Microsoft?

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  • Passing Derived Class Instances as void* to Generic Callbacks in C++

    - by Matthew Iselin
    This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

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  • Given a date range how to calculate the number of weekends partially or wholly within that range?

    - by andybak
    Given a date range how to calculate the number of weekends partially or wholly within that range? (A few definitions as requested: take 'weekend' to mean Saturday and Sunday. The date range is inclusive i.e. the end date is part of the range 'wholly or partially' means that any part of the weekend falling within the date range means the whole weekend is counted.) To simplify I imagine you only actually need to know the duration and what day of the week the initial day is... I darn well now it's going to involve doing integer division by 7 and some logic to add 1 depending on the remainder but I can't quite work out what... extra points for answers in Python ;-) Edit Here's my final code. Weekends are Friday and Saturday (as we are counting nights stayed) and days are 0-indexed starting from Monday. I used onebyone's algorithm and Tom's code layout. Thanks a lot folks. def calc_weekends(start_day, duration): days_until_weekend = [5, 4, 3, 2, 1, 1, 6] adjusted_duration = duration - days_until_weekend[start_day] if adjusted_duration < 0: weekends = 0 else: weekends = (adjusted_duration/7)+1 if start_day == 5 and duration % 7 == 0: #Saturday to Saturday is an exception weekends += 1 return weekends if __name__ == "__main__": days = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'] for start_day in range(0,7): for duration in range(1,16): print "%s to %s (%s days): %s weekends" % (days[start_day], days[(start_day+duration) % 7], duration, calc_weekends(start_day, duration)) print

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  • accessing a method from a button within a class?

    - by flo
    #import "GameObject.h" #import "Definitions.h" @implementation GameObject @synthesize owner; @synthesize state; @synthesize mirrored; @synthesize button; @synthesize switcher; - (id) init { if ( self = [super init] ) { [self setOwner: EmptyField]; button = [UIButton buttonWithType:UIButtonTypeCustom]; [self setSwitcher: FALSE]; } return self; } - (UIButton*) display{ button.frame = CGRectMake(0, 0, GO_Width, GO_Height); [button setBackgroundImage:[UIImage imageNamed:BlueStone] forState:UIControlStateNormal]; [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; return button; } -(void)buttonPressed:(id) sender { //... } } - (void) dealloc { [super dealloc]; } @end Hi! i would like to know if the above is possible somehow within a class (in my case it is called GameObject) or if i HAVE to have the button call a methode in the viewcontroller... the above results with the app crashing. i would call display within a loop on the viewcontroller and id like to change some of the GameObjects instance variables within buttonPressed. Also id like to change some other stuff by calling some other methods from within buttonPressed but i think that will be the lesser of my problems ;) also id like to know how i can pass some variables to the buttonPressed method... cant find it anywhere :( help on this one would be much appreciated ;) thanks flo

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  • Raw types and subtyping

    - by Dmitrii
    We have generic class SomeClass<T>{ } We can write the line: SomeClass s= new SomeClass<String>(); It's ok, because raw type is supertype for generic type. But SomeClass<String> s= new SomeClass(); is correct to. Why is it correct? I thought that type erasure was before type checking, but it's wrong. From Hacker's Guide to Javac When the Java compiler is invoked with default compile policy it performs the following passes: parse: Reads a set of *.java source files and maps the resulting token sequence into AST-Nodes. enter: Enters symbols for the definitions into the symbol table. process annotations: If Requested, processes annotations found in the specified compilation units. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding. flow: Performs data ow analysis on the trees from the previous step. This includes checks for assignments and reachability. desugar: Rewrites the AST and translates away some syntactic sugar. generate: Generates Source Files or Class Files. Generic is syntax sugar, hence type erasure invoked at 6 pass, after type checking, which invoked at 4 pass. I'm confused.

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  • Help with GetGlyphOutline function(WinAPI)

    - by user146780
    I want to use this function to get contours and within these contours, I want to get cubic bezier. I think I have to call it with GGO_BEZIER. What puzzles me is how the return buffer works. "A glyph outline is returned as a series of one or more contours defined by a TTPOLYGONHEADER structure followed by one or more curves. Each curve in the contour is defined by a TTPOLYCURVE structure followed by a number of POINTFX data points. POINTFX points are absolute positions, not relative moves. The starting point of a contour is given by the pfxStart member of the TTPOLYGONHEADER structure. The starting point of each curve is the last point of the previous curve or the starting point of the contour. The count of data points in a curve is stored in the cpfx member of TTPOLYCURVE structure. The size of each contour in the buffer, in bytes, is stored in the cb member of TTPOLYGONHEADER structure. Additional curve definitions are packed into the buffer following preceding curves and additional contours are packed into the buffer following preceding contours. The buffer contains as many contours as fit within the buffer returned by GetGlyphOutline." I'm really not sure how to access the contours. I know that I can change a pointer another type of pointer but i'm not sure how I go about getting the contours based on this documentation. Thanks

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  • Can I join two tables whereby the joined table is sorted by a certain column?

    - by Ferdy
    I'm not much of a database guru so I need some help on a query I'm working on. In my photo community project I want to richly visualize tags by not only showing the tag name and counter (# of images inside them), I also want to show a thumb of the most popular image inside the tag (most karma). The table setup is as follow: Image table holds basic image metadata, important is the karma field Imagefile table holds multiple entries per image, one for each format Tag table holds tag definitions Tag_map table maps tags to images In my usual trial and error query authoring I have come this far: SELECT * FROM (SELECT tag.name, tag.id, COUNT(tag_map.tag_id) as cnt FROM tag INNER JOIN tag_map ON (tag.id = tag_map.tag_id) INNER JOIN image ON tag_map.image_id = image.id INNER JOIN imagefile on image.id = imagefile.image_id WHERE imagefile.type = 'smallthumb' GROUP BY tag.name ORDER BY cnt DESC) as T1 WHERE cnt > 0 ORDER BY cnt DESC [column clause of inner query snipped for the sake of simplicity] This query gives me somewhat what I need. The outer query makes sure that only tags are returned for which there is at least 1 image. The inner query returns the tag details, such as its name, count (# of images) and the thumb. In addition, I can sort the inner query as I want (by most images, alphabetically, most recent, etc) So far so good. The problem however is that this query does not match the most popular image (most karma) of the tag, it seems to always take the most recent one in the tag. How can I make sure that the most popular image is matched with the tag?

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  • Blogger Template: how to change the color of the border css

    - by Lirik
    Hi, I'm trying to change the borders in the style sheet of the template on my blog, but I've never done anything with css so I'm a little bit at a loss... I want to keep the dark background, but I want to create a small border with a slightly different color around my postings. If my guess is correct, then I should modify some of these definitions: body { background:$bgcolor; margin:0; color:$textcolor; font: x-small "Trebuchet MS", Trebuchet, Verdana, Sans-serif; font-size/* */:/**/small; font-size: /**/small; text-align: center; } a:link { color:$linkcolor; text-decoration:none; } a:visited { color:$visitedlinkcolor; text-decoration:none; } a:hover { color:$titlecolor; text-decoration:underline; } a img { border-width:0; } Here is a pastie with the entire template I'm using: http://pastie.org/932535 Is there a quick way to achieve the desired effect? Your help is appreciated!

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  • Independent name of a class

    - by tobi
    We have class lua. In lua class there is a method registerFunc() which is defined: void lua::registerFun() { lua_register( luaState, "asd", luaApi::asd); lua_register( luaState, "zxc", luaApi::zxc); } lua_register is a built-in function from lua library: http://pgl.yoyo.org/luai/i/lua_register it takes static methods from luaApi class as an 3rd argument. Now some programmer wants to use the lua class, so he is forced to create his own class with definitions of the static methods, like: class luaApi { public: static int asd(); static int zxc(); }; and now is the point. I don't want (as a programmer) to create class named exactly "luaApi", but e.g. myClassForLuaApi. But for now it's not possible because it is explicitly written in the code - in lua class: lua_register( luaState, "asd", luaApi::asd); I would have to change it to: lua_register( luaState, "asd", myClassForLuaApi::asd); but I don't want to (let's assume that the programmer has no access there). If it's still not understandable, I give up. :) Thanks.

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  • autotools: no rule to make target all

    - by Raffo
    I'm trying to port an application I'm developing to autotools. I'm not an expert in writing makefiles and it's a requisite for me to be able to use autotools. In particular, the structure of the project is the following: .. ../src/Main.cpp ../src/foo/ ../src/foo/x.cpp ../src/foo/y.cpp ../src/foo/A/k.cpp ../src/foo/A/Makefile.am ../src/foo/Makefile.am ../src/bar/ ../src/bar/z.cpp ../src/bar/w.cpp ../src/bar/Makefile.am ../inc/foo/ ../inc/bar/ ../inc/foo/A ../configure.in ../Makefile.am The root folder of the project contains a "src" folder containing the main of the program AND a number of subfolders containing the other sources of the program. The root of the project also contains an "inc" folder containing the .h files that are nothing more than the definitions of the classes in "src", thus "inc" reflects the structure of "src". I have written the following configure.in in the root: AC_INIT([PNAME], [1.0]) AC_CONFIG_SRCDIR([src/Main.cpp]) AC_CONFIG_HEADER([config.h]) AC_PROG_CXX AC_PROG_CC AC_PROG_LIBTOOL AM_INIT_AUTOMAKE([foreign]) AC_CONFIG_FILES([Makefile src/Makefile src/foo/Makefile src/foo/A/Makefile src/bar/Makefile]) AC_OUTPUT And the following is ../Makefile.am SUBDIRS = src and then in ../src where the main of the project is contained: bin_PROGRAMS = pname gsi_SOURCES = Main.cpp AM_CPPFLAGS = -I../../inc/foo\ -I../../inc/foo/A \ -I../../inc/bar/ pname_LDADD= foo/libfoo.a bar/libbar.a SUBDIRS = foo bar and in ../src/foo noinst_LIBRARIES = libfoo.a libfoo_a_SOURCES = \ x.cpp \ y.cpp AM_CPPFLAGS = \ -I../../inc/foo \ -I../../inc/foo/A \ -I../../inc/bar And the analogous in src/bar. The problem is that after calling automake and autoconf, when calling "make" the compilation fails. In particular, the program enters the directory src, then foo and creates libfoo.a, but the same fail for libbar.a, with the following error: Making all in bar make[3]: Entering directory `/user/Raffo/project/src/bar' make[3]: *** No rule to make target `all'. Stop. I have read the autotools documentation, but I'm not able to find a similar example to the one I am working on. Unfortunately I can't change the directory structure as this is a fixed requisite of the project I'm working on. I don't know if you can help me or give me any hint, but maybe you can guess the error or give me a link to a similar structured example. Thank you.

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  • Is there any reason to use C instead of C++ for embedded development?

    - by Piotr Czapla
    Question I have two compilers on my hardware C++ and C89 I'm thinking about using C++ with classes but without polymorphism (to avoid vtables). The main reasons I’d like to use C++ are: I prefer to use “inline” functions instead of macro definitions. I’d like to use namespaces as I prefixes clutter the code. I see C++ a bit type safer mainly because of templates, and verbose casting. I really like overloaded functions and constructors (used for automatic casting). Do you see any reason to stick with C89 when developing for very limited hardware (4kb of RAM)? Conclusion Thank you for your answers, they were really helpful! I though the subject through and I will stick with C mainly because: It is easier to predict actual code in C and this is really important if you have only 4kb of ram. My team consists of C developers mainly so advance features of C++ won't be frequently used. I've found a way to inline functions in my C compiler (C89). It is hard to accept one answer as you provided so many good answers. Unfortunately I can't create a wiki and accept it so I will choose one answer that made me think most.

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  • Definition of the job titles involved in a software development process.

    - by Rafael Romão
    I have seen many job titles for people involved in a software development process, but never found a consensus about they mean. I know many of them are equivalent, and found some other questions about that here in SO, but I would like to know your definitions and comments about them. I want not only to know if there is really a consensus, but also to know if what I suppose to be a Software Architect, is really a Software Architect, and so on. The job titles I mean are: Developer; System Analyst; Programmer; Analyst Programmer; Software Engineer; Software Architect; Designer; Software Designer; Business Manager; Business Analyst; Program Manager; Project Manager; Development Manager; Tester; Support Analyst; Please, feel free to add more titles to this list in your answers. It would be very helpful.

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  • Highlighting correctly in an emacs major mode

    - by Paul Nathan
    Hi, I am developing an emacs major mode for a language (aka mydsl). However, using the techniques on xahlee's site doesn't seem to be working for some reason (possibly older emacs dialect..) The key issues I am fighting with are (1) highlighting comments is not working and (2), the use of regexp-opt lines is not working. I've reviewed the GNU manual and looked over cc-mode and elisp mode... those are significantly more complicated than I need. ;;;Standard # to newline comment ;;;Eventually should also have %% to %% multiline block comments (defun mydsl-comment-dwim (arg) "comment or uncomment" (interactive "*P") (require 'newcomment) (let ((deactivate-mark nil) (comment-start "#") (comment-end "") comment-dwim arg))) (defvar mydsl-events '("reservedword1" "reservedword2")) (defvar mydsl-keywords '("other-keyword" "another-keyword")) ;;Highlight various elements (setq mydsl-hilite '( ; stuff between " ("\"\\.\\*\\?" . font-lock-string-face) ; : , ; { } => @ $ = are all special elements (":\\|,\\|;\\|{\\|}\\|=>\\|@\\|$\\|=" . font-lock-keyword-face) ( ,(regexp-opt mydsl-keywords 'words) . font-lock-builtin-face) ( ,(regexp-opt mydsl-events 'words) . font-lock-constant-face) )) (defvar mydsl-tab-width nil "Width of a tab for MYDSL mode") (define-derived-mode mydsl-mode fundamental-mode "MYDSL mode is a major mode for editing MYDSL files" ;Recommended by manual (kill-all-local-variables) (setq mode-name "MYDSL script") (setq font-lock-defaults '((mydsl-hilite))) (if (null mydsl-tab-width) (setq tab-width mydsl-tab-width) (setq tab-width default-tab-width) ) ;Comment definitions (define-key mydsl-mode-map [remap comment-dwim] 'mydsl-comment-dwim) (modify-syntax-entry ?# "< b" mydsl-mode-syntax-table) (modify-syntax-entry ?\n "> b" mydsl-mode-syntax-table) ;;A gnu-correct program will have some sort of hook call here. ) (provide 'mydsl-mode)

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  • Sorting out POCO, Repository Pattern, Unit of Work, and ORM

    - by CoffeeAddict
    I'm reading a crapload on all these subjects: POCO Repository Pattern Unit of work Using an ORM mapper ok I see the basic definitions of each in books, etc. but I can't visualize this all together. Meaning an example structure (DL, BL, PL). So what, you have your DL objects that contain your CRUD methods, then your BL objects which are "mapped" using an ORM back to your DL objects? What about DTOs...they're your DL objects right? I'm confused. Can anyone really explain all this together or send me example code? I'm just trying to put this together. I am determining whether to go LINQ to SQL or EF 4 (not sure about NHibrernate yet). Just not getting the concepts as in physical layers and code layers here and what each type of object contains (just properties for DTOs, and CRUDs for your core DL classes that match the table fields???). I just need some guidance here. I'm reading Fowler's books and starting to read Evans but just not all there yet.

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  • how do call a polymorphic function from an agnostic function?

    - by sds
    I have a method foo void foo (String x) { ... } void foo (Integer x) { ... } and I want to call it from a method which does not care about the argument: void bar (Iterable i) { ... for (Object x : i) foo(x); // this is the only time i is used ... } the code above complains that that foo(Object) is not defined and when I add void foo (Object x) { throw new Exception; } then bar(Iterable<String>) calls that instead of foo(String) and throws the exception. How do I avoid having two textually identical definitions of bar(Iterable<String>) and bar(Iterable<Integer>)? I thought I would be able to get away with something like <T> void bar (Iterable<T> i) { ... for (T x : i) foo(x); // this is the only time i is used ... } but then I get cannot find foo(T) error.

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  • Serialized NHibernate Configuration objects - detect out of date or rebuild on demand?

    - by fostandy
    I've been using serialized nhibernate configuration objects (also discussed here and here) to speed up my application startup from about 8s to 1s. I also use fluent-nhibernate, so the path is more like ClassMap class definitions in code fluentconfiguration xml nhibernate configuration configuration serialized to disk. The problem from doing this is that one runs the risk of out of date mappings - if I change the mappings but forget to rebuild the serialized configuration, then I end up using the old mappings without realising it. This does not always result in an immediate and obvious error during testing, and several times the misbehaviour has been a real pain to detect and fix. Does anybody have any idea how I would be able to detect if my classmaps have changed, so that I could either issue an immediate warning/error or rebuild it on demand? At the moment I am comparing timestamps on my compiled assembly against the serialized configuration. This will pickup mapping changes, but unfortunately it generates a massive false positive rate as ANY change to the code results in an out of date flag. I can't move the classmaps to another assembly as they are tightly integrated into the business logic. This has been niggling me for a while so I was wondering if anybody had any suggestions?

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  • eclipse show errors but compiles when external makefile

    - by Anthony
    I have some c++ code using CImg and Eigen libraries. At the c++ code I define a plugin like this #define cimg_plugin1 "my_plugin.h" #include "CImg.h" The plugin contains many method definitions that are used at the c++ code. I also have a makefile that when called from the command line (./make), allows me to compile everything, and generates an executable. I want to import this code into a new Eclipse project, and I do it so: NewProjectC++ projectmakefile projectempty project unmark "Use default location", and select the folder containing my code at the filesystem ProjectpropertiesC/C++ Buildunmark "Use default build command" and set it to use my makefile Also in project propertiesC/C++ GeneralPaths and SymbolsAdd paths to folders containing Eigen and CImg Rebuild index Clean project Restart eclipse When I build the project, eclipse tells me I have more than 1000 errors in "my_plugin.h", but it is capable to generate the executable. Even though, I would like to get rid of this errors, because they are annoying. Also, if I want to open the declaration of CImg methods used at the plugin, I can't. I know it has been asked before, but any of the solutions I found were satisfactory for me (most of them enumerated at the previous list). The sources I visited are the following, and I would be really happy if you find and tell me others I didn't see. Eclipse shows errors but project compile fine eclipse C project shows errors (Symbol could not be resolved) but it compiles Eclipse CDT shows some errors, but the project is successfully built http://www.eclipse.org/forums/index.php/t/247954/

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  • .Net lambda expression-- where did this parameter come from?

    - by larryq
    I'm a lambda newbie, so if I'm missing vital information in my description please tell me. I'll keep the example as simple as possible. I'm going over someone else's code and they have one class inheriting from another. Here's the derived class first, along with the lambda expression I'm having trouble understanding: class SampleViewModel : ViewModelBase { private ICustomerStorage storage = ModelFactory<ICustomerStorage>.Create(); public ICustomer CurrentCustomer { get { return (ICustomer)GetValue(CurrentCustomerProperty); } set { SetValue(CurrentCustomerProperty, value); } } private int quantitySaved; public int QuantitySaved { get { return quantitySaved; } set { if (quantitySaved != value) { quantitySaved = value; NotifyPropertyChanged(p => QuantitySaved); //where does 'p' come from? } } } public static readonly DependencyProperty CurrentCustomerProperty; static SampleViewModel() { CurrentCustomerProperty = DependencyProperty.Register("CurrentCustomer", typeof(ICustomer), typeof(SampleViewModel), new UIPropertyMetadata(ModelFactory<ICustomer>.Create())); } //more method definitions follow.. Note the call to NotifyPropertyChanged(p => QuantitySaved) bit above. I don't understand where the "p" is coming from. Here's the base class: public abstract class ViewModelBase : DependencyObject, INotifyPropertyChanged, IXtremeMvvmViewModel { public event PropertyChangedEventHandler PropertyChanged; protected virtual void NotifyPropertyChanged<T>(Expression<Func<ViewModelBase, T>> property) { MvvmHelper.NotifyPropertyChanged(property, PropertyChanged); } } There's a lot in there that's not germane to the question I'm sure, but I wanted to err on the side of inclusiveness. The problem is, I don't understand where the 'p' parameter is coming from, and how the compiler knows to (evidently?) fill in a type value of ViewModelBase from thin air? For fun I changed the code from 'p' to 'this', since SampleViewModel inherits from ViewModelBase, but I was met with a series of compiler errors, the first one of which statedInvalid expression term '=>' This confused me a bit since I thought that would work. Can anyone explain what's happening here?

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  • Managing multiple customer databases in ASP.NET MVC application

    - by Robert Harvey
    I am building an application that requires separate SQL Server databases for each customer. To achieve this, I need to be able to create a new customer folder, put a copy of a prototype database in the folder, change the name of the database, and attach it as a new "database instance" to SQL Server. The prototype database contains all of the required table, field and index definitions, but no data records. I will be using SMO to manage attaching, detaching and renaming the databases. In the process of creating the prototype database, I tried attaching a copy of the database (companion .MDF, .LDF pair) to SQL Server, using Sql Server Management Studio, and discovered that SSMS expects the database to reside in c:\program files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\MyDatabaseName.MDF Is this a "feature" of SQL Server? Is there a way to manage individual databases in separate directories? Or am I going to have to put all of the customer databases in the same directory? (I was hoping for a little better control than this). NOTE: I am currently using SQL Server Express, but for testing purposes only. The production database will be SQL Server 2008, Enterprise version. So "User Instances" are not an option.

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  • Ruby TypeErrors involving `expected Data`

    - by Kenny Peng
    I've ran into situations where I have gotten these expected Data errors before, but they have always pointed to ActiveRecord not playing well with other libraries in the past. This piece of code: def load(kv_block, debug=false) # Converts a string block to a Hash using split kv_map = StringUtils.kv_array_to_hash(kv_block) # Loop through each key, value kv_map.each do |mem,val| # Format the member from camel case to underscore member = mem.camel_to_underscore() # If the object includes a method to set the key (i.e. the key # is a member of self), invoke the method, setting the value of # the member) if self.methods.include?(member.to_set_method_name()) then # Exception thrown here self.send(member.to_set_method_name(), val) # Else, check for the same case, this time for an instance variable elsif self.instance_variable_defined?(member.to_instance_var_name()) self.instance_variable_set(member.to_instance_var_name(), val) # Else, complain that the object doesn't understand the key with # respect to its class definition. else raise ArgumentError, "I don't know what to do with #{member}. #{self.class} does not have a member or function called #{member}" end end end produces the error wrong argument type #<Class:0x11a02088> (expected Data) (TypeError) in the each loop on the first if test. I've inspected a post-mortem debugging instance using rdebug, and running that line manually, it works without a hitch. Has anyone seen this error before and what's been your solution to it? I used to think it was ActiveRecord and other gems stomping on each other's definitions, but I removed any references to ActiveRecord and this still occurs.

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  • C++ VB6 interfacing problem

    - by Roshan
    Hi, I'm tearing my hair out trying to solve this one, any insights will be much appreciated: I have a C++ exe which acquires data from some hardware in the main thread and processes it in another thread (thread 2). I use a c++ dll to supply some data processing functions which are called from thread 2. I have a requirement to make another set of data processing functions in VB6. I have thus created a VB6 dll, using the add-in vbAdvance to create a standard dll. When I call functions from within this VB6 dll from the main thread, everything works exactly as expected. When I call functions from this VB6 dll in thread 2, I get an access violation. I've traced the error to the CopyMemory command, it would seem that if this is used within the call from the main thread, it's fine but in a call from the process thread, it causes an exception. Why should this be so? As far as I understand, threads share the same address space. Here is the code from my VB dll Public Sub UserFunInterface(ByVal in1ptr As Long, ByVal out1ptr As Long, ByRef nsamples As Long) Dim myarray1() As Single Dim myarray2() As Single Dim i As Integer ReDim myarray1(0 To nsamples - 1) As Single ReDim myarray2(0 To nsamples - 1) As Single With tsa1din(0) ' defined as safearray1d in a global definitions module .cDims = 1 .cbElements = 4 .cElements = nsamples .pvData = in1ptr End With With tsa1dout .cDims = 1 .cbElements = 4 .cElements = nsamples .pvData = out1ptr End With CopyMemory ByVal VarPtrArray(myarray1), VarPtr(tsa1din(0)), 4 CopyMemory ByVal VarPtrArray(myarray2), VarPtr(tsa1dout), 4 For i = 0 To nsamples - 1 myarray2(i) = myarray1(i) * 2 Next i ZeroMemory ByVal VarPtrArray(myarray1), 4 ZeroMemory ByVal VarPtrArray(myarray2), 4 End Sub

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  • SPRING: How do you programmatically instantiate classes based on information passed from Flex UI

    - by babyangel86
    Imagine the UI passes back an XMl node as such: <properties> <type> Source </type> <name> Blooper </name> <delay> <type> Deterministic </type> <parameters> <param> 4 </param> </parameters> <delay> <batch> <type> Erlang </type> <parameters> <param> 4 </param> <param> 6 </param> </parameters> <batch> And behind the scene what it is asking that you instantiate a class as such: new Source("blooper", new Exp(4), new Erlang(4,6); The problem lies in the fact that you don't know what class you will need to processing, and you will be sent a list of these class definitions with instructions on how they can be linked to each other. I've heard that using a BeanFactoryPostProcessor might be helpful, or a property editor/convertor. However I am at a loss as to how best to use them to solve my problem. Any help you can provide will be much appreciated.

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  • How can I set the default value for a custom "Number" field in SharePoint?

    - by UnhipGlint
    I created a custom field for a content type I am creating using the XML below. <field ID="{GUID}" Required="False" DisplayName="Likes" Name="Likes" Type="Number" SourceID="http://schemas.microsoft.com/sharepoint/v3"><default>0</default></field> The field is meant to be used as a counter of sorts, and will be incremented programmatically. But, I can't get the value to default to "0" when a new item is created. However, for some reason, when I create a new column manually using the Site Collection settings page and configure it to default to "0" it works as it should. So far, I've tried the following tactics: I removed the "default" element from the field definition, and set the "DefaultValue" attribute on the content type definition. I exported a definition for the manually-created, working column (using an Imtech STSADM tool). Then, I added it to my field definitions XML and modified the IDs so that I could add it to my content type. When I did this, it still didn't work, even though it was exported from a working column! Any idea why this isn't working for me?

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  • Visual Studio - Edit source code located in a database

    - by mfeingold
    I am building something similar to Server Explorer for Apache CouchDB. One of the things necessary is to be able to edit CouchDB view definitions which in CouchDB are JavaScript functions. How can I trick Visual Studio into using my object to retrieve and save the content of the JavaScript function but still use the rest of it - I am happy with editor itself and have no intention of writing my own Editor/Language Service, etc. The latter would be much bigger effort than what this project warrants Edit After more digging I am still stuck. Here is what I know: IVsUIShellOpenDocument interface provides a method OpenStandardEditor which can be used to open the standard Visual Studio editor. As one of the parameters this method takes a Pointer to the IUnknown interface of the document data object. This object is supposed to implement several interfaces described in many places all over the MSDN. Visual Studio SDK also provides a 'sample' implementation of the document data object VsTextBufferClass. I can create an instance of this class and when I pass the pointer to the instance to the OpenStandardEditor I can see my editor and it seems to work ok. When I try to implement my own class implementing the same interfaces (IVsTextBuffer, VsTextBuffer, IVsTextLines) OpenStandardEditor method returns success, but VS bombs out on call editor.Show() with an access violation. My suspicion is that VsTextBufferClass also implements some other interface(s) but not in C# way but rather in the good old COM way. I just do not know which one(s). Any thoughts?

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  • Is it possible to change 2-3 times f->SetSensor() ?

    - by Asen
    Hello there ! i use cocos2d-iphone-0.99.2 and integrated in it box2d. i have 2 kind of sprites with tags 1 and 2. Also i created bodies and shape definitions for them. what i'm trying to do is to make sprite1 kinds to act as solid or act as not solid when sprite2 colides with them. i tried this code : for(b2Body *b = _world->GetBodyList(); b; b=b->GetNext()) { if (b-GetUserData() != NULL) { CCSprite *sprite = (CCSprite )b-GetUserData(); if (sprite.tag == 1) { b2Fixture f = b-GetFixtureList(); f-SetSensor(solid); } } } Where solid is bool. The first time when i change fixture to sensor everything is just fine but when i try to revert and change again to solid my app crashes with the following error : Assertion failed: (manifold-pointCount 0), function b2ContactSolver, file /Documents/myapp/libs/Box2D/Dynamics/Contacts/b2ContactSolver.cpp, line 58. Is it possible somehow to change fixture-SetSensor several times and if so ... how ? Any help is highly appreciated.

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