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  • Rails 2.3.5: How does one add an error when it doesn't make sense to put it in a validation?

    - by randombits
    I recently was trying to add errors.add_to_base code in the middle of some model logic and was wondering why it wasn't showing up in my view that was iterating over all errors. I then ran across this e-mail which explains why: http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/e045ec1dead1ff06?pli=1 The question is then, how does one add errors with add_to_base if it doesn't make sense to put them into a validate method? I have some complex logic. The model needs to talk to a has_many relationship which has its own relationships that go through a myriad of conditionals to figure out if a request makes sense. It's nothing that can be tied to a validate method easily. How does one add errors then accordingly?

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  • how to databind a datalist's page index to a button's commandname?

    - by korben
    i got this inside a button inside a datalist CommandName="<%# Container.ItemIndex %>" when i click the button, i'm expecting commandname to = 0, then 1, then 2, etc, as the datalist progresses, and i'm using that value in the button click's c# but i'm getting this error, i'm pretty sure i'm using this exact setup on another page and i have no problems, any idea what's going on? Server Error in '/' Application. Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: CS0117: 'System.Web.UI.Control' does not contain a definition for 'ItemIndex'

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  • @ExceptionHandler doesn't handle the thrown exceptions

    - by Javi
    Hello, I have a method in my controller which will handle the exceptions thrown by the application. So I have a method like this one. @Controller public class ExceptionController { @RequestMapping(value="/error") @ExceptionHandler(value={Exception.class, NullPointerException.class}) public String showError(Exception e, Model model){ return "tiles:error"; } } And to try I if it works I throw a NullPointerException in another method in other method controller: boolean a = true; if(a){ throw new NullPointerException(); } After the exception is thrown it is printed in the JSP, but it doesn't go throw my showError() method (I've set a breakpoint there and it never enters). showError() method will catch the exception and will show different error pages depending on the exception type (though now it always shows the same error page). If I go to the url /error it shows the error page so the showError() method is OK. I'm using Spring 3. What can be the problem? Thanks.

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  • CMD Execption Handling C/C++

    - by ciyo
    I will use some CMD commands in my program and these commands might throw some exceptions. And as you know, when an exception accours, CMD writes its own error message the screen. But, I want to write my own error message. My question is this: Is there a way to block CMD messages and write only my own error messages? P.S. This is not a complex program. It executes CMD commands using System(). Example: Let's say, the user can rename and copy any files in the program. As you know, if the user does not enter file's path properly, an error message is showed on the screen. And I want that this error message never appears on the screen. Only my own error message is showed. Thank you!

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  • MySQL transaction conundrum

    - by David Faitelson
    I need to perform several inserts in a single atomic transaction. For example: start transaction; insert ... insert ... commit; However when MySQL encounters an error it aborts only the particular statement that caused the error. For example, if there is an error in the second insert statement the commit will still take place and the first insert statement will be recorded. Thus, when errors occur a MySQL transaction is not really a transaction. To overcome this problem I have used an error exit handler where I rollback the transaction. Now the transaction is silently aborted but I don't know what was the problem. So here is the conundrum for you: How can I both make MySQL abort a transaction when it encounters an error, and pass the error code on to the caller?

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  • How to remove .zip file in c on windows? (error: Directory not empty)

    - by ExtremeBlue
    include include include include "win32-dirent.h" include include include define MAXFILEPATH 1024 bool IsDirectory(char* path) { WIN32_FIND_DATA w32fd; HANDLE hFindFile; hFindFile = FindFirstFile((PTCHAR)path, &w32fd); if(hFindFile == INVALID_HANDLE_VALUE) { return false; } return w32fd.dwFileAttributes & (FILE_ATTRIBUTE_DIRECTORY); } int RD(const char* folderName) { DIR *dir; struct dirent *ent; dir = opendir(folderName); if(dir != NULL) { while((ent = readdir(dir)) != NULL) { if(strcmp(ent->d_name , ".") == 0 || strcmp(ent->d_name, "..") == 0) { continue; } char fileName[MAXFILEPATH]; sprintf(fileName,"%s%c%s", folderName, '\\', ent->d_name); if(IsDirectory(fileName)) { RD(fileName); } else { unlink(fileName); } } closedir(dir); //chmod(folderName, S_IWRITE | S_IREAD); if(_rmdir(folderName) != 0)perror(folderName); } else { printf("%s <%s>\n","Could Not Open Directory.", folderName); return -1; } return 0; } int main(int argc, char* argv[]) { if(argc < 2) { printf("usage: ./a.out \n"); return 1; } //RD(argv[1]); //_mkdir("12"); //_mkdir("12\\34"); //_rmdir("12\\34"); //_rmdir("12"); char buf[0xff]; sprintf(buf, "unzip -x -q -d 1234 1234.zip"); system(buf); RD("1234"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56\\5.txt"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56\\6.txt"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\1_23.zip"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\4.txt"); //_rmdir("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56"); //_rmdir("D:\\dev\\c\\project\\removeFolder\\Debug\\1234"); return 0; } Archive: 1234.zip inflating: 1234/4.txt inflating: 1234/56/5.txt inflating: 1234/56/6.txt inflating: 1234/1_23.zip

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  • nested list comprehension using intermediate result

    - by KentH
    I am trying to grok the output of a function which doesn't have the courtesy of setting a result code. I can tell it failed by the "error:" string which is mixed into the stderr stream, often in the middle of a different conversion status message. I have the following list comprehension which works, but scans for the "error:" string twice. Since it is only rescanning the actual error lines, it works fine, but it annoys me I can't figure out how to use a single scan. Here's the working code: errors = [e[e.find('error:'):] for e in err.splitlines() if 'error:' in e] The obvious (and wrong) way to simplify is to save the "find" result errors = [e[i:] for i in e.find('error:') if i != -1 for e in err.splitlines()] However, I get "UnboundLocalError: local variable 'e' referenced before assignment". Blindly reversing the 'for's in the comprehension also fails. How is this done? THanks. Kent

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  • Uploading an image file with Paperclip (in RoR) causing error.

    - by mtay
    This should be a simple thing to do, but I'm running into a wall and I'm not sure how to debug this response. In my Image model, I have: class Image < ActiveRecord::Base has_attached_file :image, :styles => { :display => "500x500>", :thumbnail => "95x95>"} Then in my Views, my form contains this: -form_for @image, :html => { :multipart => true } do |image| %tr %td.woc_left =label_tag :image, 'photo to upload', :class => 'required' %td.woc_center =image.file_field :image In my Mysql table, I have a column called "image_file_name" (string). However, when I try to upload an image and submit it, I see 2 errors prohibited this from being saved There were problems with the following fields: Image Paperclip::CommandNotFoundError Image Paperclip::CommandNotFoundError What am I doing wrong? Thank you for your help!

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  • how to avoid the error due to missing element from an XML file in Flash Action Script

    - by coderex
    Hi, I have a code which is written for read the xml data. and the xml file contains the optional values, so some time the elements are present there some times not. In this case how can i set a default value for that in action script 3.0. When i tried to trace the value that area is skipping. So is there any other method to trace-out is that element is present or not something like that??

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  • Error in value of default parameter [Bug in Visual C++ 2008?]

    - by HellBoy
    I am facing following issue while trying to use template in my code I have some C++ code which i call from C functions. Problem is I am getting different values in the following code for statement 1 and 2. Type id : unsigned int statement 1 : 4 statement 2 : 1 C++ Code : template <typename T> void func(T* value, unsigned int len = sizeof(T)) { cout << "Type id : " << typeid(T).name() << endl; cout << "statement 1 " << sizeof(T) << endl; cout << "statement 2 " << len << endl; } template <typename T> void func1(T data) { T val = data; func(&val); } C Code : void test(void *ptr, unsigned int len) { switch(len) { case 1: func1(*(static_cast<uint32_t *>(ptr)) break; } } This happens only on windows. On Linux it works fine.

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  • What is wrong in this bit of MyID3 code? (error code is just Exceptions)

    - by user3697621
    Okay, so, this was supposed to get the paths of all mp3 files in a folder, read their metadata and put in an arraylist. public static List<String> OrgMetadata(List<String> rawgenrelist){ File folder = new File("C:\\SOM\\"); File[] listOfFiles = folder.listFiles(); //File path = listOfFiles; for (int i = 0; i < listOfFiles.length; i++) { String pt = listOfFiles[i].getAbsolutePath(); File src = new File(pt); MusicMetadataSet src_set = new MyID3().read(src); if (src_set != null && listOfFiles[i].isFile()) { IMusicMetadata metadata = src_set.getSimplified(); rawgenrelist.add(metadata.getGenreName()); } } List<String> genrelist; genrelist = new ArrayList(new HashSet(rawgenrelist)); return genrelist; }

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  • C: Why does gcc allow char array initialization with string literal larger than array?

    - by Ashwin
    int main() { char a[7] = "Network"; return 0; } A string literal in C is terminated internally with a nul character. So, the above code should give a compilation error since the actual length of the string literal Network is 8 and it cannot fit in a char[7] array. However, gcc (even with -Wall) on Ubuntu compiles this code without any error or warning. Why does gcc allow this and not flag it as compilation error? gcc only gives a warning (still no error!) when the char array size is smaller than the string literal. For example, it warns on: char a[6] = "Network"; [Related] Visual C++ 2012 gives a compilation error for char a[7]: 1>d:\main.cpp(3): error C2117: 'a' : array bounds overflow 1> d:\main.cpp(3) : see declaration of 'a'

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  • "The breakpoint will not currently be hit" error while debugging a mixed mode application (c# and unmanaged c++)

    - by user1678403
    While debugging a mixed mode application in VS2010, the breakpoint set on a line of code contained in an unmanaged c++ dll source file (called from a managed c# wrapper class) shows the infamous "The breakpoint will not currently be hit. No symbols have been loaded for this document" info message when hovering the mouse over the breakpoint on the line in question. The breakpoint itself is a red circle with a yellow info triangle instead of the usual solid red orb. Of course, the breakpoint isn't hit when the debugger is executed. Most answers I've found for this warning indicate the breakpoint hasn't been set properly, or that the expected dll is not being loaded, or that the associated pdb file is not located in the correct location, etc. etc. This is not the problem. The application does load and execute the referenced dll correctly. I've verified that the correct pdb file, with the same file date as its dll, is located in the executable's working directory along with the target dll itself. The debugger simply doesn't load the symbols for the dll, and the dll doesn't show in the Modules list. None of the solutions I've found online work for this problem. The dll doesn't show in the modules list available from 'Debug-Windows-Modules' menu selection... even though it is, in fact, loaded. Breakpoints set in the wrapper class work correctly. Deleting the bin and obj directories, cleaning and rebuilding the solution also doesn't help.

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  • Parallelism in .NET – Part 3, Imperative Data Parallelism: Early Termination

    - by Reed
    Although simple data parallelism allows us to easily parallelize many of our iteration statements, there are cases that it does not handle well.  In my previous discussion, I focused on data parallelism with no shared state, and where every element is being processed exactly the same. Unfortunately, there are many common cases where this does not happen.  If we are dealing with a loop that requires early termination, extra care is required when parallelizing. Often, while processing in a loop, once a certain condition is met, it is no longer necessary to continue processing.  This may be a matter of finding a specific element within the collection, or reaching some error case.  The important distinction here is that, it is often impossible to know until runtime, what set of elements needs to be processed. In my initial discussion of data parallelism, I mentioned that this technique is a candidate when you can decompose the problem based on the data involved, and you wish to apply a single operation concurrently on all of the elements of a collection.  This covers many of the potential cases, but sometimes, after processing some of the elements, we need to stop processing. As an example, lets go back to our previous Parallel.ForEach example with contacting a customer.  However, this time, we’ll change the requirements slightly.  In this case, we’ll add an extra condition – if the store is unable to email the customer, we will exit gracefully.  The thinking here, of course, is that if the store is currently unable to email, the next time this operation runs, it will handle the same situation, so we can just skip our processing entirely.  The original, serial case, with this extra condition, might look something like the following: foreach(var customer in customers) { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) break; customer.LastEmailContact = DateTime.Now; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, we’re processing our loop, but at any point, if we fail to send our email successfully, we just abandon this process, and assume that it will get handled correctly the next time our routine is run.  If we try to parallelize this using Parallel.ForEach, as we did previously, we’ll run into an error almost immediately: the break statement we’re using is only valid when enclosed within an iteration statement, such as foreach.  When we switch to Parallel.ForEach, we’re no longer within an iteration statement – we’re a delegate running in a method. This needs to be handled slightly differently when parallelized.  Instead of using the break statement, we need to utilize a new class in the Task Parallel Library: ParallelLoopState.  The ParallelLoopState class is intended to allow concurrently running loop bodies a way to interact with each other, and provides us with a way to break out of a loop.  In order to use this, we will use a different overload of Parallel.ForEach which takes an IEnumerable<T> and an Action<T, ParallelLoopState> instead of an Action<T>.  Using this, we can parallelize the above operation by doing: Parallel.ForEach(customers, (customer, parallelLoopState) => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) parallelLoopState.Break(); else customer.LastEmailContact = DateTime.Now; } }); There are a couple of important points here.  First, we didn’t actually instantiate the ParallelLoopState instance.  It was provided directly to us via the Parallel class.  All we needed to do was change our lambda expression to reflect that we want to use the loop state, and the Parallel class creates an instance for our use.  We also needed to change our logic slightly when we call Break().  Since Break() doesn’t stop the program flow within our block, we needed to add an else case to only set the property in customer when we succeeded.  This same technique can be used to break out of a Parallel.For loop. That being said, there is a huge difference between using ParallelLoopState to cause early termination and to use break in a standard iteration statement.  When dealing with a loop serially, break will immediately terminate the processing within the closest enclosing loop statement.  Calling ParallelLoopState.Break(), however, has a very different behavior. The issue is that, now, we’re no longer processing one element at a time.  If we break in one of our threads, there are other threads that will likely still be executing.  This leads to an important observation about termination of parallel code: Early termination in parallel routines is not immediate.  Code will continue to run after you request a termination. This may seem problematic at first, but it is something you just need to keep in mind while designing your routine.  ParallelLoopState.Break() should be thought of as a request.  We are telling the runtime that no elements that were in the collection past the element we’re currently processing need to be processed, and leaving it up to the runtime to decide how to handle this as gracefully as possible.  Although this may seem problematic at first, it is a good thing.  If the runtime tried to immediately stop processing, many of our elements would be partially processed.  It would be like putting a return statement in a random location throughout our loop body – which could have horrific consequences to our code’s maintainability. In order to understand and effectively write parallel routines, we, as developers, need a subtle, but profound shift in our thinking.  We can no longer think in terms of sequential processes, but rather need to think in terms of requests to the system that may be handled differently than we’d first expect.  This is more natural to developers who have dealt with asynchronous models previously, but is an important distinction when moving to concurrent programming models. As an example, I’ll discuss the Break() method.  ParallelLoopState.Break() functions in a way that may be unexpected at first.  When you call Break() from a loop body, the runtime will continue to process all elements of the collection that were found prior to the element that was being processed when the Break() method was called.  This is done to keep the behavior of the Break() method as close to the behavior of the break statement as possible. We can see the behavior in this simple code: var collection = Enumerable.Range(0, 20); var pResult = Parallel.ForEach(collection, (element, state) => { if (element > 10) { Console.WriteLine("Breaking on {0}", element); state.Break(); } Console.WriteLine(element); }); If we run this, we get a result that may seem unexpected at first: 0 2 1 5 6 3 4 10 Breaking on 11 11 Breaking on 12 12 9 Breaking on 13 13 7 8 Breaking on 15 15 What is occurring here is that we loop until we find the first element where the element is greater than 10.  In this case, this was found, the first time, when one of our threads reached element 11.  It requested that the loop stop by calling Break() at this point.  However, the loop continued processing until all of the elements less than 11 were completed, then terminated.  This means that it will guarantee that elements 9, 7, and 8 are completed before it stops processing.  You can see our other threads that were running each tried to break as well, but since Break() was called on the element with a value of 11, it decides which elements (0-10) must be processed. If this behavior is not desirable, there is another option.  Instead of calling ParallelLoopState.Break(), you can call ParallelLoopState.Stop().  The Stop() method requests that the runtime terminate as soon as possible , without guaranteeing that any other elements are processed.  Stop() will not stop the processing within an element, so elements already being processed will continue to be processed.  It will prevent new elements, even ones found earlier in the collection, from being processed.  Also, when Stop() is called, the ParallelLoopState’s IsStopped property will return true.  This lets longer running processes poll for this value, and return after performing any necessary cleanup. The basic rule of thumb for choosing between Break() and Stop() is the following. Use ParallelLoopState.Stop() when possible, since it terminates more quickly.  This is particularly useful in situations where you are searching for an element or a condition in the collection.  Once you’ve found it, you do not need to do any other processing, so Stop() is more appropriate. Use ParallelLoopState.Break() if you need to more closely match the behavior of the C# break statement. Both methods behave differently than our C# break statement.  Unfortunately, when parallelizing a routine, more thought and care needs to be put into every aspect of your routine than you may otherwise expect.  This is due to my second observation: Parallelizing a routine will almost always change its behavior. This sounds crazy at first, but it’s a concept that’s so simple its easy to forget.  We’re purposely telling the system to process more than one thing at the same time, which means that the sequence in which things get processed is no longer deterministic.  It is easy to change the behavior of your routine in very subtle ways by introducing parallelism.  Often, the changes are not avoidable, even if they don’t have any adverse side effects.  This leads to my final observation for this post: Parallelization is something that should be handled with care and forethought, added by design, and not just introduced casually.

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  • Back to Basics: When does a .NET Assembly Dependency get loaded

    - by Rick Strahl
    When we work on typical day to day applications, it's easy to forget some of the core features of the .NET framework. For me personally it's been a long time since I've learned about some of the underlying CLR system level services even though I rely on them on a daily basis. I often think only about high level application constructs and/or high level framework functionality, but the low level stuff is often just taken for granted. Over the last week at DevConnections I had all sorts of low level discussions with other developers about the inner workings of this or that technology (especially in light of my Low Level ASP.NET Architecture talk and the Razor Hosting talk). One topic that came up a couple of times and ended up a point of confusion even amongst some seasoned developers (including some folks from Microsoft <snicker>) is when assemblies actually load into a .NET process. There are a number of different ways that assemblies are loaded in .NET. When you create a typical project assemblies usually come from: The Assembly reference list of the top level 'executable' project The Assembly references of referenced projects Dynamically loaded at runtime via AppDomain/Reflection loading In addition .NET automatically loads mscorlib (most of the System namespace) the boot process that hosts the .NET runtime in EXE apps, or some other kind of runtime hosting environment (runtime hosting in servers like IIS, SQL Server or COM Interop). In hosting environments the runtime host may also pre-load a bunch of assemblies on its own (for example the ASP.NET host requires all sorts of assemblies just to run itself, before ever routing into your user specific code). Assembly Loading The most obvious source of loaded assemblies is the top level application's assembly reference list. You can add assembly references to a top level application and those assembly references are then available to the application. In a nutshell, referenced assemblies are not immediately loaded - they are loaded on the fly as needed. So regardless of whether you have an assembly reference in a top level project, or a dependent assembly assemblies typically load on an as needed basis, unless explicitly loaded by user code. The same is true of dependent assemblies. To check this out I ran a simple test: I have a utility assembly Westwind.Utilities which is a general purpose library that can work in any type of project. Due to a couple of small requirements for encoding and a logging piece that allows logging Web content (dependency on HttpContext.Current) this utility library has a dependency on System.Web. Now System.Web is a pretty large assembly and generally you'd want to avoid adding it to a non-Web project if it can be helped. So I created a Console Application that loads my utility library: You can see that the top level Console app a reference to Westwind.Utilities and System.Data (beyond the core .NET libs). The Westwind.Utilities project on the other hand has quite a few dependencies including System.Web. I then add a main program that accesses only a simple utillity method in the Westwind.Utilities library that doesn't require any of the classes that access System.Web: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); } StringUtils.NewStringId() calls into Westwind.Utilities, but it doesn't rely on System.Web. Any guesses what the assembly list looks like when I stop the code on the ReadLine() command? I'll wait here while you think about it… … … So, when I stop on ReadLine() and then fire up Process Explorer and check the assembly list I get: We can see here that .NET has not actually loaded any of the dependencies of the Westwind.Utilities assembly. Also not loaded is the top level System.Data reference even though it's in the dependent assembly list of the top level project. Since this particular function I called only uses core System functionality (contained in mscorlib) there's in fact nothing else loaded beyond the main application and my Westwind.Utilities assembly that contains the method accessed. None of the dependencies of Westwind.Utilities loaded. If you were to open the assembly in a disassembler like Reflector or ILSpy, you would however see all the compiled in dependencies. The referenced assemblies are in the dependency list and they are loadable, but they are not immediately loaded by the application. In other words the C# compiler and .NET linker are smart enough to figure out the dependencies based on the code that actually is referenced from your application and any dependencies cascading down into the dependencies from your top level application into the referenced assemblies. In the example above the usage requirement is pretty obvious since I'm only calling a single static method and then exiting the app, but in more complex applications these dependency relationships become very complicated - however it's all taken care of by the compiler and linker figuring out what types and members are actually referenced and including only those assemblies that are in fact referenced in your code or required by any of your dependencies. The good news here is: That if you are referencing an assembly that has a dependency on something like System.Web in a few places that are not actually accessed by any of your code or any dependent assembly code that you are calling, that assembly is never loaded into memory! Some Hosting Environments pre-load Assemblies The load behavior can vary however. In Console and desktop applications we have full control over assembly loading so we see the core CLR behavior. However other environments like ASP.NET for example will preload referenced assemblies explicitly as part of the startup process - primarily to minimize load conflicts. Specifically ASP.NET pre-loads all assemblies referenced in the assembly list and the /bin folder. So in Web applications it definitely pays to minimize your top level assemblies if they are not used. Understanding when Assemblies Load To clarify and see it actually happen what I described in the first example , let's look at a couple of other scenarios. To see assemblies loading at runtime in real time lets create a utility function to print out loaded assemblies to the console: public static void PrintAssemblies() { var assemblies = AppDomain.CurrentDomain.GetAssemblies(); foreach (var assembly in assemblies) { Console.WriteLine(assembly.GetName()); } } Now let's look at the first scenario where I have class method that references internally uses System.Web. In the first scenario lets add a method to my main program like this: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); PrintAssemblies(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } UpdateFromWebRequest() internally accesses HttpContext.Current to read some information of the ASP.NET Request object so it clearly needs a reference System.Web to work. In this first example, the method that holds the calling code is never called, but exists as a static method that can potentially be called externally at some point. What do you think will happen here with the assembly loading? Will System.Web load in this example? No - it doesn't. Because the WebLogEntry() method is never called by the mainline application (or anywhere else) System.Web is not loaded. .NET dynamically loads assemblies as code that needs it is called. No code references the WebLogEntry() method and so System.Web is never loaded. Next, let's add the call to this method, which should trigger System.Web to be loaded because a dependency exists. Let's change the code to: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.WriteLine("--- Before:"); PrintAssemblies(); WebLogEntry(); Console.WriteLine("--- After:"); PrintAssemblies(); Console.ReadLine(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } Looking at the code now, when do you think System.Web will be loaded? Will the before list include it? Yup System.Web gets loaded, but only after it's actually referenced. In fact, just until before the call to UpdateFromRequest() System.Web is not loaded - it only loads when the method is actually called and requires the reference in the executing code. Moral of the Story So what have we learned - or maybe remembered again? Dependent Assembly References are not pre-loaded when an application starts (by default) Dependent Assemblies that are not referenced by executing code are never loaded Dependent Assemblies are just in time loaded when first referenced in code All of this is nothing new - .NET has always worked like this. But it's good to have a refresher now and then and go through the exercise of seeing it work in action. It's not one of those things we think about everyday, and as I found out last week, I couldn't remember exactly how it worked since it's been so long since I've learned about this. And apparently I'm not the only one as several other people I had discussions with in relation to loaded assemblies also didn't recall exactly what should happen or assumed incorrectly that just having a reference automatically loads the assembly. The moral of the story for me is: Trying at all costs to eliminate an assembly reference from a component is not quite as important as it's often made out to be. For example, the Westwind.Utilities module described above has a logging component, including a Web specific logging entry that supports pulling information from the active HTTP Context. Adding that feature requires a reference to System.Web. Should I worry about this in the scope of this library? Probably not, because if I don't use that one class of nearly a hundred, System.Web never gets pulled into the parent process. IOW, System.Web only loads when I use that specific feature and if I am, well I clearly have to be running in a Web environment anyway to use it realistically. The alternative would be considerably uglier: Pulling out the WebLogEntry class and sticking it into another assembly and breaking up the logging code. In this case - definitely not worth it. So, .NET definitely goes through some pretty nifty optimizations to ensure that it loads only what it needs and in most cases you can just rely on .NET to do the right thing. Sometimes though assembly loading can go wrong (especially when signed and versioned local assemblies are involved), but that's subject for a whole other post…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • So i ran sudo apt-get install kubuntu-full on my Ubuntu... and saw all the apps...now I want it off...help?

    - by Alex Poulos
    I'm running 12.04 - I installed kubuntu to try it out and realized that with all the bloatware applications that I didn't want it anymore - I was able to uninstall the kubuntu-desktop but there are still packages left over... How can I make sure I get rid of EVERYTHING Kubuntu installed - even the kde leftovers? Here's some of what's left when I ran sudo apt-get autoremove kde then "tab" it displayed this: kdeaccessibility kdepim-runtime kdeadmin kde-runtime kde-baseapps kde-runtime-data kde-baseapps-bin kdesdk-dolphin-plugins kde-baseapps-data kde-style-oxygen kde-config-cron kdesudo kde-config-gtk kdeutils kde-config-touchpad kde-wallpapers kdegames-card-data kde-wallpapers-default kdegames-card-data-extra kde-window-manager kde-icons-mono kde-window-manager-common kdelibs5-data kde-workspace kdelibs5-plugins kde-workspace-bin kdelibs-bin kde-workspace-data kdemultimedia-kio-plugins kde-workspace-data-extras kdenetwork kde-workspace-kgreet-plugins kdenetwork-filesharing kde-zeroconf kdepasswd kdf kdepim-kresources kdm kdepimlibs-kio-plugins kdoctools Those are all installed by kubuntu... correct? I just want to go back to my Ubuntu 12.04LTS with Gnome2-classic and without all the kubuntu extras. I started it off by just removing unnecessary apps that came with kubuntu-full - then realized I didnt want the whole thing at all and uninstalled kubuntu-full but it still says I have these as well: alex@griever:~$ sudo apt-get --purge remove kubuntu- kubuntu-debug-installer kubuntu-netbook-default-settings kubuntu-default-settings kubuntu-notification-helper kubuntu-firefox-installer kubuntu-web-shortcuts

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  • Nice take on Open Source

    - by EmbeddedInsider
    I just revisited the “Micro Framework”- Microsoft’s bootable runtime, essentially an OS that allows managed code to run on small 32bit CPUs, even without Memory Management.  Things are happening http://msdn.microsoft.com/en-us/netframework/bb267253.aspx Abstract The Microsoft .NET Micro Framework is a bootable runtime module that brings the advantages of .NET programming to devices too resource-constrained to run other Microsoft embedded platforms. The benefits of developing with the .NET Micro Framework include the C# programming language, a managed execution environment, a substantial subset of the .NET libraries, and Visual Studio™ deployment and debugging. In this white paper we explain why the .NET Micro Framework is an ideal choice for embedded development and provide technical details of the platform’s Hardware Abstraction Layer (HAL) and Common Language Runtime (CLR). “Micro Framework” is an interesting product, it is very low cost, like zero. And it is largely community controlled under the Apache License.  A partner network is building, and the application environment is .NET. I have been following this for some time, and the community open source approach seems to be working.  There are new features/packages emerging, for example an F# programming language (ARGH! I am still wresting with VB and C#). Anyway, what I found most interesting was a port to Tron.  Tron is a very popular Japanese open source intuitive.  It is a very real time, very compact kernel, and is, like the Micro Framework, ‘free as beer’.  One limit on MF was it was not real time.  But the merger with Tron may eliminate that problem.  Certainly, if I were dealing with a consumer product with quantities in the millions (like a SmartGrid device, or a toy) I would seriously consider something out of this technology pool.

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  • Extension Methods in Dot Net 2.0

    - by Tom Hines
    Not that anyone would still need this, but in case you have a situation where the code MUST be .NET 2.0 compliant and you want to use a cool feature like Extension methods, there is a way.  I saw this article when looking for ways to create extension methods in C++, C# and VB:  http://msdn.microsoft.com/en-us/magazine/cc163317.aspx The author shows a simple  way to declare/define the ExtensionAttribute so it's available to 2.0 .NET code. Please read the article to learn about the when and why and use the content below to learn HOW. In the next post, I'll demonstrate cross-language calling of extension methods. Here is a version of it in C# First, here's the project showing there's no VOODOO included: using System; namespace System.Runtime.CompilerServices {    [       AttributeUsage(          AttributeTargets.Assembly          | AttributeTargets.Class          | AttributeTargets.Method,       AllowMultiple = false, Inherited = false)    ]    class ExtensionAttribute : Attribute{} } namespace TestTwoDotExtensions {    public static class Program    {       public static void DoThingCS(this string str)       {          Console.WriteLine("2.0\t{0:G}\t2.0", str);       }       static void Main(string[] args)       {          "asdf".DoThingCS();       }    } }   Here is the C++ version: // TestTwoDotExtensions_CPP.h #pragma once using namespace System; namespace System {        namespace Runtime {               namespace CompilerServices {               [                      AttributeUsage(                            AttributeTargets::Assembly                             | AttributeTargets::Class                            | AttributeTargets::Method,                      AllowMultiple = false, Inherited = false)               ]               public ref class ExtensionAttribute : Attribute{};               }        } } using namespace System::Runtime::CompilerServices; namespace TestTwoDotExtensions_CPP { public ref class CTestTwoDotExtensions_CPP {    public:            [ExtensionAttribute] // or [Extension]            static void DoThingCPP(String^ str)    {       Console::WriteLine("2.0\t{0:G}\t2.0", str);    } }; }

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