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  • When should I use String.Format or String.Concat instead of the concatenation operator?

    - by Kramii
    In C# it is possible to concatenate strings in several different ways: Using the concatenation operator: var newString = "The answer is '" + value + "'."; Using String.Format: var newString = String.Format("The answer is '{0}'.", value); Using String.Concat: var newString = String.Concat("The answer is '", value, "'."); What are the advantages / disadvantages of each of these methods? When should I prefer one over the others? The question arises because of a debate between developers. One never uses String.Format for concatenation - he argues that this is for formatting strings, not for concatenation, and that is is always unreadable because the items in the string are expressed in the wrong order. The other frequently uses String.Format for concatenation, because he thinks it makes the code easier to read, especially where there are several sets of quotes involved. Both these developers also use the concatenation operator and String.Builder, too.

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  • Is there a problem with this MySQL Query?

    - by ThinkingInBits
    http://pastie.org/954073 The echos at the top all display valid data that fit the database schema. There are no connection errors Any ideas? Thanks in advance! Here is the echo'ed query INSERT INTO equipment (cat_id, name, year, manufacturer, model, price, location, condition, stock_num, information, description, created, modified) VALUES (1, 'r', 1, 'sdf', 'sdf', '2', 'd', 'd', '3', 'asdfasdfdf', 'df', '10 May 10', '10 May 10') MySQL is giving: #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'condition, stock_num, information, description, created, modified) VALUES (1, 'r' at line 1 id int(11) unsigned NO PRI NULL auto_increment Edit Delete cat_id int(11) unsigned NO NULL Edit Delete prod_name varchar(255) YES NULL Edit Delete prod_year varchar(10) YES NULL Edit Delete manufacturer varchar(255) YES NULL Edit Delete model varchar(255) YES NULL Edit Delete price varchar(10) YES NULL Edit Delete location varchar(255) YES NULL Edit Delete condition varchar(25) YES NULL Edit Delete stock_num varchar(128) YES NULL Edit Delete information text YES NULL Edit Delete description text YES NULL Edit Delete created varchar(20) YES NULL Edit Delete modified varchar(20) YES NULL Query: INSERT INTO equipment (cat_id, prod_name, prod_year, manufacturer, model, price, location, condition, stock_num, information, description, created, modified) VALUES (1, 'asdf', '234', 'adf', 'asdf', '34', 'asdf', 'asdf', '234', 'asdf', 'asdf', '10 May 10', '10 May 10')

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  • Why empty String is treated as null in oracle?

    - by GK
    We are using empty string in DB2 database for some business logic. but when the same record tried to insert into the Oracle it throws some not null property references to null value error. that is oracle treats empty string as null. So i am wondering why it is like that. and if there is a requirement of storing empty string how to do that on oracle?

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  • Creating form using Generic_inlineformset_factory from the Model Form

    - by Prateek
    hello dear all, I wanted to create a edit form with the help of ModelForm. and my models contain a Generic relation b/w classes, so if any one could suggest me the view and a bit of template for the purpose I would be very thankful, as I am new to the language. My models look like:- class Employee(Person): nickname = models.CharField(_('nickname'), max_length=25, null=True, blank=True) blood_type = models.CharField(_('blood group'), max_length=3, null=True, blank=True, choices=BLOOD_TYPE_CHOICES) marital_status = models.CharField(_('marital status'), max_length=1, null=True, blank=True, choices=MARITAL_STATUS_CHOICES) nationality = CountryField(_('nationality'), default='IN', null=True, blank=True) about = models.TextField(_('about'), blank=True, null=True) dependent = models.ManyToManyField(Dependent, through='DependentRelationship') pan_card_number = models.CharField(_('PAN card number'), max_length=50, blank=True, null=True) policy_number = models.CharField(_('policy number'), max_length=50, null=True, blank=True) # code specific details user = models.OneToOneField(User, blank=True, null=True, verbose_name=_('user')) class Person(models.Model): """Person model""" title = models.CharField(_('title'), max_length=20, null=True, blank=True) first_name = models.CharField(_('first name'), max_length=100) middle_name = models.CharField(_('middle name'), max_length=100, null=True, blank=True) last_name = models.CharField(_('last name'), max_length=100, null=True, blank=True) suffix = models.CharField(_('suffix'), max_length=20, null=True, blank=True) slug = models.SlugField(_('slug'), max_length=50, unique=True) class PhoneNumber(models.Model) : phone_number = generic.GenericRelation('PhoneNumber') email_address = generic.GenericRelation('EmailAddress') address = generic.GenericRelation('Address') date_of_birth = models.DateField(_('date of birth'), null=True, blank=True) gender = models.CharField(_('gender'), max_length=1, null=True, blank=True, choices=GENDER_CHOICES) content_type = models.ForeignKey(ContentType, If anyone could suggest me a link or so. it would be a great help........

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  • Move constructor and assignment operator: why no default for derived classes?

    - by doublep
    Why there is default move constructor or assignment operator not created for derived classes? To demonstrate what I mean; having this setup code: #include <utility> struct A { A () { } A (A&&) { throw 0; } A& operator= (A&&) { throw 0; } }; struct B : A { }; either of the following lines throws: A x (std::move (A ()); A x; x = A (); but neither of the following does: B x (std::move (B ()); B x; x = B (); In case it matters, I tested with GCC 4.4.

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  • How do I check if a SQL Server 2005 TEXT column is not null or empty using LINQ To Entities?

    - by emzero
    Hi there guys I'm new to LINQ and I'm trying to check whether a TEXT column is null or empty (as String.IsNullOrEmpty). from c in ... ... select new { c.Id, HasBio = !String.IsNullOrEmpty(c.bio) } Trying to use the above query produces an SqlException: Argument data type text is invalid for argument 1 of len function. The SQL generated is similar to the following: CASE WHEN ( NOT (([Extent2].[bio] IS NULL) OR (( CAST(LEN([Extent2].[bio]) AS int)) = 0))) THEN cast(1 as bit) WHEN (([Extent2].[bio] IS NULL) OR (( CAST(LEN([Extent2].[bio]) AS int)) = 0)) THEN cast(0 as bit) END AS [C1] LEN is not applicable to TEXT columns. I know DATALENGTH should be used for them... How can I force LINQ to produce such thing? Or any other workaround to test if a text column is null or empty??? Thanks!

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  • Displaying progressbar using threading in win 32 applicaition!

    - by kiddo
    In my application I have a simple module were I will read files for some process that will take few seconds..so I thought of displaying a progress bar(using worker thread) while the files are in progress.I have created a thread (code shown below) and also I designed a dialog window with progress control.I used the function MyThreadFunction below to display the progressbar but it just shows only one time and disappears,I am not sure how to make it work.I tried my best inspite of the fact that I am new to threading. reading files void ReadMyFiles() { for(int i = 0; i < fileCount ; fileCount++) { CWinThread* myThread = AfxBeginThread((AFX_THREADPROC)MyThreadFunction,NULL); tempState = *(checkState + index); if(tempCheckState == NOCHECKBOX) { //my operations } else//CHECKED or UNCHECKED { //myoperation } myThread->PostThreadMessage(WM_QUIT,NULL,NULL); } } thread functions UINT MyThreadFunction(LPARAM lparam) { HWND dialogWnd = CreateWindowEx(0,WC_DIALOG,L"Proccessing...",WS_OVERLAPPEDWINDOW|WS_VISIBLE, 600,300,280,120,NULL,NULL,NULL,NULL); HWND pBarWnd = CreateWindowEx(NULL,PROGRESS_CLASS,NULL,WS_CHILD|WS_VISIBLE|PBS_MARQUEE,40,20,200,20, dialogWnd,(HMENU)IDD_PROGRESS,NULL,NULL); MSG msg; PostMessage( pBarWnd, PBM_SETRANGE, 0, MAKELPARAM( 0, 100 ) ); PostMessage(pBarWnd,PBM_SETPOS,0,0); while(PeekMessage(&msg,NULL,NULL,NULL,PM_NOREMOVE)) { if(msg.message == WM_QUIT) { DestroyWindow(dialogWnd); return 1; } AfxGetThread()->PumpMessage(); Sleep(40); } return 1; }

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  • How to show the progressbar using threading functionality in win32?

    - by kiddo
    In my application I have a simple module were I will read files for some process that will take few seconds..so I thought of displaying a progress bar(using worker thread) while the files are in progress.I have created a thread (code shown below) and also I designed a dialog window with progress control.I used the function MyThreadFunction below to display the progressbar but it just shows only one time and disappears,I am not sure how to make it work.I tried my best inspite of the fact that I am new to threading.Please help me with this friends. reading files void ReadMyFiles() { for(int i = 0; i < fileCount ; fileCount++) { CWinThread* myThread = AfxBeginThread((AFX_THREADPROC)MyThreadFunction,NULL); tempState = *(checkState + index); if(tempCheckState == NOCHECKBOX) { //my operations } else//CHECKED or UNCHECKED { //myoperation } myThread->PostThreadMessage(WM_QUIT,NULL,NULL); } } thread functions UINT MyThreadFunction(LPARAM lparam) { HWND dialogWnd = CreateWindowEx(0,WC_DIALOG,L"Proccessing...",WS_OVERLAPPEDWINDOW|WS_VISIBLE, 600,300,280,120,NULL,NULL,NULL,NULL); HWND pBarWnd = CreateWindowEx(NULL,PROGRESS_CLASS,NULL,WS_CHILD|WS_VISIBLE|PBS_MARQUEE,40,20,200,20, dialogWnd,(HMENU)IDD_PROGRESS,NULL,NULL); MSG msg; PostMessage( pBarWnd, PBM_SETRANGE, 0, MAKELPARAM( 0, 100 ) ); PostMessage(pBarWnd,PBM_SETPOS,0,0); while(PeekMessage(&msg,NULL,NULL,NULL,PM_NOREMOVE)) { if(msg.message == WM_QUIT) { DestroyWindow(dialogWnd); return 1; } AfxGetThread()->PumpMessage(); Sleep(40); } return 1; }

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  • In Ruby, can the coerce() method know what operator it is that requires the help to coerce?

    - by Jian Lin
    In Ruby, it seems that a lot of coerce() help can be done by def coerce(something) [self, something] end that's is, when 3 + rational is needed, Fixnum 3 doesn't know how to handle adding a Rational, so it asks Rational#coerce for help by calling rational.coerce(3), and this coerce instance method will tell the caller: # I know how to handle rational + something, so I will return you the following: [self, something] # so that now you can invoke + on me, and I will deal with Fixnum to get an answer So what if most operators can use this method, but not when it is (a - b) != (b - a) situation? Can coerce() know which operator it is, and just handle those special cases, while just using the simple [self, something] to handle all the other cases where (a op b) == (b op a) ? (op is the operator).

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  • Django says the "id may not be NULL" but why is it?

    - by Oli
    I'm going crazy today. I just tried to insert a new record and it threw back a "post_blogpost.id may not be NULL" error. Here's my model: class BlogPost(models.Model): title = models.CharField(max_length=100) slug = models.SlugField(max_length=100) who = models.ForeignKey(User, default=1) when = models.DateTimeField() intro = models.TextField(blank=True, null=True) content = models.TextField(blank=True, null=True) counter = models.PositiveIntegerField(default=0) published = models.BooleanField(default=False) css = models.TextField(blank=True, null=True) class Meta: ordering = ('-when', 'id') There are a number of functions beneath the model too but I won't include them in full here. Their names are: content_cache_key, clear_cache, __unicode__, reads, read, processed_content. I'm adding through the admin... And I'm running out of hair.

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  • atk4 advanced crud?

    - by thindery
    I have the following tables: -- ----------------------------------------------------- -- Table `product` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `product` ( `id` INT NOT NULL AUTO_INCREMENT , `productName` VARCHAR(255) NULL , `s7location` VARCHAR(255) NULL , PRIMARY KEY (`id`) ) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `pages` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `pages` ( `id` INT NOT NULL AUTO_INCREMENT , `productID` INT NULL , `pageName` VARCHAR(255) NOT NULL , `isBlank` TINYINT(1) NULL , `pageOrder` INT(11) NULL , `s7page` INT(11) NULL , PRIMARY KEY (`id`) , INDEX `productID` (`productID` ASC) , CONSTRAINT `productID` FOREIGN KEY (`productID` ) REFERENCES `product` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `field` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `field` ( `id` INT NOT NULL AUTO_INCREMENT , `pagesID` INT NULL , `fieldName` VARCHAR(255) NOT NULL , `fieldType` VARCHAR(255) NOT NULL , `fieldDefaultValue` VARCHAR(255) NULL , PRIMARY KEY (`id`) , INDEX `id` (`pagesID` ASC) , CONSTRAINT `pagesID` FOREIGN KEY (`pagesID` ) REFERENCES `pages` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; I have gotten CRUD to work on the 'product' table. //addproduct.php class page_addproduct extends Page { function init(){ parent::init(); $crud=$this->add('CRUD')->setModel('Product'); } } This works. but I need to get it so that when a new product is created it basically allows me to add new rows into the pages and field tables. For example, the products in the tables are a print product(like a greeting card) that has multiple pages to render. Page 1 may have 2 text fields that can be customized, page 2 may have 3 text fields, a slider to define text size, and a drop down list to pick a color, and page 3 may have five text fields that can all be customized. All three pages (and all form elements, 12 in this example) are associated with 1 product. So when I create the product, could i add a button to create a page for that product, then within the page i can add a button to add a new form element field? I'm still somewhat new to this, so my db structure may not be ideal. i'd appreciate any suggestions and feedback! Could someone point me toward some information, tutorials, documentation, ideas, suggestions, on how I can implement this?

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  • Why is the EntityManager in my GAE + Spring (+graniteds) project reset to null?

    - by prefabSOFT
    Hi all, I'm having a problem with autowiring my EntityManager. Actually at server startup I can see that the injection works ok, though when trying to use my EntityManager it appears to be null again. @Component public class DataDaoImpl { protected EntityManager entityManager; @Autowired public void setEntityManager(EntityManager entityManager) { System.out.println("Injecting "+entityManager); //works! this.entityManager = entityManager; } public void createData(String key, String value) { System.out.println("In createData entityManager is "+entityManager); //entityManager null!? ... Output: Injecting org.datanucleus.store.appengine.jpa.DatastoreEntityManager@a60d19 The server is running at http://localhost:8888/ In createData entityManager is null So somehow the autowired entityManager is reset to null when trying to use it. It's a graniteds powered project though I don't think this is graniteds related. Any ideas? Thanks a lot in advance, Jochen

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  • Add not null DateTime column to SQLite without default value?

    - by acidzombie24
    It looks like i cant add a not null constraint or remove a default constraint. I would like to add a datetime column to a table and have all the values set to anything (perhaps 1970 or year 2000) but it seems like i cant use not null without a default and i cant remove a default once added in. So how can i add this column? (once again just a plain datetime not null)

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  • Cant render a .avi file

    - by Manish
    Hi, This is my 3rd post regarding this issue of cropping a file into smaller (same format files) .Please some one help me with this.Here is my code : CoInitialize(NULL); //Create the FGM CoCreateInstance(CLSID_FilterGraph,NULL,CLSCTX_INPROC_SERVER,IID_IGraphBuilder,(void**)(&pGraphBuilder)); //Query the Interfaces pGraphBuilder->QueryInterface(IID_IMediaControl,(void**)&pMediaControl); pGraphBuilder->QueryInterface(IID_IMediaEvent,(void**)&pMediaEvent); pGraphBuilder->QueryInterface(IID_IMediaPosition,(void**)&pMediaPosition); //Adding a Filewriter before calling the renderfile IBaseFilter *pWriter=NULL; IFileSinkFilter *pSink=NULL; CoCreateInstance(CLSID_FileWriter,NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&pWriter)); pWriter->QueryInterface(IID_IFileSinkFilter,(void**)&pSink); pSink->SetFileName(OUTFILE,NULL); //Create a source filter IBaseFilter* pSource=NULL; HRESULT hr11=pGraphBuilder->AddSourceFilter(FILENAME,L"Source",&pSource); //Create a AVI mux IBaseFilter *pAVImux; CoCreateInstance(CLSID_AviDest,NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&pAVImux)); pGraphBuilder->AddFilter(pAVImux,L"AVI Mux"); pGraphBuilder->AddFilter(pWriter,L"File Writer"); //Connect Source and Mux IEnumPins* pEnum1=NULL; IPin* pPin1=NULL; IEnumPins *pEnum2=NULL; IPin *pPin2=NULL; pSource->EnumPins(&pEnum1); pEnum1->Next(1,&pPin1,NULL); HRESULT hr1=ConnectFilters(pGraphBuilder,pPin1,pAVImux); //Mux to Writer HRESULT hr4=ConnectFilters(pGraphBuilder,pAVImux,pWriter); //Render the input file HRESULT hr3=pGraphBuilder->RenderFile(FILENAME,NULL); //Set Display times pMediaPosition->put_CurrentPosition(0); pMediaPosition->put_StopTime(2); //Run the graph HRESULT hr=pMediaControl->Run(); On running no video is shown. All the hresults return S_OK .A .avi file( larger than original is created) and I cannot play that file.

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  • Why aren't operator conversions implicitly called for templated functions? (C++)

    - by John Gordon
    I have the following code: template <class T> struct pointer { operator pointer<const T>() const; }; void f(pointer<const float>); template <typename U> void tf(pointer<const float>); void g() { pointer<float> ptr; f(ptr); tf(ptr); } When I compile the code with gcc 4.3.3 I get a message (aaa.cc:17: error: no matching function for call to ‘tf(pointer<float>&)’) indicating that the compiler called 'operator pointer<const T>' for the non-templated function f(), but didn't for the templated function tf(). Why and is there any workaround short of overloading tf() with a const and non-const version? Thanks in advance for any help.

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  • Entity framework generates values for NOT NULL columns which has default defined in db.

    - by Muhammad Kashif Nadeem
    Hi I have a table Customer. One of the columns in table is DateCreated. This column is NOT NULL but default values is defined for this column in db. When I add new Customer using EF4 from my code. var customer = new Customer(); customer.CustomerName = "Hello"; customer.Email = "[email protected]"; // Watch out commented out. //customer.DateCreated = DateTime.Now; context.AddToCustomers(customer); context.SaveChanges(); Above code generates following query. exec sp_executesql N'insert [dbo].[Customers]([CustomerName], [Email], [Phone], [DateCreated], [DateUpdated]) values (@0, @1, null, @2, null) select [CustomerId] from [dbo].[Customers] where @@ROWCOUNT > 0 and [CustomerId] = scope_identity() ',N'@0 varchar(100),@1 varchar(100),@2 datetime2(7) ',@0='Hello',@1='[email protected]',@2='0001-01-01 00:00:00' And throws following error The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value. The statement has been terminated. Can you please tell me how NOT NULL columns which has default values at db level should not have values generated by EF? DB: DateCreated DATETIME NOT NULL DateCreated Properties in EF: Nullable: False Getter/Setter: public Type: DateTime DefaultValue: None Thanks.

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  • Where would I use a bitwise operator in JavaScript?

    - by J-P
    I've read this (http://stackoverflow.com/quest...), so I know what bitwise operators are but I'm still not clear on how one might use them... Can anyone offer any real-world examples of where a bitwise operator would be useful in JavaScript? Thanks. Edit: Just digging into the jQuery source I've found a couple of places where bitwise operators are used, for example: (only the & operator) // Line 2756: event.which = (event.button & 1 ? 1 : ( event.button & 2 ? 3 : ( event.button & 4 ? 2 : 0 ) )); // Line 2101 var ret = a.compareDocumentPosition(b) & 4 ? -1 : a === b ? 0 : 1;

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  • Can't I send NULL as a parameter with a constructor?

    - by Jason94
    Lets say i have a Shape object that has a constructor like this: Shape( width, height, radius, depth ) Now, I just have a silly rect so i dont need redius and depth... is it okey to do Shape myRect(50, 50, NULL, NULL) ? I know its not the best idea and I should use inheritance and stuff but this is the mess im in so can i use NULL like this?

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  • Is Catching a Null Pointer Exception a Code Smell?

    - by Drew
    Recently a co-worker of mine wrote in some code to catch a null pointer exception around an entire method, and return a single result. I pointed out how there could've been any number of reasons for the null pointer, so we changed it to a defensive check for the one result. However, catching NullPointerException just seemed wrong to me. In my mind, Null pointer exceptions are the result of bad code and not to be an expected exception in the system. Are there any cases where it makes sense to catch a null pointer exception?

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  • Why doesn't HashTable.Contains() just simply return false if it is passed a null?

    - by Nate Pinchot
    I understand why passing a null to HashTable.Contains() doesn't work, but I don't understand what the point of it throwing an ArgumentNullException is - instead of just simply returning false? What is the benefit of throwing the exception (other than to make me do null checks before calling .Contains())? Caused By [System.ArgumentNullException] Key cannot be null. Parameter name: key at System.Collections.Hashtable.ContainsKey(Object key) at System.Collections.Hashtable.Contains(Object key)

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  • Is it possible to pass arithmetic operators to a method in java?

    - by drJames
    Right now I'm going to have to write a method that looks like this: public String Calculate(String Operator, Double Operand1, Double Operand2) { if (Operator.equals("+")) { return String.valueOf(Operand1 + Operand2); } else if (Operator.equals("-")) { return String.valueOf(Operand1 - Operand2); } else if (Operator.equals("*")) { return String.valueOf(Operand1 * Operand2); } else { return "error..."; } } It would be nice if I could write the code more like this: public String Calculate(String Operator, Double Operand1, Double Operand2) { return String.valueOf(Operand1 Operator Operand2); } So Operator would replace the Arithmetic Operators (+, -, *, /...) Does anyone know if something like this is possible in java?

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  • Why can I check some event handlers for null, some not?

    - by Inno
    Hi, I have a ugly piece of code that adds event handlers. The problem is, if the code is called multiple times, the event handlers are called multiple times. To solve the problem, I remove the event handler first and then add it. Now I've seen the following behaviour: Some event handlers can be checked like: if (object.event == null) { // // Code // } others of the form if (object.object.event == null) { // // Code // } I get a message like 'object.object.event' may only occur left of -= or +=. (Since I'm using a german version of visual studio, I don't know the correct translation to english). I have no idea why the behaviour looks this inconsequent so I would be grateful for some information on this. To be more specific: It's user control. if (myControl.Event == null) { // // works // } if (myControl.TreeView.NodeMouseClick == null) { // // doesn't work // }

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