You cannot do this, but there’s no rule saying that you have to use the value that comes back. You can simply pass a temporary variable that you never use again. C# 4.0 allows optional parameters, but out parameters can’t be optional. EDIT: BTW, you can also overload the method: int DoStuff() { int temp; … Read more
The callback approach mentioned by @Felix Kling is probably the best idea, but I’ve also found that sometimes it’s easy to leverage Javascript object literal syntax and just have your function return an object on error: function mightFail(param) { // … return didThisFail ? { error: true, msg: “Did not work” } : realResult; } … Read more
You invoke a method with an out parameter via reflection just like any other method. The difference is that the returned value will be copied back into the parameter array so you can access it from the calling function. object[] args = new object[] { address, request }; _DownloadDataInternal.Invoke(this, args); request = (WebRequest)args[1];
You’d have to explicitly use a field and “normal” property instead of an auto-implemented property: public class Bob { private int value; public int Value { get { return value; } set { this.value = value; } } } Then you can pass the field as an out parameter: Int32.TryParse(“123”, out bob.value); But of course, … Read more
No, there is no equivalent of the out keyword in VB. However, VB does automatically initialise all local variables in a method, so you can use ByRef without needing to explicitly initialise the variable first. Example: Sub Main() Dim y As Integer Test(y) End Sub Sub Test(ByRef x As Integer) x = 42 End Sub … Read more
============= UPDATE: I used this answer as the basis for this blog entry: Why do ref and out parameters not allow type variation? See the blog page for more commentary on this issue. Thanks for the great question. ============= Let’s suppose you have classes Animal, Mammal, Reptile, Giraffe, Turtle and Tiger, with the obvious subclassing … Read more