Bug 4285 - assigning inline variable in C# style not supported
Summary: assigning inline variable in C# style not supported
Alias: None
Product: iOS
Classification: Xamarin
Component: General ()
Version: 5.2
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2012-04-06 01:08 UTC by duskov
Modified: 2012-04-11 08:05 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description duskov 2012-04-06 01:08:41 UTC
Consider this code (MonoTouch.Dialog classes):
// BEGIN ===========
EntryElement entry1;
RootElement root = new RootElement("Test") {
	new Section () {
		entry1 = new EntryElement("123", "123", null),
// END =============

In C# is possible like this (inline) to initialize "entry1" variable, and then send it's value at the same place. MonoTouch compiler will raise error at that line:
		entry1 = new EntryElement("123", "123", null),

(2) Here are also 2 syntax errors. After closing "Section" class I placed comma on purpose. I also placed comma after closing "EntryElement" constructor's brackets. Since there are no objects defined after those commas, compiler should also report invalid syntax. However, compiler disregards those commas, and no error is shown.
Comment 1 Rolf Bjarne Kvinge [MSFT] 2012-04-11 08:05:17 UTC
(1) The MonoTouch compiler is correct. Try this equivalent code in Visual Studio:

    object entry1;
    var list = new List<object> {
        entry1 = new string ('a', 20),

and you'll get this error:

error CS0117: 'System.Collections.Generic.List<object>' does not contain a definition for 'entry1'

What you need to do is to put parenthesis around the assignment, like this:
        (entry1 = new EntryElement ("123", "123", null)),

(2) The MonoTouch compiler is correct about this too. Try this equivalent in Visual Studio:

    object entry1;
    var list = new List<object> {
        (entry1 = new string ('a', 20)),

In general a trailing comma is allowed when you have a list of items in C#. The same thing is allowed for enums for instance:

enum Foo { one, two, three, }