Bug 33165 - Box Then Cast Defect
Summary: Box Then Cast Defect
Status: RESOLVED ANSWERED
Alias: None
Product: Forms
Classification: Xamarin
Component: Android ()
Version: 1.4.4
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2015-08-17 13:42 UTC by jmeyer
Modified: 2015-08-24 11:06 UTC (History)
2 users (show)

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


Attachments
Sample code reproducing observed issue (32.92 KB, application/x-zip-compressed)
2015-08-17 13:42 UTC, jmeyer
Details


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Status:
RESOLVED ANSWERED

Description jmeyer 2015-08-17 13:42:41 UTC
Created attachment 12535 [details]
Sample code reproducing observed issue

Attempting to cast a value that has been boxed results in the following error message & crashes, even when the cast should be valid: "Cannot cast from source type to destination type"

For example, the following code fragment would produce this error:

            int integer = 5;
            object boxedValue = integer;
            float castedToFloat = (float) boxedValue; //Cast error thrown

Please find attached example which demonstrates this behavior
Comment 1 Brian Bennewitz 2015-08-17 14:35:27 UTC
This is painful inside of IValueConverter implementations where the values come in pre-boxed.
Comment 2 Paul DiPietro [MSFT] 2015-08-24 11:06:32 UTC
Hi all,

This is not actually an issue with Forms and is expected behavior within C# and the compiler. If you attempt to do the same thing within a basic console application you will run into the InvalidCastException. For more information on this you can read this post by Eric Lippert:

http://blogs.msdn.com/b/ericlippert/archive/2009/03/19/representation-and-identity.aspx