[Mono-bugs] [Bug 54927][Wis] New - ArrayList::IndexOf does .Equals on the wrong object

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Changed by bmaurer@users.sf.net.

http://bugzilla.ximian.com/show_bug.cgi?id=54927

--- shadow/54927	2004-02-27 08:05:12.000000000 -0500
+++ shadow/54927.tmp.6592	2004-02-27 08:05:12.000000000 -0500
@@ -0,0 +1,125 @@
+Bug#: 54927
+Product: Mono/Class Libraries
+Version: unspecified
+OS: 
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Wishlist
+Component: CORLIB
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: bmaurer@users.sf.net               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: ArrayList::IndexOf does .Equals on the wrong object
+
+As seen on mono-devel-list
+From Tom Shelton <tom@mtogden.com>:
+
+I have a case of some code I wrote using Mono, that doesn't work properly 
+under .NET.  I thought maybe you guys would like to know about it, as it 
+seems to be a difference in implementation of the ArrayList class...
+
+Basically, what I have created is a typed collection class that inherits 
+from 
+System.Collections.CollectionBase.   The type that is stored in this 
+collection has overriden Object.ToEquals to look something like this:
+
+public class Column
+{
+    .....
+
+    public override bool ToEquals(object obj)
+    {
+        if (obj is Column)
+        {
+            return (obj.ToString() == this.ToString());
+        }
+        else if (obj is string)
+        {
+            return ((string) obj == this.ToString());
+        }
+        else
+        {
+            return false;
+        }
+    }
+
+}
+
+In my ColumnCollection class,  I was implementing overloaded versions of 
+the 
+indexer, Contains, IndexOf, Remove, etc. that can take either another 
+Column, 
+or a string.  This works beautifully under Mono...
+
+public class CollumnCollection : System.Collections.CollectionBase
+{
+    ....
+
+    public int IndexOf (Column value)
+    {
+        return this.InnerList.IndexOf(value);
+    }
+
+    public int IndexOf (string value)
+    {
+        return this.InnerList.IndexOf(value);
+    }
+
+    etc...
+}
+
+When, I would do
+ColumnCollection columns = new ColumnCollection();
+
+columns.Add(new Column("TABLE", "FIELD"));
+....
+
+Column col = new Column("TABLE", "FIELD");
+Console.WriteLine(columns.Contains(col));
+Console.WriteLine("TABLE.FIELD");
+
+the output, would be:
+True
+True
+
+This does not work on .NET - what I get is:
+True
+False
+
+In stepping through the code this morning, I found that in .NET my .Equals 
+method is never called.  What I believe (no, I didn't look at the IL - I 
+guess I should of), is that .NET is doing a sequence something like this 
+when 
+you call Contains, IndexOf, etc... (value is the object your looking 
+for...)
+
+foreach (object obj in InnerList)
+{
+    if (value.Equals(obj))
+    {
+        .....
+    }
+}
+
+Where, as Mono seems to be doing something like this (and I think this is 
+the 
+more sensible approach by the way...)
+
+foreach (object obj in InnerList)
+{
+    if (obj.Equals(value))
+    {
+        ....
+    }
+}
+
+I fixed these string methods easily enough - I just did my own loop, 
+rather 
+then delegate to the InnerList.  But, I thought I would point out this 
+simple 
+little inconsistency.