[Mono-dev] [PATCH] Add GetString to UnicodeEncoding 2.0 and modifysome Encoding wrappers
kornelpal at gmail.com
Mon Apr 10 07:12:19 EDT 2006
OK, now I understand what you mean.:)
UnicodeEncoding.GetString should have exactly the same result as previously
but it should be much faster because data is written directly to the string
instead of creating a temporary char buffer.
All the modified Encoding methods are very high level wrappers that have
currently faster implementations than in my patch because some unnecessary
checks are avoided.
The problem however is that Encoding is an abstract class with a lot of
virtual methods so people can implement their own encodings. In this case
they may assume that these wrappers call (or wrap) the same methods as in
I noticed this when implementing UnicodeEncoding.GetString because GetString
(byte) calls GetString (byte bytes, int, int) on MS.NET while Mono uses
new string (GetChars (byte)). As you can see on MS.NET overriding
GetString (byte bytes, int, int) will result in modification of GetString
(byte) as well while on Mono you have to override both of them to have the
The same goes for the two other modified Encoding methods. They are higher
level wrappers on MS.NET than on Mono.
So the difference can only be experienced when overriding methods in
Encoding, you will get different results on MS.NET and Mono.
The exact behaviour of these wrappers could be enforced using a test case by
creating an inherited class that throws exceptions when methods that should
not be called are called and fails when the expected method was not called
but I'm not sure whether we need this kind of tests.
Note that explicitly throwing ArgumentNullException is required because of
accessing .Length that would result in NullReferenceException. These methods
throw ArgumentNullException on MS.NET. Previously I thought that
ArgumentNullExceptions were already thrown by the wrapped methods in the
current implementation but now I reallized that GetBytes (char) currently
throws NullReferenceException that is a bug.
So the goal of this patch is to implement a fast UnicodeEncoding.GetString
and to modify some wrapper methods of Encoding to call the same methods as
they do on MS.NET (this actually means to make the higher level wrappers
than they are currently).
----- Original Message -----
From: "Atsushi Eno" <atsushi at ximian.com>
To: "Kornél Pál" <kornelpal at gmail.com>
Cc: <mono-devel-list at lists.ximian.com>
Sent: Monday, April 10, 2006 12:54 PM
Subject: Re: [Mono-dev] [PATCH] Add GetString to UnicodeEncoding 2.0 and
modifysome Encoding wrappers
> Kornél Pál wrote:
>> No, but if you have conceptions regarding what kind of new tests we need
>> I can create some.
> Things that fails without your patch but does not fail with it.
> (Otherwise why did you create the patch? ;-)
> For GetBytes() fix I can imagine the difference (though it is very
> minor: whether it throws NullReferenceException or
> ArgumentNullException) but not sure for others.
> Atsushi Eno
More information about the Mono-devel-list