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From Dangling Pointer <danglingpoin...@outlook.com>
Subject Re: String Equality Comparison, Broken Tests and .NET-1.x
Date Fri, 26 Aug 2016 06:49:03 GMT
For this particular case, I think we don't need to specialize code for various versions; just
using the least common denominator and ToUpperInvariantEmptyIfNull method without those diabolical
#ifdefs would suffice.


We can even provide this custom ToUpperEmptyIfNull as string extension method because it is
a language feature and framework version doesn't matter: <LangVersion>6</LangVersion>
in csproj, then:


internal static string ToUpperInvariantEmptyIfNull (this string input)

{

    return input?.ToUpper(CultureInfo.InvariantCulture) ?? string.Empty;

}


Usage strA.ToUpperInvariantEmptyIfNull() == strB.ToUpperInvariantEmptyIfNull()


This only requires the build machine to have Roslyn installed to compile C#6 against whatever
version of framework (even .NET1.1).



________________________________
From: Dominik Psenner <dpsenner@gmail.com>
Sent: Friday, August 26, 2016 5:38:37 AM
To: Log4NET Dev
Subject: Re: String Equality Comparison, Broken Tests and .NET-1.x


On 26 Aug 2016 12:36 a.m., "Dangling Pointer" <danglingpointer@outlook.com<mailto:danglingpointer@outlook.com>>
wrote:
>
> Dominik, looks good. I just quickly typed that code in email compose box. Your changes
are good enough to get incorporated in code base and to conclude this issue IMO.
>
>
> Agree that the more backward compatible the better. I just raised the point that if less
than 1% of log4net consumers are on net2.0 and lower, then they most probably are not updating
their code or dependency packages to the latest versions either. So basically it's just like
you said that the newer version may just focus on mainstream audience; net35 and higher.
>
>
> > You would not throw away a good 25 year old rum either, would you? :-)
>
>
> I wouldn't dare. :)
>
> But by analogy if it is C lib, I would just comply with C99 and C11 ISO standard and
would care less about C89, POSIX'ism etc.

Comparing C with .net these standards, the difference is that the langiage is still mostly
the same but other concepts and the API seamlessly evolves. Choosing a .net framework version
is a choice that can be rethought while the project evolves.

The thing I do not like about the log4net codebase is the preprocessor stuff. It makes reading
and understanding the code almost impossible. Lately I had the vision to rip apart log4net
into several projects where the specialties of the .net frameworks are handled with overrides/implementation
of common interfaces. But this wont be possible realize with the current manpower.

>
> ________________________________
> From: Dominik Psenner <dpsenner@gmail.com<mailto:dpsenner@gmail.com>>
> Sent: Thursday, August 25, 2016 7:52:37 PM
>
> To: Log4NET Dev
> Subject: Re: String Equality Comparison, Broken Tests and .NET-1.x
>
> At first glance this will not compile:
>
> public static bool NeutralizeString(string input)
> {
>     return string.IsNullOrEmpty(input) &&
>                 input.ToUpper(CultureInfo.InvariantCulture);
> }
>
> Further, the name of the method does not fit yet the purpose of the code. Last but not
least, I would advise to make it internal.
>
> internal static string GetStringOrEmptyIfNull(string input)
>   if (string.IsNullOrEmpty(input))
>     return input.ToUpper(CultureInfo.InvariantCulture;
>   else
>     return string.Empty;
>
> > PS - awesome that log4net has thus far maintain the compatibility with .NET1.1!
but are there still consumers of .NET1.1?
>
> There has been a discussion about this some time ago. Please check the mailing list backlog.
The outcome was that we are stopping to maintain everything that is older than .NET 3.5 (exclusive).
If someone wants to have it, he must A) compile it from source and B) fix the source if it
does no longer compile. If the effort is cheap, we will however try to keep it compatible
because of reasons. Maybe we are just old guys that like good old stuff. You would not throw
away a good 25 year old rum either, would you? :-)
>
> 2016-08-25 18:59 GMT+02:00 Dangling Pointer <danglingpointer@outlook.com<mailto:danglingpointer@outlook.com>>:
>>
>> > Unfortunately, this doesn't work if `a` is allowed to be null.
>>
>>
>> I made this change in https://github.com/apache/log4net/pull/30. I think we can use:
>>
>> trimmedTargetName?.ToUpperInvariant()
>>
>> in C#6 syntax or the older syntax:
>>
>> string.IsNullOrEmpty(trimmedTargetName) && trimmedTargetName.ToUpperInvariant()
>>
>> to fix this problem.
>>
>>
>> For .NET 1.1 compatibility, we can just use,
>>
>> string.IsNullOrEmpty(trimmedTargetName) && trimmedTargetName.ToUpper(CultureInfo.InvariantCulture);
>> everywhere without branching out with preprocessor directives.
>>
>> Or maybe a helper method:
>>
>> public static bool NeutralizeString(string input)
>> {
>>     return string.IsNullOrEmpty(input) &&
>>                 input.ToUpper(CultureInfo.InvariantCulture);
>> }
>>
>> Then use NeutralizeString(strA) == NeutralizeString(strB) without specializing for
various versions of framework.
>>
>> PS - awesome that log4net has thus far maintain the compatibility with .NET1.1! but
are there still consumers of .NET1.1? Why would they care to update the NuGet package, the
next version of log4net, when they don't have time to upgrade their project to newer version
of the framework.. just a thought.. :p
>>
>> ________________________________
>> From: Jonas.Baehr@rohde-schwarz.com<mailto:Jonas.Baehr@rohde-schwarz.com> <Jonas.Baehr@rohde-schwarz.com<mailto:Jonas.Baehr@rohde-schwarz.com>>
>> Sent: Tuesday, August 23, 2016 1:50:29 PM
>> To: Log4NET Dev
>> Subject: Re: String Equality Comparison, Broken Tests and .NET-1.x
>>
>> Stefan Bodewig <bodewig@apache.org<mailto:bodewig@apache.org>> wrote
on 23.08.2016 06:14:32:
>>
>> > Von: Stefan Bodewig <bodewig@apache.org<mailto:bodewig@apache.org>>
>> > An: "Log4Net Developers List" <log4net-dev@logging.apache.org<mailto:log4net-dev@logging.apache.org>>
>> > Datum: 23.08.2016 06:14
>> > Betreff: Re: String Equality Comparison, Broken Tests and .NET-1.x
>> >
>> > On 2016-08-22, <Jonas.Baehr@rohde-schwarz.com<mailto:Jonas.Baehr@rohde-schwarz.com>>
wrote:
>> >
>> > > A recent commit [1] changed, among other things, some string equality
>> > > comparisons from `SomeComparer.Compare(a, "B", IgnoreCase) == 0` to
>> > > `a.ToUpperInvariant() == "B"`, see also [2].
>> > >
>> > > Unfortunately, this doesn't work if `a` is allowed to be null. Currently
a
>> > > lot of log4net.Tests are broken because of such a null reference exception
>> > > in `NewLinePatternConverter.ActivateOptions` (apparently "%newline" is
>> > > quite common in pattern layouts ;-).
>> >
>> > Oh, I'm sorry. I must admit I glanced over the PR and applied it without
>> > running the tests. My fault.
>> >
>> > > For new code I tend to opt for `String.Equals(Option, "DOS",
>> > > StringComparison.OrdinalIgnoreCase)` for a fast, case-insensitive
>> > > comparison with fixed ASCII-only patterns, but static
>> > > `String.Equals(String, String, StringComparison)` is not awailable on
>> > > .NET-1.x [3].
>> >
>> > This is what the original code before PR #16 looked like, but it doesn't
>> > seem to be available for .NET Core, see the discussion around
>> > https://github.com/apache/log4net/pull/16/
>> > files#diff-51624ab11a9b3d95cc770de1a4e1bdbc
>>
>> Note quite, it used `string.compare(string, string, bool, CultireInfo) == 0` which
is available on .NET-1.x, while `String.Equals(string, string StringComparison)` and `ToUpperInvariant`
are not.
>>
>> > > Should we create some helper in SystemInfo that provides null-aware,
>> > > ordinal, casing-agnostic string equality comparison, with some #if's
>> > > .NET-1.x?
>> >
>> > +1
>>
>> Here you go. The attached patch introduces a `SystemInfo.EqualsIgnoringCase(string,
string)`, some unit tests, and fixes `NewLinePatternConverter.ActivateOptions` so that the
test suite passes again.
>>
>> Please note that I was only able to test with .NET-4.5.2. I have no .NET-1x around,
nor .NET Core (maybe we can even drop this #elif). I used the code for these platforms from
previous revisions of NewLinePatternConverter.cs. In addition, I'm not sure if I got all the
defines for the #if right. Is there some doc for that?
>>
>> regards,
>> Jonas
>>
>
>
>
> --
> Dominik Psenner

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