Added: LDM Notes for July 27th, 2020

[333fred]

https://github.com/dotnet/csharplang/blob/master/meetings/2020/LDM-2020-07-27.md

Agenda:

• Improved nullable analysis in constructors
• Equality operators (== and !=) in records
• .ToString() or GetDebuggerDisplay() on records?
• Restore W-warning to T t = default; for generic T, now you can write T??

[huoyaoyuan]

Improved nullable analysis in constructors

Happy to see that change. I've ran into this:

foreach (var (key, value) in parameters)
{
    if (key == "name")
        Name = value;
}

if (Name is null) throw new Exception("No name in parameters!");

I had to assign the value to a variable inside loop, and assign it to the property after null check in the non-branch route.

Equality operators (== and !=) in records

In practice, a big advantage of == operators is taking care of null... Writing EqualityComparer.Default<T>.Equals is annoying.

ToString or DebuggerDisplay on record types

Anonymous types use { Prop = value } format. Please consider consistency.

Restore W-warning to T t = default; for generic T, now you can write T?

I wonder the future with non-defaultable value types. It's quite a mess around T? now, and I don't want things to be worse then.
Can the T! syntax that's proposed in very early phase of NRT help?

[erik-kallen]

Nice to see that you are considering improvements to nullable analysis in constructors, but the problem I mentioned in #2830 seems to still be unadressed.

[MgSam]

Very glad to see the == question has a final decision.

[333fred]

Nice to see that you are considering improvements to nullable analysis in constructors, but the problem I mentioned in #2830 seems to still be unadressed.

We're looking at required properties to solve nullable initialization issues.

[erik-kallen]

@333fred Great to hear that you are working on it! I would really like to enable nullable in my web projects, but until we have a solution for that problem it is not worth it IMO.