C# (.NET) Design Flaws [closed]

Answer 1

1. I'm not a big fan of the Stream, StringWriter, StringReader, TextReader, TextWriter classes...it's just not intuitive what is what.
2. IEnumerable.Reset throwing an exception for iterators. I have some third party components which always call reset when databound, requires me to cast to a list first to use these.
3. Xml Serializer should have serialized IDictionary elements
4. I totally forgot about the HttpWebRequest & FTP API what a pain in my....(thanks for the comment Nicholas to remind me of this:-)

Edit
5. Another annoyance of mine is how System.Reflection.BindingFlags, has different uses depending on the method your using. In FindFields for example what does CreateInstance or SetField mean? This is a case where they have overloaded the meaning behind this enumeration which is confusing.

Answer 2

I don't know that I'd go as far as to say it's a design flaw, but it would be really nice if you could infer a lambda expression in the same way you can in VB:

VB:

Dim a = Function(x) x * (x - 1)

C#

It would be nice if could do this:

var a = x => x * (x - 1);

Instead of having to do this:

Func<int, int> a = x => x * (x - 1);

I realise it's not much longer, but in Code Golf every character counts damnit! Don't they take that into account when they design these programming languages? :)

Answer 3

Don't like it that you can't use the values of one enum in another enum, for example:

    enum Colors { white, blue, green, red, black, yellow }

    enum SpecialColors { Colors.blue, Colors.red, Colors.Yellow } 

Answer 4

To add to the long list of good points made by others already:

• DateTime.Now == DateTime.Now in most, but not all cases.

• String which is immutable has a bunch of options for construction and manipulation, but StringBuilder (which is mutable) doesn't.

• Monitor.Enter and Monitor.Exit should have been instance methods, so instead of newing a specific object for locking, you could new a Monitor and lock on that.

• Destructors should never have been named destructors. The ECMA spec calls them finalizers, which is much less confusing for the C++ crowd, but the language specification still refers to them as destructors.

Answer 5

I agree emphatically with this post (for those poo-pooing the lack of ToString, there is a debugger attribute to provide a custom format for your class).

On top of the above list, I would also add the following reasonable requests:

1. non-nullable reference types as a complement to nullable value types,
2. allow overriding a struct's empty constructor,
3. allow generic type constraints to specify sealed classes,
4. I agree with another poster here that requested arbitrary constructor signatures when used as constraints, ie. where T : new(string), or where T : new(string, int)
5. I also agree with another poster here about fixing events, both for empty event lists and in the concurrent setting (though the latter is tricky),
6. operators should be defined as extension methods, and not as static methods of the class (or not just as static methods at least),
7. allow static properties and methods for interfaces (Java has this, but C# does not),
8. allow event initialization in object initializers (only fields and properties are currently allowed),
9. why is the "object initializer" syntax only usable when creating an object? Why not make it available at any time, ie. var e = new Foo(); e { Bar = baz };
10. fix quadratic enumerable behaviour,
11. all collections should have immutable snapshots for iteration (ie. mutating the collection should not invalidate the iterator),
12. tuples are easy to add, but an efficient closed algebraic type like "Either<T>" is not, so I'd love some way to declare a closed algebraic type and enforce exhaustive pattern matching on it (basically first-class support for the visitor pattern, but far more efficient); so just take enums, extend them with exhaustive pattern matching support, and don't allow invalid cases,
13. I'd love support for pattern matching in general, but at the very least for object type testing; I also kinda like the switch syntax proposed in another post here,
14. I agree with another post that the System.IO classes, like Stream, are somewhat poorly designed; any interface that requires some implementations to throw NotSupportedException is a bad design,
15. IList should be much simpler than it is; in fact, this may be true for many of the concrete collection interfaces, like ICollection,
16. too many methods throw exceptions, like IDictionary for instance,
17. I would prefer a form of checked exceptions better than that available in Java (see the research on type and effect systems for how this can be done),
18. fix various annoying corner cases in generic method overload resolution; for instance, try providing two overloaded extension methods, one that operates on reference types, and the other on nullable struct types, and see how your type inference likes that,
19. provide a way to safely reflect on field and member names for interfaces like INotifyPropertyChanged, that take the field name as a string; you can do this by using an extension method that takes a lambda with a MemberExpression, ie. () => Foo, but that's not very efficient,
    • Update: C# 6.0 added the nameof() operator for single member names, but it doesn't work in generics (nameof(T) == "T" instead of the actual type-argument's name: you still need to do typeof(T).Name)) - nor does it allow you to get a "path" string, e.g. nameof(this.ComplexProperty.Value) == "Value" limiting its possible applications.
20. allow operators in interfaces, and make all core number types implement IArithmetic; other useful shared operator interfaces are possible as well,
21. make it harder to mutate object fields/properties, or at the very least, allow annotating immutable fields and make the type checker enforce it (just treat it as getter-only property fer chrissakes, it's not hard!); in fact, unify fields and properties in a more sensible way since there's no point in having both; C# 3.0's automatic properties are a first step in this direction, but they don't go far enough,
    • Update: While C# had the readonly keyword, and C# 6.0 added read-only auto-properties, though it isn't as stringent as true language support for immutable types and values.
22. simplify declaring constructors; I like F#'s approach, but the other post here that requires simply "new" instead of the class name is better at least,

That's enough for now I suppose. These are all irritations I've run into in the past week. I could probably go on for hours if I really put my mind to it. C# 4.0 is already adding named, optional and default arguments, which I emphatically approve of.

Now for one unreasonable request:

1. it'd be really, really nice if C#/CLR could support type constructor polymorphism, ie. generics over generics,

Pretty please? :-)

Answer 6

The awful (and quite invisible to most people) O(N^2) behaviour of nested/recursive iterators.

I'm quite gutted that they know about it, know how to fix it but it is not viewed as having sufficient priority to merit inclusion.

I work with tree like structures all the time and have to correct otherwise smart people's code when they inadvertently introduce highly expensive operations in this way.

The beauty of "yield foreach' is that the simpler, easier syntax encourages correct, performant code. This is the "pit of success" that I think they should aspire to before adding new features for long term success of the platform.