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This causes a compile-time exception:
public sealed class ValidatesAttribute<T> : Attribute { } [Validates<string>] public static class StringValidation { } I realize C# does not support generic attributes. However, after much Googling, I can't seem to find the reason.
Does anyone know why generic types cannot derive from Attribute? Any theories?
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In C programming language, %d and %i are format specifiers as where %d specifies the type of variable as decimal and %i specifies the type as integer. In usage terms, there is no difference in printf() function output while printing a number using %d or %i but using scanf the difference occurs.
Semicolons are end statements in C. The Semicolon tells that the current statement has been terminated and other statements following are new statements. Usage of Semicolon in C will remove ambiguity and confusion while looking at the code.
It was mainly developed as a system programming language to write an operating system. The main features of the C language include low-level memory access, a simple set of keywords, and a clean style, these features make C language suitable for system programmings like an operating system or compiler development.
Logical OR operator: || The logical OR operator ( || ) returns the boolean value true if either or both operands is true and returns false otherwise.
Well, I can't answer why it's not available, but I can confirm that it's not a CLI issue. The CLI spec doesn't mention it (as far as I can see) and if you use IL directly you can create a generic attribute. The part of the C# 3 spec that bans it - section 10.1.4 "Class base specification" doesn't give any justification.
The annotated ECMA C# 2 spec doesn't give any helpful information either, although it does provide an example of what's not allowed.
My copy of the annotated C# 3 spec should arrive tomorrow... I'll see if that gives any more information. Anyway, it's definitely a language decision rather than a runtime one.
EDIT: Answer from Eric Lippert (paraphrased): no particular reason, except to avoid complexity in both the language and compiler for a use case which doesn't add much value.
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