Why Are Generic Attribute Types Not Allowed in C#?

C#'s Restriction on Generic Attributes: An Unexplained Mystery

Attempting to use generic types within C# attributes results in a baffling compile-time error. For instance:

<code class="language-csharp">[Validates<string>]
public static class StringValidation
{
    // ...
}</code>

This contrasts with languages like Java, where such usage is permitted. C#, however, steadfastly prohibits generic attribute types. The precise reason for this remains unclear.

The ECMA C# 2 and 3 specifications mention this limitation without offering any explanation. A former Microsoft developer and C# language designer, Eric Lippert, suggests that there's no specific, documented rationale. The decision likely stems from a prioritization of language and compiler simplicity, focusing development efforts on features with demonstrably higher value.

Therefore, the prohibition of generic attribute types in C# stands as a noteworthy, and potentially limiting, characteristic of the language, lacking a clear and publicly available justification.

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