Question about UDAs

[Adam D. Ruppe]

On Monday, 3 August 2020 at 03:00:08 UTC, Cecil Ward wrote:
> When practically speaking would you use UDAs? A real-world 
> use-case?

They are useful when you want to attach some kind of metadata to 
the declarations for a library to read. For example, my script.d 
looks for `@scriptable` for methods that it should expose to the 
script user. My cgi.d uses things like `@URLName("foo")` and/or 
`@DisplayName("whatever")` if you want to override the 
auto-wrapper's default strings.

My day job work project uses it for user-visible documentation of 
their functions too, accessible from a command line interface.


> I’ve seen them in use already for core language features 
> instead of keywords like "pure"

i wouldn't call those UDAs because they aren't user-defined... 
but yeah it is the same syntax there basically too.