Make [specific type of code] valid code to be used for metaprogramming (useful in e.g. ModelingToolkit and Catalyst DSLs)

[TorkelE]

Would it be possible to make

@parameters begin
    p [description="A parameter"]
    d [description="Another parameter"]
end

valid notation so that it can be used in metaprogramming?

In e.g. ModelingToolkit (https://github.com/SciML/ModelingToolkit.jl) one can declare parameters using

@parameters p d

Next, if one wants to add metadata to a parameter, it is added in a square bracket afterwards:

@parameters p [description="A parameter"] d [description="Another parameter"]

However, if the number of parameters gets long, this gets hard to read. Here, there is a begin ... end form (with one parameter on each line):

@parameters begin
    p
    d
end

However, if we now need to add metadata, this is not possible using the same notation as with a single line, as this:

:(@parameters begin
    p [description="A parameter"] 
    d [description="Another parameter"] 
end)

is not valid Julia notation. Instead, a , is added to make things work:

@parameters begin
    p, [description="A parameter"]
    d, [description="Another parameter"]
end

This is still a bit awkward, as the notation in single-line and multi-line declarations are different. Would it be possible to enable

:(@parameters begin
    p [description="A parameter"] 
    d [description="Another parameter"] 
end)

as permitted for metaprogramming? I read someone asking about new notations for metaprogramming on the Slack, and got a reply that adding stuff like this was possible. If this is the case, I think adding this would be useful to a set of packages with a fairly large user base (and if it is not possible, we can definitely manage without!).

Would this be useful, @ChrisRackauckas?

[bvdmitri]

We use somewhat similar construction with the where block, e.g. this should work fine for you:

@parameters begin
    p where { description="A parameter" }
    d where { description="Another parameter" }
end