Allow more inputs for gens(::UniversalPolyRing, ...)

src/AbsMSeries.jl

@@ -215,3 +215,7 @@ when it was created.
 function rand(S::MSeriesRing, term_range, v...)
    rand(GLOBAL_RNG, S, term_range, v...)
 end
+
+@varnames_interface Generic.power_series_ring(R::Ring, prec::Int, s)
+@varnames_interface Generic.power_series_ring(R::Ring, weights::Vector{Int}, prec::Int, s) macros=:no # use keyword `weights=...` instead
+@varnames_interface Generic.power_series_ring(R::Ring, prec::Vector{Int}, s) n=:no macros=:no # `n` variant would clash with line above; macro would be the same as for `prec::Int`    

src/AbstractAlgebra.jl

@@ -185,6 +185,7 @@ const FieldElement = Union{FieldElem, Rational, AbstractFloat}
 ###############################################################################
 
 include("fundamental_interface.jl")
+include("misc/VarNames.jl")
 
 ################################################################################
 #
@@ -344,7 +345,6 @@ end
 
 include("misc/ProductIterator.jl")
 include("misc/Evaluate.jl")
-include("misc/VarNames.jl")
 
 ###############################################################################
 #

src/FreeAssociativeAlgebra.jl

@@ -254,3 +254,5 @@ end
 function rand(S::FreeAssociativeAlgebra, term_range, exp_bound, v...)
    rand(GLOBAL_RNG, S, term_range, exp_bound, v...)
 end
+
+@varnames_interface Generic.free_associative_algebra(R::Ring, s)

src/LaurentMPoly.jl

@@ -158,3 +158,5 @@ For information about the many ways to specify `varnames...` refer to [`polynomi
 specification in [`AbstractAlgebra.@varnames_interface`](@ref).
 """
 laurent_polynomial_ring(R::Ring, s::Vector{Symbol})
+
+@varnames_interface Generic.laurent_polynomial_ring(R::Ring, s)

src/MPoly.jl

@@ -1428,6 +1428,8 @@ function polynomial_ring(R::Ring, s::Vector{Symbol}; kw...)
    (S, gens(S))
 end
 
+@varnames_interface polynomial_ring(R::Ring, s)
+
 """
     polynomial_ring(R::Ring, varnames...; cached=true, internal_ordering=:lex)
     polynomial_ring(R::Ring, varnames::Tuple; cached=true, internal_ordering=:lex)

src/RationalFunctionField.jl

@@ -13,3 +13,5 @@
 function rational_function_field(k::Field, s::VarName; cached::Bool=true)
    return Generic.rational_function_field(k, Symbol(s); cached=cached)
 end
+
+@varnames_interface Generic.rational_function_field(K::Field, s)

src/generic/UnivPoly.jl

@@ -254,7 +254,10 @@ function gen(S::UniversalPolyRing{T}, s::VarName) where {T <: RingElement}
    return UnivPoly{T}(gen(mpoly_ring(S), i), S)
 end
 
-gens(S::UniversalPolyRing, v::Vector{<:VarName}) = tuple([gen(S, s) for s in v]...)
+# @varnames_interface expects the 
+gens(S::UniversalPolyRing, varnames...) = _gens(S, varnames...)[2:end]
+_gens(S::UniversalPolyRing, v::Vector{Symbol}) = nothing, [gen(S, s) for s in v]
+@varnames_interface _gens(S::UniversalPolyRing, s)
 
 function gen(S::UniversalPolyRing{T}, i::Int) where {T}
    @boundscheck 1 <= i <= nvars(S) || throw(ArgumentError("generator index out of range"))

src/generic/imports.jl

@@ -75,6 +75,7 @@ import ..AbstractAlgebra: @attributes
 import ..AbstractAlgebra: @enable_all_show_via_expressify
 import ..AbstractAlgebra: @show_name
 import ..AbstractAlgebra: @show_special
+import ..AbstractAlgebra: @varnames_interface
 import ..AbstractAlgebra: CacheDictType
 import ..AbstractAlgebra: CycleDec
 import ..AbstractAlgebra: Dedent

src/misc/VarNames.jl

@@ -474,13 +474,3 @@ macro varnames_interface(e::Expr, options::Expr...)
         $(varnames_macro(d[:f], length(d[:argnames]), opts[:macros], opts[:n], opts[:range]))
     end
 end
-
-@varnames_interface Generic.free_associative_algebra(R::Ring, s)
-@varnames_interface Generic.laurent_polynomial_ring(R::Ring, s)
-@varnames_interface Generic.rational_function_field(K::Field, s)
-
-@varnames_interface Generic.power_series_ring(R::Ring, prec::Int, s)
-@varnames_interface Generic.power_series_ring(R::Ring, weights::Vector{Int}, prec::Int, s) macros=:no # use keyword `weights=...` instead
-@varnames_interface Generic.power_series_ring(R::Ring, prec::Vector{Int}, s) n=:no macros=:no # `n` variant would clash with line above; macro would be the same as for `prec::Int`
-
-@varnames_interface polynomial_ring(R::Ring, s)

test/generic/UnivPoly-test.jl

@@ -323,6 +323,12 @@ end
          @test vars(2x2^2 + 3x2 + 1) == [x]
 
          @test characteristic(S) == 0
+
+         xs, ys = gens(S, :x => (1:4), :y =>(1:2, 1:3))
+         @test xs isa Vector{elem_type(S)}
+         @test length(xs) == 4
+         @test ys isa Matrix{elem_type(S)}
+         @test size(ys) == (2, 3)
       end
    end
 end