Fix error with ByRow on import

src/parsing.jl

@@ -21,7 +21,7 @@ returns `nothing`.
 get_column_expr(x) = nothing
 function get_column_expr(e::Expr)
     e.head == :$ && return e.args[1]
-    onearg(e, :AsTable) && return e
+    onearg(e, :AsTable) && return :($AsTable($(e.args[2])))
     if onearg(e, :cols)
         Base.depwarn("cols is deprecated use $DOLLAR to escape column names instead", :cols)
         return e.args[2]
@@ -295,9 +295,9 @@ function get_source_fun(function_expr; exprflags = deepcopy(DEFAULT_FLAGS))
 
     if exprflags[BYROW_SYM][]
         if exprflags[PASSMISSING_SYM][]
-            fun = :(ByRow(Missings.passmissing($fun)))
+            fun = :($ByRow($(Missings.passmissing)($fun)))
         else
-            fun = :(ByRow($fun))
+            fun = :($ByRow($fun))
         end
     end
 
@@ -350,7 +350,7 @@ function fun_to_vec(ex::Expr;
     if final_flags[ASTABLE_SYM][]
         src, fun = get_source_fun_astable(ex; exprflags = final_flags)
 
-        return :($src => $fun => AsTable)
+        return :($src => $fun => $AsTable)
     end
 
     if no_dest # subset and with

src/parsing_astable.jl

@@ -100,7 +100,7 @@ function get_source_fun_astable(ex; exprflags = deepcopy(DEFAULT_FLAGS))
     # and if-so, making a named tuple with
     # missing values
     if exprflags[BYROW_SYM][]
-        fun = :(ByRow($fun))
+        fun = :($ByRow($fun))
     end
 
     return source, fun

test/import.jl

@@ -0,0 +1,34 @@
+module TestImport
+
+using Test
+import DataFrames
+import DataFramesMeta
+
+@testset "importing error" begin
+    df = DataFrames.DataFrame(a = [1, 2, 3])
+    t = DataFramesMeta.@rsubset df :a > 1
+    @test t == DataFrames.DataFrame(a = [2, 3])
+    t = DataFramesMeta.@transform df begin
+        @byrow :z = :a == 2
+    end
+    @test t == DataFrames.DataFrame(a = [1, 2, 3], z = [false, true, false])
+
+    t = DataFramesMeta.@rtransform df @astable begin
+        :b = 1
+        :c = 2
+    end
+    @test t == DataFrames.DataFrame(a = [1, 2, 3], b = [1, 1, 1], c  = [2, 2, 2])
+
+    # AsTable on the RHS relies on the literal "AsTable" appearing
+    t = DataFramesMeta.@rtransform df :c = sum(AsTable([:a]))
+    @test t == DataFrames.DataFrame(a = [1, 2, 3], c = [1, 2, 3])
+
+    # And confusingly, if you use DataFrames.AsTable on the RHS, none of the
+    # special escaping happens.
+    # There is not a lot to do about this, unfortunately. I don't want
+    # to modify user-code.
+    @test_throws ArgumentError DataFramesMeta.@transform df :c = sum(DataFrames.AsTable([:a]))
+end
+
+
+end # module