Unexpected behavior (splatting/symbols)

[bensetterholm]

Cross-post from discourse, at the request of @pdeffebach.

I was trying to find a way to programmatically generate a query by splatting a list of symbols into an @select. I found that the splat ... syntax, (or any objects containing whitespace or hyphens generated with the Symbol function for that matter), generated errors, though passing a variable with a list of symbols of any sort does seem to work.

Example:

using DataFrames

myDict = Dict()
myDict["aKey"] = 1:10
myDict["anotherKey"] = zeros(10)
myDict["a_nice_key"] = rand(Bool, 10)
myDict["a nasty key"] = fill("oof", 10)
df = DataFrame(myDict)

using DataFramesMeta, Lazy

colsOfInterest = [:anotherKey, :a_nice_key]

# Splatting errors, even though went you write out what the splat "evaluates to", it works.
#=
x = @> begin
    df
    @where(:aKey .< 4)
    @select(colsOfInterest...)
end
=#

# This also errors:
#=
x = @> begin
    df
    @where(:aKey .< 4)
    @select(:a_nice_key, Symbol("a nasty key"))
end
=#

# This surprisingly does not error:
pushfirst!(colsOfInterest, Symbol("a nasty key"))
x = @> begin
    df
    @where(:aKey .< 4)
    @select(colsOfInterest)
end

[bkamins]

At some point, when this package is maintained, it should be decided what is best to do in these cases. For the time being here is what you should pass in two of cases that error for you to make them work:

# first error
x = @> begin
    df
    @where(:aKey .< 4)
    @select(colsOfInterest)
end

# second error
x = @> begin
    df
    @where(:aKey .< 4)
    @select(:a_nice_key, :var"a nasty key")
end

[pdeffebach]

Marking this as 1.X because working with multiple columns is important, but non-breaking.

[pdeffebach]

I'm going to close this, since the following works

julia> df = DataFrame(a = [1, 2], b = [3, 4]);
julia> @select(df, $(cols...))
2×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     1      3
   2 │     2      4

julia> @macroexpand(@select(df, $(cols...)))
quote
    #= /home/peterwd/Documents/Development/DataFramesMeta/src/macros.jl:1287 =#
    (DataFrames).select(df, cols...)
end