How to add metadata info to a DataFrame?

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Dear all,
this topic has been inactive for a few months, but I just wanted to add that I implemented a package to solve the first problem posted, namely how to add metadata information to a DataFrame.

The trick is to use composition and the ReusePatterns package to automatically forward all method calls from one type to another. The relevant code is:

using ReusePatterns
struct DataFrameMeta <: AbstractDataFrame
    p::DataFrame
    meta::Dict{String, Any}
    DataFrameMeta(args...; kw...) = new(DataFrame(args...; kw...), Dict{Symbol, Any}())
    DataFrameMeta(df::DataFrame) = new(df, Dict{Symbol, Any}())
end
meta(d::DataFrameMeta) = getfield(d,:meta)  # <-- new functionality added to DataFrameMeta
@forward((DataFrameMeta, :p), DataFrame)    # <-- reuse all existing functionalities

while the whole example can be found here.

With the above code we can use an object of type DataFrameMeta as if it was a simple DataFrame, but taking advantage of the new meta method to gain access to the associated metadata dictionary.

Comments are welcome!

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