Right now we use debug mode (#136) with the special error type for addition of composites to primals failing, to give instructions on how to overload things to fix this.
But in julia 1.5 there is special functionality for adding hints for how to resolve errors build in by some magic:
JuliaLang/julia#35094
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struct PrimalAdditionFailedException{P} <: Exception |
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primal::P |
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differential::Composite{P} |
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original::Exception |
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end |
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function Base.showerror(io::IO, err::PrimalAdditionFailedException{P}) where {P} |
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println(io, "Could not construct $P after addition.") |
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println(io, "This probably means no default constructor is defined.") |
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println(io, "Either define a default constructor") |
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printstyled(io, "$P(", join(propertynames(err.differential), ", "), ")", color=:blue) |
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println(io, "\nor overload") |
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printstyled(io, |
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"ChainRulesCore.construct(::Type{$P}, ::$(typeof(err.differential)))"; |
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color=:blue |
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) |
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println(io, "\nor overload") |
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printstyled(io, "Base.:+(::$P, ::$(typeof(err.differential)))"; color=:blue) |
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println(io, "\nOriginal Exception:") |
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printstyled(io, err.original; color=:yellow) |
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println(io) |
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end |
