ANN: Exfiltrator

Community
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Exfiltrator (https://github.com/antoine-levitt/Exfiltrator.jl) is Infiltrator’s younger sibling. It exfiltrates local variables to the global scope for easier exploration in the REPL. Example from the readme:

using Exfiltrator

julia> function f(x)
           @exfiltrate
       end
f (generic function with 1 method)

julia> f(2)

julia> x
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There’s also a few variants eg to export variables from multiple calls. Exfiltrator is useful either to debug a program or to export results from deep call stacks (eg for plotting). Feedback welcome!

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Could

@testset "foo" begin
    @exfiltrate
    z = 3
end

be made to work?

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That one is pretty much impossible, because the declaration of z is after the exfiltrate call so it’s not defined at that point. I thought about supporting @exfiltrate VAR function f()... and @exfiltrate VAR begin... which would exfiltrate all locals at the end of the call. That would take care of your case.

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Oh, so I can just put it at the end? That works as well.

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Sure: it just takes its information from Base.@locals, which gives all the currently defined variables.

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Thank you! I like R’s browser() and @infiltrate but sometimes feel constricted by the special REPL. I will definitely use this!

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And, remarkably, it’s 37 lines of code.

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Oh yeah, the thing is completely trivial thanks to the Base.@locals macro, I kind of feel bad for publishing such a stupid thing but it’s useful so… Maybe it could get merged in Infiltrator.jl because it’s similar in purpose, but the name would clash a bit.

Credits go to the people in the slack thread on debugging who said their debugging process is basically exporting variables to the global scope, and to @StefanKarpinski for the idea to just export the variables directly (my previous version exported named tuples only)

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This (and Infiltrator) both look pretty useful. Thanks!

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I’ve been using it and it’s exactly what I needed. Much easier to write data-cleaning code in functions and know where things go wrong.

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This is awesome! It might be only 37 lines of code, but a lot of UI design is trivial but hard to conceive. There is also a knowledge barrier, i.e., I do not know how to implement this macro (I did not know about Base.@locals either), so even though I might have thought of this, because I couldn’t know how much time learning to implement it would take me, I would dismiss the thought.

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Is there some trick to using @exfiltrate in package development? I want to be able to put @exfiltrate inside a function in a package, but I don’t necessarily want to add Exfiltrator as a dependency

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I usually just add using Exfiltrator at the beginning of a file and Revise takes care of it. It’d be great to get rid of the using but I don’t know how

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add it to your global enviroment.
then it doesn;t have to be in the project’s dependnecies

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Wait, can packages access global dependencies? I thought they were only visible at the REPL.

I would try using Exfiltrator at the REPL, then in the package code use Main.@exfiltrate

1 Like
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Good trick, thanks!

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Thanks! Actually I had the same question for Infiltrator.jl. This is a very smart trick.

However, the lines with Main.@exfiltrate will still throw an error if you forget to delete them after debugging. I have not yet tested it, but perhaps that could be avoided with:

isdefined(Main, :Exfiltrator) && Main.Exfiltrator.@exfiltrate

(Added Main.Exfiltrator in case the package it is “imported”, instead of “used”.)