How can I capture the current definition of a method in order to be able to invoke it even if it is later redefined ? That is, how to defeat both the standard method redefinition and Revise ? I’ve looked at the doc, googled it, and searched here for this… it seems I’m missing the right keywords.

julia> f() = 3 f (generic function with 1 method) julia> Base.get_world_counter() 0x0000000000007a08 julia> f() = 5 f (generic function with 1 method) julia> Base.invoke_in_world(0x0000000000007a08, f) 3 [image] ylvain: That is, how to defeat both the standard method redefinition and Revise …

what are you trying to protect against? The methods you “captured” is useless if user don’t also do invoke_in_world when they are not calling your public-facing function. And say they are calling your function, what’s stopping a later package from changing your outer-most functions’ methods? [im…

hum… thank for your reply but I still don’t really get it :sweat_smile: Don’t dynamically time-tarvel with invoke, compiler can’t optimize that. I get it… written a few compilers in a previous life use a internal function to do the un-changing part of your function. it is not unchanging, it …

[image] ylvain: I don’t see any other solution if your new foo rely on old foo, just call the old foo → _foo. This is a common pattern, where the foo is high level / flexible, _foo is directly doing the fixed set of heavy lifting.

you understand they could just override your whole module right? Yeah… but for scenario 1) I’m in the sysimage. Otherwise I couldn’t do anything meaningful anyway. I don’t care what the code calling my code will do. I just want strongest guarantee that if my code do run, then it does what it was…

[image] ylvain: equivalently, all calls from my code could be inlined but this is not gonna happen if you use invoke everywhere?.. I’m probably not understanding your complex use-case

if your new foo rely on old foo , just call the old foo → _foo . This is a common pattern, where the foo is high level / flexible, _foo is directly doing the fixed set of heavy lifting. I’m afraid I’m missing something important here… The old foo is in Base (the actual Base of the Julia distribu…

which function do you have in mind in Base and what do you want to do with it that you think you need invoke?

Again, there are two very different cases Say Base.rm or anything like that that could have catastrophic side effects Say Base.repl_cmd (to continue the example given above) # My Code function Base.repl_cmd(cmd, out) if cmd.exec == ["foo-bar"] # special handling else org…

[image] ylvain: How can I define orginal_base_repl_cmd without invoke_in_world ? You cannot. [image] ylvain: Say Base.rm or anything like that that could have catastrophic side effects That in and of itself is not a problem, no? What do you want to protect yourself against by forcing …

thank you… So I’m not mad :smiley: invoke_in_world is indeed what I was looking for… and the only possible way given the fully dynamic nature of the overrides (with back-link and code re-generation). Question: why is it not in the doc ? I understand that users could abuse it… But the use cas defin…

Capture the current definition of a method

New to Julia

jling August 28, 2021, 4:18pm 23

actually I think opaque closure should do this

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Capture the current definition of a method

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