Hi! I want to pass an Expr to a function, so it will be able to interact with local variables inside the function. What is the correct way to construct such an expression? Here’s the basic structure of my function that accepts the expression “hook”: function ex_v(v_init::Integer, hook::Expr) …

I think I’ve finally got it, thanks to everyone in this thread for the help!!! :smiley: Here’s the code after it evolved (hehe) through this thread: mutable struct state x::Int64 end generate_candidate_func(hook) = eval( quote state -> begin for t in 1:1000 …

According to an answer in another thread eval always happens at global scope So the question remains: how to pass an Expr to work on local scope? [image] Metaprogramming & variable scope New to Julia I have some function as such: function somefunction(df::AbstractDat…

Some other similar questions: Declaring top level variables in Julia using metaprogramming - Stack Overflow julia - Evaluate expression with local variables - Stack Overflow Julia local variable not defined in expression eval - Stack Overflow Julia global variable in quote expression throws UndefV…

Trying to build upon the solution suggested in Declaring top level variables in Julia using metaprogramming - Stack Overflow , but not getting expected result, the Expr inside the function inside the macro doesn’t seem to be executed. What am I doing wrong? @eval function f(t, hook) x = 0 fo…

[image] FireCrumb: Hi! I want to pass an Expr to a function, so it will be able to interact with local variables inside the function. What is the correct way to construct such an expression? Even if you got this to work, the performance would be terrible, the maintainability would be worse (…

[image] stevengj: What is your ultimate goal here? What kind of functionality do you want to achieve? My ultimate goal is quite complex and well beyond the scope of a single question :sweat_smile: I’m searching, using Evolutionary Algorithm, for different implementations for a function to ac…

[image] FireCrumb: My search candidates are pieces of code represented as Expr objects, which work on a predefined set of variables of known types and names. So the “external caller” can be assumed to be fully aware of the “internal” implementation, that’s not a problem. In other words, your E…

For example: julia> function ex_v(v_init::Integer, hook::Expr) f = eval(:(v -> ($hook; v))) return Base.invokelatest(f, v_init) end ex_v (generic function with 1 method) julia> ex_v(0, :(v = v+1)) 1 Again, however, this is a pretty slow way to evaluate an expression u…

Thanks for all the helpful comments! Important note about Genetic Algorithms (GA): While defining new function (GA ‘solution’) should be fast, it will be executed many times, so execution/evaluation is far more important. [image] stevengj: More generally, the Expr data structure is not really…

Pass expression to manipulate local variable

New to Julia

GunnarFarneback April 18, 2022, 8:45pm 4

You basically can’t do that but depending on what you need to accomplish, the suggestions here might be useful: Passing a string into function as a expression - #14 by GunnarFarneback.

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Evaluation in calling scope? General Usage	22	4463	December 1, 2020
Passing a string into function as a expression General Usage question	17	5813	May 12, 2020
How do I create a function from an expression General Usage question	23	4698	July 13, 2018
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Parsing expressions into functions Performance	22	2065	June 11, 2019

Pass expression to manipulate local variable

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