s::String|>Meta.parse|>eval seems good in REPL,but not works when calling julia from C++. I have no idea why? but the following works in both: getproperty(Main,s::String|>Symbol) return DataType define.jl: #!/usr/bin/env julia function define(a::String) exp="mutable struct $a\n\t a::Int\nen…

It seems that eval does not work, when calling from C++ using jl_call. Anyone knows why?

[image] alligatorme: It seems that eval does not work “It does not work” questions rarely garner a useful response. What, specifically, did you try, what was the expected output, and what output did you get?

:sweat_smile:Thank you! the following is my code: function define(a::String) isdefined(Main,a|>Symbol) && return a exp="mutable struct $a\n" for (k,v) in tfull[a] line=isdigit.([k...])|>all ? "$v::NTuple{$k,Cchar}" : "$v::$(get(typet,k) do; define(k); end)" exp*="\t"*line*"\n" end exp*"end…

[image] alligatorme: I cannot get the output of “println(a)" So is the problem with println? That is, if you just replace the whole function with println(a), do you still not get output when you call it with jl_call? (When you say “I cannot get the output”, do you mean that it runs but pro…

After remove the rest code, the println(a) get right output, so I think it is the problem of eval.

I’m afraid that without being more clear about what you’re doing—what C++ code are you running?—and what happens—what is the exact output?—you are not going to get much more help. Also, metaprogramming with strings like this is very much not recommended. It’s the only option in many dynamic languag…

The code in C++ side jl_function_t *obj=jl_get_function(jl_main_module, "define"); jl_value_t *a=jl_cstr_to_string("CThost"); JL_GC_PUSH1(&a); jl_call1(obj,a); JL_GC_POP(); May I have more your advice about the my previous Julia codes about metaprogramming? Thanks

I can’t run any of your example code because it is incomplete. This is what I get when I try to run it: julia> define("Foo") ERROR: UndefVarError: tfull not defined Stacktrace: [1] define(::String) at ./REPL[26]:4 [2] top-level scope at REPL[28]:1 In order to give you more specific advice on how…

What Stefan is saying is: [image] Please read: make it easier to help you Meta Discussion Welcome to the Julia Discourse! We are enthusiastic about helping Julia programmers, both beginner and experienced. This public service announcement (PSA) outlines best practices when…

Got it. I modify the top post and past the simplified code and describe the output results.

Problem calling string parse + eval from C++

General Usage

nilshg May 15, 2019, 3:36pm 10

What Stefan is saying is:

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Problem calling string parse + eval from C++

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