Issue with using pyimport in Julia 1.1.0

Question

I made a module with an if condition on the number of cores.

module mymodule

import Pkg
import PyCall

using Distributed

if nworkers() > 1
    @everywhere using Pkg
    @everywhere Pkg.activate(".")
    @everywhere Pkg.instantiate()
    @everywhere using PyCall
    @everywhere @pyimport scipy.signal as ss

    function parallel()
          ....
    end

else
    using Pkg
    Pkg.activate(".")
    Pkg.instantiate()
    using PyCall
    @pyimport scipy.signal as ss
    function serial()
    ....
    end
end
end #mymodule

Code throws the following error on execution

ERROR: LoadError: LoadError: UndefVarError: @pyimport not defined
Stacktrace:
 [1] top-level scope
 [2] include at ./boot.jl:326 [inlined]
 [3] include_relative(::Module, ::String) at ./loading.jl:1038
 [4] include(::Module, ::String) at ./sysimg.jl:29
 [5] include(::String) at ./client.jl:403
 [6] top-level scope at none:0
in expression starting at /storage/work/s/mymodule.jl:81
in expression starting at /storage/work/s/mymodule.jl:30

where line 81 is the line in else condition corresponding to @pyimport scipy.signal as ss and line 30 corresponds to if nworkers() > 1.

Before this problem, the code had an issue with the line @everywhere @pyimport scipy.signal as ss but that disappeared by using import PyCall; bizarrely though, it didn't solve the former problem.

Has anyone experienced a similar issue or aware of such issues?

Answer 1

You need to use pyimport function instead. Macro definition (comes from your using) and usage of that macro in the same block does not work due to the parsing/evaluation order.

Simply change the code

@pyimport scipy.signal as ss

to

ss = pyimport("scipy.signal")

You can also divide the blocks into two, first for the definitions and the second for usage. However, I would not do that as @pyimport macro is already deprecated.