Printing from a task

General Usage
, ,
1

In testing my package I have problems to print from an asynchronous task to the REPL. Here is a MWE:

struct Msg
    a
    b
end

function tpr(ch::Channel)
    while true
        msg = take!(ch)
        if msg isa Msg
            println(msg.a, " ", msg.b)  # should print one line + CR
        else
            break
        end
    end
end

ch = Channel(tpr)  # I setup tpr as a task on a channel

If I send a message to my task, I get the following:

julia> put!(ch, Msg("first", "second"))
first secondMsg
("first", "second")

julia> put!(ch, Msg("first", "second"));
first 
julia> 
julia>
  1. case (without ;) I get the CR after the command has returned (not after the task printout).
  2. case (with ;) I am loosing the 2nd message argument entirely.

Am I missing something? How can I print correctly from a task? Any advice?

versioninfo() 
julia> versioninfo()
Julia Version 1.4.2
Commit 44fa15b150* (2020-05-23 18:35 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin18.7.0)
  CPU: Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-8.0.1 (ORCJIT, skylake)
Environment:
  JULIA_NUM_THREADS = 8
  JULIA_EDITOR = atom  -a
2

Now I found one solution: Since obviously my println command with multiple arguments causes as many times a yield(), I have to compose my output string before printing it. With

using Printf

function tpr(ch::Channel)
    ...
        print(@sprintf("%s %s\n", msg.a, msg.b))
    ...
end

I get the right printouts:

julia> put!(ch, Msg("first", "second"))
first second
Msg("first", "second")

julia> put!(ch, Msg("first", "second"));
first second

julia>