Allow interpolation into @remote calls

[KronosTheLate]

Based on this thread, it is possible to process a macro to allow interpolating of values. My use case is that I want to define something like

function get_ADC(addr, bit)
    @remote(pyconvert(Float32, DAQC2.getADC($addr, $bit)))
end

to make it feel like a pure julia function. If I do not interpolate, I get an error from addr and bit not being defined remotely, which makes sense. However, I can not interpolate the arguments into the call to @remote, due to a RemoteException:

ERROR: RemoteException:
  ERROR: syntax: "$" expression outside quote
  Stacktrace:
   [1] top-level scope
     @ none:1
   [2] eval
     @ ./boot.jl:360 [inlined]
  
Stacktrace:
 [1] (::RemoteREPL.var"#47#48"{RemoteREPL.Connection, Expr})()
   @ RemoteREPL ~/.julia/packages/RemoteREPL/BFqrB/src/client.jl:391
 [2] ensure_connected!(f::RemoteREPL.var"#47#48"{RemoteREPL.Connection, Expr}, conn::RemoteREPL.Connection; retries::Int64)
   @ RemoteREPL ~/.julia/packages/RemoteREPL/BFqrB/src/client.jl:178
 [3] ensure_connected!
   @ ~/.julia/packages/RemoteREPL/BFqrB/src/client.jl:174 [inlined]
 [4] remote_eval_and_fetch
   @ ~/.julia/packages/RemoteREPL/BFqrB/src/client.jl:380 [inlined]
 [5] get_ADC(addr::Int64, bit::Int64)
   @ Main ~/Uni/Semester/8. Sem/Independent Study Activity/scripts/test.jl:24
 [6] top-level scope
   @ ~/Uni/Semester/8. Sem/Independent Study Activity/scripts/test.jl:26

The fix would perhaps be to do something like benchmark-tools, as seen in the linked post, to allow interpolation?

[KronosTheLate]

It looks like I can wrap this into an @eval call, and correctly interpolate into that, as a workaround. The following definition works:

function get_ADC(addr, bit)
    @eval @remote(pyconvert(Float32, DAQC2.getADC($addr, $bit)))
end

[c42f]

We should definitely do this. I'm surprised I didn't do it already! (If I recall, I did this exact thing in the SQLStrings/SQLREPL packages.)

[KronosTheLate]

We should definitely do this.

Do you know the appropriate way to do this? I am very inexperienced around macros.

[c42f]

I know how to do it, I just don't have that much time :sweat_smile:

We should try something like

1. After parsing the expression, search it recursively for Expr(:$, ex) expressions
2. call eval(ex) for each of these
3. replace the Expr(:$, ex) part of the expression with the result of the eval
4. Serialize the resulting expression and send it down the pipe to the other end

[KronosTheLate]

Sounds good. I am also pressed for time, but I think it is perfectly fine to keep this issue open as a FR. Perhaps adding a temporary paragraph in the docs about the workaround I found, in case this issue remains open for months/years?