Dynamic REPL prompt?

Tooling
,
1

How can I make the Julia REPL display a dynamic prompt? For example, how might the REPL print the current date and time in the prompt each time it prints a new prompt?

1 Like
2

Try OhMyREPL. Looks like the dynamic prompt is a recent addition.

4 Likes
3

I just started using OhMyREPL.jl today, but the published documentation still shows the old method signature of input_prompt!:

OhMyREPL.input_prompt!(str::String, color::Symbol)

Given the new input_prompt! signature, how can I determine the signature of the method that input_prompt! will invoke that corresponds to its function argument?

4

You may need to be on the master version of OhMyREPL to get that feature. You can look at methods(OhMyREPL.input_prompt!).

5

I recall encountering the Union{String, Function} argument in input_prompt! in the version of the package that I installed, so I think I have the latest release. It’s the published documentation that is out of date.

Short of looking at the source code of input_prompt!, how can I determine the signature of the method that input_prompt! expects as its first argument?

6

To display the current date in my Julia REPL prompt, I added the following to C:\Users\derek\.julia\config\startup.jl:

using OhMyREPL
using Dates

input_prompt() = "julia-" * string(Dates.now()) * ">"

atreplinit() do repl
  OhMyREPL.input_prompt!(input_prompt)
end

PS C:\Users\derek> julia
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.5.0 (2020-08-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia-2020-08-26T11:20:08.105>

Unfortunately, this prevents the Julia REPL from starting if package OhMyREPL.jl is not installed.

How can I use the startup example in the OhMyREPL.jl documentation with my solution to allow the Julia REPL to start when package OhMyREPL isn’t installed?

7

Does this work?

using Dates
input_prompt() = "julia-" * string(Dates.now()) * ">"

atreplinit() do repl
    try
        @eval using OhMyREPL
        OhMyREPL.input_prompt!(input_prompt)
    catch e
        @warn "error while importing OhMyREPL" e
    end
end
8

No, because @eval using OhMyREPL doesn’t apparently load the module in the same context in which OhMyREPL.input_prompt!(input_prompt) runs:

PS C:\Users\derek> julia
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.5.0 (2020-08-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

┌ Warning: Error while importing OhMyREPL
│   e =
│    MethodError: no method matching input_prompt!(::typeof(input_prompt))
│    The applicable method may be too new: running in world age 27830, while current world is 27837.
│    Closest candidates are:
│      input_prompt!(::Union{Function, String}) at C:\Users\derek\.julia\packages\OhMyREPL\j3mzy\src\prompt.jl:10 (method too new to be called from this world context.)
│      input_prompt!(::Union{Function, String}, ::Any) at C:\Users\derek\.julia\packages\OhMyREPL\j3mzy\src\prompt.jl:10 (method too new to be called from this world context.)
└ @ Main C:\Users\derek\.julia\config\startup.jl:21
julia>
9

This should work then:

using Dates
input_prompt() = "julia-" * string(Dates.now()) * ">"
try 
    using OhMyREPL
catch e
    @warn e
end

atreplinit() do repl
  isdefined(@__MODULE__(), :OhMyREPL) ? OhMyREPL.input_prompt!(input_prompt) : nothing
end

e.g. just separating the try into it’s own block.

10

Yes, that works. :slightly_smiling_face:

With package OhMyREPL.jl installed:

PS C:\Users\derek> julia
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.5.0 (2020-08-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia-2020-08-26T17:04:49.413>

Without package OhMyREPL.jl installed:

PS C:\Users\derek> julia -e 'using Pkg; Pkg.rm(\"OhMyREPL\");'
Updating `C:\Users\derek\.julia\environments\v1.5\Project.toml`
  [5fb14364] - OhMyREPL v0.5.6
Updating `C:\Users\derek\.julia\environments\v1.5\Manifest.toml`
  [a8cc5b0e] - Crayons v4.0.3
  [5fb14364] - OhMyREPL v0.5.6
  [0796e94c] - Tokenize v0.5.8
PS C:\Users\derek> julia
┌ Warning: ArgumentError("Package OhMyREPL not found in current path:\n- Run `import Pkg; Pkg.add(\"OhMyREPL\")` to install the OhMyREPL package.\n")
└ @ Main C:\Users\derek\.julia\config\startup.jl:19
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.5.0 (2020-08-01)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia>
11

I’m still curious what the author had in mind with @eval using OhMyREPL inside the try-catch block.