Feature request: Make Pkg load automatically in the REPL

[DilumAluthge]

From a Slack conversation with @KristofferC:

We should make Pkg load automatically in the REPL
Same as InteractiveUtils

[fredrikekre]

See #28206

[JeffBezanson]

You can put this in your juliarc if you want.

[StefanKarpinski]

You can, but the problem that one wants to address is the awkwardness of giving people instructions for running Pkg commands. The instructions always have to say:

To fix whatever, run `import Pkg; Pkg.add("Foo")`

The fact that people can add import Pkg to their startup.jl file doesn't solve that because we can't assume that they've done that. If it was available by default then we could write

To fix whatever, run `Pkg.add("Foo")`

[Keno]

Maybe exporting it from InteractiveUtils would be a non-offensive way to get this done? That way people could still add local bindings to main to use a different Pkg, but if it's not there it'll pick up the export.

[StefanKarpinski]

Ah, that's smart. Edit: wait, does that work?

[Keno]

Edit: wait, does that work?

It works as any other binding does:

julia> using Pkg

julia> const Pkg = Base
ERROR: invalid redefinition of constant Pkg
Stacktrace:
 [1] top-level scope at REPL[2]:1

julia> module Foo; using Pkg; export Pkg; end
Main.Foo

julia> using .Foo

julia> const Pkg = Base
Base

julia> module Foo; using Pkg; export Pkg; end
Main.Foo

julia> using .Foo

julia> Pkg.add("WAT?!")
ERROR: WAT?! is not a valid packagename.

Not sure that's the issue you were worried about.

[Keno]

Welp, I just realized that that's what we did before fbc30cd.

[Keno]

Perhaps we can figure out another way to break that cycle, perhaps by splitting up InteractiveUtils into two modules.