Specifying applications in Julia.

This package is a prototype to explore possible ways to define "Application" projects in Julia, see Pkg.jl issue #1962.

The basic idea is that a Julia project can define an "apps" section in its Project.toml, which will speciy the various application entrypoints.

The simplest possible application is a directory containting script which is designed to be called from the command line (e.g. hello_world.jl), along with a Project.toml file specifying this as the entrypoint:

[apps.hello_script]
type = "script"
script = "hello_world.jl"

Calling PkgApp.build() will create an executable file wrapper bin/hello_script which will call this script with the appropriate environment set.

A more complicated application would consist of a regular Julia package containing a "main" function which takes an ARGS argument and returns a Cint, e.g.

module MyApp

function hello_function(ARGS)::Cint
    ...
end

end

The Project.toml would contain the module definition and entrypoint description

name = "MyApp"

[apps.hello_function]
type = "function"
function = "MyApp.hello_world"

Calling PkgApp.build() will create an executable bin/hello_function.