Make Pluto optional

[Dsantra92]

Introduce Requires and move Pluto dependency to optional. Close #130

[johnnychen94]

Since DemoCards mainly runs on CI(where latency isn't a big deal), Requires is an okay solution already.
But if you'd like to take a try, https://pkgdocs.julialang.org/dev/creating-packages/#Conditional-loading-of-code-in-packages-(Extensions) is a good "official" solution. An extra benefit using Extensions is that we can manage Pluto*'s compatibility.

[Dsantra92]

Faced an interesting problem while following the official example

if !isdefined(Base, :get_extension)
using Requires
# print("Require import block reached")
# end

# if !isdefined(Base, :get_extension)
# print("Require __init__ block reached")
function __init__()
    @require Pluto="c3e4b0f8-55cb-11ea-2926-15256bba5781" begin
      @require PlutoStaticHTML = "359b1769-a58e-495b-9770-312e911026ad" include("../ext/PlutoNotebook.jl")
    end
end
end

Results in an error
ERROR: LoadError: UndefVarError: `@require` not defined

StackTrace

Stacktrace:
 [1] top-level scope
   @ :0
 [2] include
   @ ./Base.jl:456 [inlined]
 [3] include_package_for_output(pkg::Base.PkgId, input::String, depot_path::Vector{String}, dl_load_path::Vector{String}, load_path::Vector{String}, concrete_deps::Vector{Pair{Base.PkgId, UInt128}}, source::Nothing)
   @ Base ./loading.jl:1952
 [4] top-level scope
   @ stdin:2
in expression starting at /home/dsantra/DemoCards.jl/src/DemoCards.jl:60
in expression starting at /home/dsantra/DemoCards.jl/src/DemoCards.jl:1
in expression starting at stdin:2
ERROR: Failed to precompile DemoCards [311a05b2-6137-4a5a-b473-18580a3d38b5] to "/home/dsantra/.julia/compiled/v1.9/DemoCards/jl_j7FQ0Y".
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] compilecache(pkg::Base.PkgId, path::String, internal_stderr::IO, internal_stdout::IO, keep_loaded_modules::Bool)
   @ Base ./loading.jl:2195
 [3] compilecache
   @ ./loading.jl:2068 [inlined]
 [4] _require(pkg::Base.PkgId, env::String)
   @ Base ./loading.jl:1712
 [5] _require_prelocked(uuidkey::Base.PkgId, env::String)
   @ Base ./loading.jl:1567
 [6] macro expansion
   @ ./loading.jl:1555 [inlined]
 [7] macro expansion
   @ ./lock.jl:267 [inlined]
 [8] require(into::Module, mod::Symbol)
   @ Base ./loading.jl:1518

Surprisingly works with comments removed, i.e. requires loaded as a separate if else blocks.

if !isdefined(Base, :get_extension)
using Requires
print("Require import block reached")
end

if !isdefined(Base, :get_extension)
print("Require __init__ block reached")
function __init__()
    @require Pluto="c3e4b0f8-55cb-11ea-2926-15256bba5781" begin
      @require PlutoStaticHTML = "359b1769-a58e-495b-9770-312e911026ad" include("../ext/PlutoNotebook.jl")
    end
end
end

julia> using DemoCards
[ Info: Precompiling DemoCards [311a05b2-6137-4a5a-b473-18580a3d38b5]
Democards dir
Require import block reached
Require __init__ block reached

Any idea why this is happening? Similar problems are happening for julia 1.9 beta3.

[johnnychen94]

I'm not sure. It's perhaps because macros are expanded first?

[Dsantra92]

I decided to leave PlutoDemoCard in the src folder. It might not make sense, now that we are loading Pluto Notebook as an extension. But I didn't want to change the original democard function:

DemoCards.jl/src/types/card.jl

Lines 20 to 34 in d89e89d

	function democard(path::String)::AbstractDemoCard
	validate_file(path)
	_, ext = splitext(path)
	if ext in markdown_exts
	return MarkdownDemoCard(path)
	elseif ext in julia_exts
	if is_pluto_notebook(path)
	return PlutoDemoCard(path)
	else
	return JuliaDemoCard(path)
	end
	else
	return UnmatchedCard(path)
	end
	end

[johnnychen94]

Once the incremental compilation issue is fixed I think it's good to go!

[t-bltg]

Awesome, thanks !