Move JLD2 dependency to package extension

Author: simsurace

Project.toml

@@ -1,14 +1,19 @@
 name = "MetaGraphsNext"
 uuid = "fa8bd995-216d-47f1-8a91-f3b68fbeb377"
-version = "0.7.5"
+version = "0.8.0"
 
 [deps]
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
-JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 SimpleTraits = "699a6c99-e7fa-54fc-8d76-47d257e15c1d"
 
+[weakdeps]
+JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
+
+[extensions]
+MetaGraphsNextJLD2Ext = ["Graphs", "JLD2"]
+
 [compat]
 Graphs = "1.4.1"
 JLD2 = "0.1.11, 0.2, 0.3, 0.4, 0.5, 0.6"
 SimpleTraits = "0.9"
-julia = "1.6"
+julia = "1.10"

ext/MetaGraphsNextJLD2Ext.jl

@@ -0,0 +1,18 @@
+module MetaGraphsNextJLD2Ext
+
+using Graphs
+using JLD2
+using MetaGraphsNext
+
+function MetaGraphsNext.loadmg(file::AbstractString)
+    @load file meta_graph
+    return meta_graph
+end
+
+function MetaGraphsNext.savemg(file::AbstractString, meta_graph::MetaGraph)
+    @save file meta_graph
+    return 1
+end
+
+
+end

src/MetaGraphsNext.jl

@@ -5,7 +5,6 @@ A package for graphs with vertex labels and metadata in Julia. Its main export i
 """
 module MetaGraphsNext
 
-using JLD2
 using Graphs
 using SimpleTraits
 
@@ -24,4 +23,19 @@ include("dict_utils.jl")
 include("weights.jl")
 include("persistence.jl")
 
+function __init__()
+    # Register error hint for the `loadmg` and `savemg`
+    if isdefined(Base.Experimental, :register_error_hint)
+        Base.Experimental.register_error_hint(MethodError) do io, exc, _, _
+            if exc.f === loadmg
+                print(io, "\n\nIn order to load meta graphs from binary files, you need \
+                to load the JLD2.jl package.")
+            elseif exc.f === savemg
+                print(io,"\n\nIn order to save meta graphs to binary files, you need to \
+                load the JLD2.jl package.")
+            end
+        end
+    end
+end
+
 end # module

src/persistence.jl

@@ -1,32 +1,23 @@
-# Metagraphs files are simply JLD2 files.
-
 """
     struct MGFormat <: AbstractGraphFormat end
 
 You can save `MetaGraph`s in a `MGFormat`, currently based on `JLD2`.
 """
 struct MGFormat <: Graphs.AbstractGraphFormat end
 
+function loadmg end
+function savemg end
+
+Graphs.loadgraph(file::AbstractString, ::String, ::MGFormat) = loadmg(file)
+Graphs.savegraph(file::AbstractString, meta_graph::MetaGraph) = savemg(file, meta_graph)
+
 """
     struct DOTFormat <: AbstractGraphFormat end
 
 If all metadata types support `pairs` or are `Nothing`, you can save `MetaGraph`s in `DOTFormat`.
 """
 struct DOTFormat <: Graphs.AbstractGraphFormat end
 
-function loadmg(file::AbstractString)
-    @load file meta_graph
-    return meta_graph
-end
-
-function savemg(file::AbstractString, meta_graph::MetaGraph)
-    @save file meta_graph
-    return 1
-end
-
-Graphs.loadgraph(file::AbstractString, ::String, ::MGFormat) = loadmg(file)
-Graphs.savegraph(file::AbstractString, meta_graph::MetaGraph) = savemg(file, meta_graph)
-
 function show_meta_list(io::IO, meta)
     if meta !== nothing && length(meta) > 0
         next = false

test/Project.toml

@@ -4,6 +4,7 @@ BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
+JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 MetaGraphs = "626554b9-1ddb-594c-aa3c-2596fe9399a5"
 SimpleTraits = "699a6c99-e7fa-54fc-8d76-47d257e15c1d"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

test/runtests.jl

@@ -1,6 +1,7 @@
 using Aqua
 using Documenter
 using Graphs
+using JLD2
 using MetaGraphsNext
 using Test