Move JLD2.jl dependency to a package extension

Project.toml

@@ -1,19 +1,25 @@
 name = "StaticGraphs"
 uuid = "4c8beaf5-199b-59a0-a7f2-21d17de635b6"
-version = "0.3.1"
+version = "0.4.0"
 
 [deps]
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
-JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 
+[weakdeps]
+JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
+
+[extensions]
+StaticGraphsJLD2Ext = "JLD2"
+
 [compat]
 Graphs = "1.4"
 JLD2 = "0.1 - 0.6"
-julia = "1"
+julia = "1.10"
 
 [extras]
+JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Test"]
+test = ["JLD2", "Test"]

ext/StaticGraphsJLD2Ext.jl

@@ -0,0 +1,32 @@
+module StaticGraphsJLD2Ext
+
+using JLD2
+using StaticGraphs
+
+function StaticGraphs.savesg(fn::AbstractString, g::StaticGraph)
+    f_ind = g.f_ind
+    f_vec = g.f_vec
+    @save fn f_vec f_ind
+    return 1
+end
+
+function StaticGraphs.savesg(fn::AbstractString, g::StaticDiGraph)
+    f_ind = g.f_ind
+    f_vec = g.f_vec
+    b_ind = g.b_ind
+    b_vec = g.b_vec
+    @save fn f_vec f_ind b_vec b_ind
+    return 1
+end
+
+function StaticGraphs.loadsg(fn::AbstractString, ::SGFormat)
+    @load fn f_vec f_ind
+    return StaticGraph(f_vec, f_ind)
+end
+
+function StaticGraphs.loadsg(fn::AbstractString, ::SDGFormat)
+    @load fn f_vec f_ind b_vec b_ind
+    return StaticDiGraph(f_vec, f_ind, b_vec, b_ind)
+end
+
+end

src/StaticGraphs.jl

@@ -1,7 +1,6 @@
 module StaticGraphs
 
 using Graphs
-using JLD2
 using SparseArrays
 
 import Base:
@@ -115,4 +114,19 @@ eltype(::Type{StaticEdgeIter{StaticDiGraph{T, U}}}) where T where U = StaticDiGr
 
 include("overrides.jl")
 
+function __init__()
+    # Register error hint for the `loadsg` and `savesg` functions
+    if isdefined(Base.Experimental, :register_error_hint)
+        Base.Experimental.register_error_hint(MethodError) do io, exc, _, _
+            if exc.f === loadsg
+                print(io, "\n\nIn order to load static graphs from binary files, you need \
+                to load the JLD2.jl package.")
+            elseif exc.f === savesg
+                print(io,"\n\nIn order to save static graphs to binary files, you need to \
+                load the JLD2.jl package.")
+            end
+        end
+    end
+end
+
 end # module

src/persistence.jl

@@ -7,31 +7,8 @@ abstract type StaticGraphFormat <: AbstractGraphFormat end
 struct SGFormat <: StaticGraphFormat end
 struct SDGFormat <: StaticGraphFormat end
 
-function savesg(fn::AbstractString, g::StaticGraph)
-    f_ind = g.f_ind
-    f_vec = g.f_vec
-    @save fn f_vec f_ind
-    return 1
-end
-
-function savesg(fn::AbstractString, g::StaticDiGraph)
-    f_ind = g.f_ind
-    f_vec = g.f_vec
-    b_ind = g.b_ind
-    b_vec = g.b_vec
-    @save fn f_vec f_ind b_vec b_ind
-    return 1
-end
-
-function loadsg(fn::AbstractString, ::SGFormat)
-    @load fn f_vec f_ind
-    return StaticGraph(f_vec, f_ind)
-end
-
-function loadsg(fn::AbstractString, ::SDGFormat)
-    @load fn f_vec f_ind b_vec b_ind
-    return StaticDiGraph(f_vec, f_ind, b_vec, b_ind)
-end
+function loadsg end
+function savesg end
 
 loadgraph(fn::AbstractString, gname::String, s::StaticGraphFormat) = loadsg(fn, s)
-savegraph(fn::AbstractString, g::AbstractStaticGraph) =  savesg(fn, g)
+savegraph(fn::AbstractString, g::AbstractStaticGraph) = savesg(fn, g)

test/runtests.jl

@@ -1,6 +1,7 @@
 using StaticGraphs
 using Graphs
 using Graphs.SimpleGraphs
+using JLD2
 using Test
 
 const testdir = dirname(@__FILE__)