Fix depwarnings of Requires in Julia v0.7

src/Approximations/overapproximate.jl

@@ -146,8 +146,6 @@ function overapproximate(X::LazySet{N},
     return H
 end
 
-@require IntervalArithmetic begin
-
 """
     overapproximate(::LazySet{N}, ::Type{LazySets.Interval}) where {N<:Real}
 
@@ -168,5 +166,3 @@ function overapproximate(S::LazySet{N}, ::Type{LazySets.Interval}) where {N<:Rea
     hi = σ([one(N)], S)[1]
     return LazySets.Interval(lo, hi)
 end
-
-end # @require

src/HPolytope.jl

@@ -201,7 +201,8 @@ function tosimplehrep(P::HPolytope{N}) where {N}
     return (A, b)
 end
 
-@require Polyhedra begin
+function load_polyhedra_hpolytope() # function to be loaded by Requires
+return quote
 
 using CDDLib # default backend
 import Polyhedra:polyhedron, SimpleHRepresentation, SimpleHRepresentation,
@@ -347,5 +348,5 @@ function vertices_list(P::HPolytope{N};
     prunefunc(P)
     return [vi for vi in vreps(P)]
 end
-
-end
+end # quote
+end # function load_polyhedra_hpolytope()

src/LazySets.jl

@@ -85,4 +85,9 @@ include("Approximations/Approximations.jl")
 # ============
 include("plot_recipes.jl")
 
+# ===================================================
+# Load external packages on-demand (using 'Requires')
+# ===================================================
+include("init.jl")
+
 end # module

src/VPolytope.jl

@@ -103,7 +103,8 @@ function vertices_list(P::VPolytope{N})::Vector{Vector{N}} where {N<:Real}
 end
 
 
-@require Polyhedra begin
+function load_polyhedra_vpolytope() # function to be loaded by Requires
+return quote
 
 using CDDLib # default backend
 import Polyhedra:polyhedron, SimpleHRepresentation, SimpleVRepresentation,
@@ -222,4 +223,5 @@ function cartesian_product(P1::VPolytope, P2::VPolytope; backend=CDDLib.CDDLibra
     return VPolytope(Pcp)
 end
 
-end
+end # quote
+end # function load_polyhedra_vpolytope()

src/init.jl

@@ -0,0 +1,8 @@
+function __init__()
+    @require Polyhedra = "67491407-f73d-577b-9b50-8179a7c68029" load_polyhedra()
+end
+
+function load_polyhedra()
+    eval(load_polyhedra_hpolytope())
+    eval(load_polyhedra_vpolytope())
+end