add deprecated file

src/HierarchicalEOM.jl

@@ -138,8 +138,6 @@ module HeomAPI
         addTerminator,
         TimeEvolutionHEOMSol,
         HEOMsolve,
-        evolution,   # has been deprecated, throws error only
-        SteadyState, # has been deprecated, throws error only
         PowerSpectrum,
         DensityOfStates
 
@@ -161,4 +159,6 @@ module HeomAPI
 end
 @reexport using .HeomAPI
 
+include("deprecated.jl")
+
 end

src/deprecated.jl

@@ -0,0 +1,23 @@
+#=
+This file gathers all the deprecated names (structures, functions, or variables) which will be removed in the future major release.
+
+- Before the major release, the deprecated names will just throw errors when they are called.
+- If the deprecated names were once exported, we will still export them here until next major release.
+- If we decide to push a major release, cleanup this file.
+
+Example:
+
+export deprecated_foo
+
+function deprecated_foo(args...; kwargs...)
+    error("`deprecated_foo` has been deprecated and will be removed in next major release, please use `new_foo` instead.")
+end
+=#
+
+export evolution, SteadyState
+
+SteadyState(args...; kwargs...) =
+    error("`SteadyState` has been deprecated, please use `steadystate` instead.")
+
+evolution(args...; kwargs...) =
+    error("`evolution` has been deprecated, please use `HEOMsolve` instead.")

src/evolution.jl

@@ -1,6 +1,3 @@
-evolution(M::AbstractHEOMLSMatrix, args...; kwargs...) =
-    error("`evolution` has been deprecated, please use `HEOMsolve` instead.")
-
 const DEFAULT_ODE_SOLVER_OPTIONS = (abstol = 1e-8, reltol = 1e-6, save_everystep = false, save_end = true)
 
 @doc raw"""

src/steadystate.jl

@@ -1,6 +1,3 @@
-SteadyState(M::AbstractHEOMLSMatrix, args...; kwargs...) =
-    error("`SteadyState` has been deprecated, please use `steadystate` instead.")
-
 @doc raw"""
     steadystate(M::AbstractHEOMLSMatrix; solver, verbose, SOLVEROptions...)
 Solve the steady state of the auxiliary density operators based on `LinearSolve.jl` (i.e., solving ``x`` where ``A \times x = b``).