Refactor independent time step argument reads

The code that read the component dts used eval
and symbols to create the component dt vars.

This is changed to keep them in a dict. dt_atmos is
held in this dict, but it is not actually used. I kept
it there for consistency, but it could be removed.

experiments/ClimaEarth/run_amip.jl

@@ -164,28 +164,29 @@ t_end = Float64(time_to_seconds(config_dict["t_end"]))
 t_start = 0.0
 tspan = (t_start, t_end)
 Δt_cpl = Float64(config_dict["dt_cpl"])
-component_dt_names = [:dt_atmos, :dt_land, :dt_ocean, :dt_seaice]
+component_dt_names = ["dt_atmos", "dt_land", "dt_ocean", "dt_seaice"]
+component_dt_dict = Dict{String, Float64}()
 # check if all component dt's are specified
-if all(key -> !isnothing(config_dict[String(key)]), component_dt_names)
+if all(key -> !isnothing(config_dict[key]), component_dt_names)
     # when all component dt's are specified, ignore the dt field
     if haskey(config_dict, "dt")
         @warn "Removing dt in favor of individual component dt's"
         delete!(config_dict, "dt")
     end
     for key in component_dt_names
-        component_dt = Float64(time_to_seconds(config_dict[String(key)]))
+        component_dt = Float64(time_to_seconds(config_dict[key]))
         @assert Δt_cpl % component_dt == 0.0 "Coupler dt must be divisible by all component dt's\n dt_cpl = $Δt_cpl\n $key = $component_dt"
-        eval(:($key = $component_dt))
+        component_dt_dict[key] = component_dt
     end
 else
     # when not all component dt's are specified, use the dt field
     @assert haskey(config_dict, "dt") "dt or (dt_atmos, dt_land, dt_ocean, and dt_seaice) must be specified"
     for key in component_dt_names
-        if !isnothing(config_dict[String(key)])
+        if !isnothing(config_dict[key])
             @warn "Removing $key from config in favor of dt because not all component dt's are specified"
         end
-        delete!(config_dict, String(key))
-        eval(:($key = Float64(time_to_seconds(config_dict["dt"]))))
+        delete!(config_dict, key)
+        component_dt_dict[key] = Float64(time_to_seconds(config_dict["dt"]))
     end
 end
 ## get component model dictionaries (if applicable)
@@ -334,7 +335,7 @@ if mode_name == "amip"
         config_dict["land_albedo_type"],
         config_dict["land_temperature_anomaly"],
         dir_paths;
-        dt = dt_land,
+        dt = component_dt_dict["dt_land"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = land_area_fraction,
@@ -388,7 +389,7 @@ if mode_name == "amip"
     ice_sim = ice_init(
         FT;
         tspan = tspan,
-        dt = dt_seaice,
+        dt = component_dt_dict["dt_seaice"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = ice_fraction,
@@ -432,7 +433,7 @@ elseif mode_name in ("slabplanet", "slabplanet_aqua", "slabplanet_terra")
         config_dict["land_albedo_type"],
         config_dict["land_temperature_anomaly"],
         dir_paths;
-        dt = dt_land,
+        dt = component_dt_dict["dt_land"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = land_area_fraction,
@@ -447,7 +448,7 @@ elseif mode_name in ("slabplanet", "slabplanet_aqua", "slabplanet_terra")
     ocean_sim = ocean_init(
         FT;
         tspan = tspan,
-        dt = dt_ocean,
+        dt = component_dt_dict["dt_ocean"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = (FT(1) .- land_area_fraction), ## NB: this ocean fraction includes areas covered by sea ice (unlike the one contained in the cs)
@@ -482,7 +483,7 @@ elseif mode_name == "slabplanet_eisenman"
         config_dict["land_albedo_type"],
         config_dict["land_temperature_anomaly"],
         dir_paths;
-        dt = dt_land,
+        dt = component_dt_dict["dt_land"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = land_area_fraction,
@@ -497,7 +498,7 @@ elseif mode_name == "slabplanet_eisenman"
     ocean_sim = ocean_init(
         FT;
         tspan = tspan,
-        dt = dt_ocean,
+        dt = component_dt_dict["dt_ocean"],
         space = boundary_space,
         saveat = saveat,
         area_fraction = zeros(boundary_space), # zero, since ML is calculated below
@@ -510,7 +511,7 @@ elseif mode_name == "slabplanet_eisenman"
         tspan,
         space = boundary_space,
         area_fraction = (FT(1) .- land_area_fraction),
-        dt = dt_seaice,
+        dt = component_dt_dict["dt_seaice"],
         saveat = saveat,
         thermo_params = thermo_params,
     )