move SemSpec methods from types.jl

Author: Alexey Stukalov

src/frontend/specification/documentation.jl

@@ -1,3 +1,18 @@
+params(spec::SemSpecification) = spec.params
+nparams(spec::SemSpecification) = length(params(spec))
+
+# observed + latent
+vars(spec::SemSpecification) =
+    error("vars(spec::$(typeof(spec))) is not implemented")
+observed_vars(spec::SemSpecification) =
+    error("observed_vars(spec::$(typeof(spec))) is not implemented")
+latent_vars(spec::SemSpecification) =
+    error("latent_vars(spec::$(typeof(spec))) is not implemented")
+
+nvars(spec::SemSpecification) = length(vars(spec))
+nobserved_vars(spec::SemSpecification) = length(observed_vars(spec))
+nlatent_vars(spec::SemSpecification) = length(latent_vars(spec))
+
 """
 `ParameterTable`s contain the specification of a structural equation model.
 

src/types.jl

@@ -342,18 +342,4 @@ Base type for all SEM specifications.
 """
 abstract type SemSpecification end
 
-params(spec::SemSpecification) = spec.params
-nparams(spec::SemSpecification) = length(params(spec))
-
-# observed + latent
-vars(spec::SemSpecification) = error("vars(spec::$(typeof(spec))) is not implemented")
-observed_vars(spec::SemSpecification) =
-    error("observed_vars(spec::$(typeof(spec))) is not implemented")
-latent_vars(spec::SemSpecification) =
-    error("latent_vars(spec::$(typeof(spec))) is not implemented")
-
-nvars(spec::SemSpecification) = length(vars(spec))
-nobserved_vars(spec::SemSpecification) = length(observed_vars(spec))
-nlatent_vars(spec::SemSpecification) = length(latent_vars(spec))
-
 abstract type AbstractParameterTable <: SemSpecification end