Added @prefix macro which calls prefix with a Val argument to

make things easier to basic users

Author: torfjelde

src/contexts.jl

@@ -294,6 +294,34 @@ function prefix(::PrefixContext{Prefix}, vn::VarName{Sym}) where {Prefix,Sym}
     end
 end
 
+"""
+    prefix(model::Model, x)
+
+Return `model` but with all random variables prefixed by `x`.
+
+If `x` is known at compile-time, use `Val{x}()` to avoid runtime overheads for prefixing.
+"""
+prefix(model::Model, x) = contextualize(model, PrefixContext{Symbol(x)}(model.context))
+function prefix(model::Model, ::Val{x}) where {x}
+    contextualize(model, PrefixContext{Symbol(x)}(model.context))
+end
+
+"""
+    @prefix(model, prefix_expr)
+
+Return `model` but with all random variables prefixed by `prefix_expr`.
+
+The result of `prefix_expr` must will be converted to a `Symbol` and used as the prefix.
+
+!!! note
+    This is effectively just a convenience macro for the method [`prefix(::Model, x)`](@ref),
+    which automatically converts the result of `prefix_expr` into a `Val` to avoid runtime overheads
+    for static prefixes. For more control over the prefixing, use the method directly.
+"""
+macro prefix(model, prefix_expr)
+    return :($prefix($(esc(model)), $Val{$(esc(prefix_expr))}()))
+end
+
 struct ConditionContext{Values,Ctx<:AbstractContext} <: AbstractContext
     values::Values
     context::Ctx

src/submodel_macro.jl

@@ -250,16 +250,15 @@ function submodel(prefix_expr, expr, ctx=esc(:__context__))
 end
 
 """
-    @returned_quantities [prefix=...] model
+    @returned_quantities model
 
 Run `model` nested inside of another model and return the return-values of the `model`.
 
-Valid expressions for `prefix=...` are:
-- `prefix=false`: no prefix is used. This is the default.
-- `prefix=expression`: results in the prefix `Symbol(expression)`.
-
-Prefixing makes it possible to run the same model multiple times while keeping track of
-all random variables correctly, i.e. without name clashes.
+!!! warning
+    It's generally recommended to use [`prefix(::Model, x)`](@ref) or
+    [`@prefix(model, prefix_expr)`](@ref) in combination with `@returned_quantities`
+    to ensure that the variables in `model` are unique and do not clash with other variables in the
+    parent model or in other submodels.
 
 # Examples
 
@@ -308,8 +307,8 @@ julia> @model function demo1(x)
        end;
 
 julia> @model function demo2(x, y, z)
-            a = @returned_quantities prefix="sub1" demo1(x)
-            b = @returned_quantities prefix="sub2" demo1(y)
+            a = @returned_quantities prefix(demo1(x), Val{:sub1}())
+            b = @returned_quantities prefix(demo1(y), Val{:sub2}())
             return z ~ Uniform(-a, b)
        end;
 ```