update

Author: TorkelE

docs/src/catalyst_functionality/chemistry_related_functionality.md

@@ -37,6 +37,16 @@ Finally, it is possible to check whether a species is a compound or not using th
 iscompound(CO2)
 ```
 
+!!! note
+    Currently, compounds with components that depend on variables that are not `t` are not supported. E.g. 
+    ```julia
+    @variables x y
+    @species O(x, y) 
+    @compound O2 ~ 2O
+    ```
+    will currently throw an error.
+
+
 Compound components that are also compounds are allowed, e.g. we can create a carbonic acid compound (H₂CO₃) that consists of CO₂ and H₂O:
 ```@example chem1
 @species H(t)

src/chemistry_functionality.jl

@@ -82,8 +82,14 @@ function make_compound(expr)
     components_designation_expr = Expr(:escape, :($species_name = ModelingToolkit.setmetadata($species_name, Catalyst.CompoundComponents, $components)))
     coefficients_designation_expr = Expr(:escape, :($species_name = ModelingToolkit.setmetadata($species_name, Catalyst.CompoundCoefficients, $coefficients))) 
 
+    # Currently, non-t independent variables are not supported for compounds. If there are any like these, we throw an error:
+    non_t_iv_error_check_expr = Expr(:escape, :(issetequal(unique(reduce(vcat, arguments.(ModelingToolkit.unwrap.($components)))), [t]) || error("Currently, compounds depending on components that are not \"t\" are not supported.")))
+
+println(non_t_iv_error_check_expr)
+
     # Returns the rephrased expression.
     return quote
+        $non_t_iv_error_check_expr
         $species_declaration_expr
         $multiple_ivs_error_check_expr
         $iv_designation_expr