Small enhancements (#10)

* better error messages for dupliacte processes

* add equation function

* version

* even better error message

CHANGELOG.md

@@ -3,6 +3,11 @@
 ProcessBasedModelling.jl follows semver 2.0.
 Changelog is kept with respect to v1 release.
 
+## 1.3
+
+- Better error messages for duplicate processes given to `process_to_mtkmodel`.
+- New exported function `equation(p::Process)` that returns `lhs(p) ~ rhs(p)`.
+
 ## 1.2
 
 The API for default processes has been drastically improved.

Project.toml

@@ -1,7 +1,7 @@
 name = "ProcessBasedModelling"
 uuid = "ca969041-2cf3-4b10-bc21-86f4417093eb"
 authors = ["Datseris <datseris.george@gmail.com>"]
-version = "1.2.4"
+version = "1.3.0"
 
 [deps]
 ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"

src/API.jl

@@ -110,3 +110,10 @@ function lhs_variable(x) # basically x is SymbolicUtils.BasicSymbolic{Real}
     throw(ArgumentError("We analyzed the LHS `$(x)` "*
     "but could not extract a single variable it represents."))
 end
+
+"""
+    equation(process)
+
+Return the `Equation` represented by the given process.
+"""
+equation(proc) = lhs(proc) ~ rhs(proc)

src/ProcessBasedModelling.jl

@@ -23,7 +23,6 @@ export processes_to_mtkmodel
 export new_derived_named_parameter
 export has_symbolic_var, default_value
 export @convert_to_parameters, LiteralParameter
-# export lhs_variable, rhs, lhs # I am not sure whether these should be exported.
-export all_equations
+export all_equations, equation
 
 end

src/make.jl

@@ -67,7 +67,7 @@ function processes_to_mtkmodel(_processes::Vector, default::Dict{Num, Any};
     # Setup: obtain lhs-variables so we can track new variables that are not
     # in this vector. The vector has to be of type `Num`
     lhs_vars = Num[lhs_variable(p) for p in processes]
-    ensure_unique_vars(lhs_vars)
+    ensure_unique_vars(lhs_vars, processes)
     # First pass: generate equations from given processes
     # and collect variables without equations
     incomplete = Num[]
@@ -76,7 +76,7 @@ function processes_to_mtkmodel(_processes::Vector, default::Dict{Num, Any};
     for proc in processes
         append_incomplete_variables!(incomplete, introduced, lhs_vars, proc)
         # add the generated equation in the pool of equations
-        push!(eqs, lhs(proc) ~ rhs(proc))
+        push!(eqs, equation(proc))
     end
     # Second pass: attempt to add default processes to incomplete variables
     # throw an error if default does not exist
@@ -169,9 +169,22 @@ function append_incomplete_variables!(incomplete, introduced, lhs_vars, process)
     return
 end
 
-function ensure_unique_vars(lhs_vars)
+function ensure_unique_vars(lhs_vars, processes)
     nonun = nonunique(lhs_vars)
-    isempty(nonun) || error("The following variables have more than one processes assigned to them: $(nonun)")
+    isempty(nonun) && return # all good!
+    dupprocs = []
+    for var in nonun
+        idxs = findall(p -> Symbol(lhs_variable(p)) == Symbol(var), processes)
+        append!(dupprocs, processes[idxs])
+    end
+    errormsg = """
+    The following variables have more than one processes assigned to them: $(nonun).
+    The duplicate processes are:
+    """
+    for p in dupprocs
+        errormsg *= "\n"*sprint(show, p)
+    end
+    throw(ArgumentError(errormsg))
     return
 end
 

test/runtests.jl

@@ -160,6 +160,11 @@ end
         @test p == 0.5
     end
 
+    @testset "equation" begin
+        @variables x(t)
+        @test equation(ParameterProcess(x, LiteralParameter(0.5))) == (x ~ 0.5)
+    end
+
 end
 
 @testset "default processes, has_thing" begin