Merge pull request #1569 from SciML/myb/error_check

Use Connection from Symbolics

Author: YingboMa

Project.toml

@@ -73,7 +73,7 @@ Setfield = "0.7, 0.8"
 SpecialFunctions = "0.7, 0.8, 0.9, 0.10, 1.0, 2"
 StaticArrays = "0.10, 0.11, 0.12, 1.0"
 SymbolicUtils = "0.19"
-Symbolics = "4.3"
+Symbolics = "4.5"
 UnPack = "0.1, 1.0"
 Unitful = "1.1"
 julia = "1.6"

src/ModelingToolkit.jl

@@ -45,7 +45,8 @@ using Reexport
 export @derivatives
 using Symbolics: _parse_vars, value, @derivatives, get_variables,
                  exprs_occur_in, solve_for, build_expr, unwrap, wrap,
-                 VariableSource, getname, variable
+                 VariableSource, getname, variable, Connection, connect,
+                 NAMESPACE_SEPARATOR
 import Symbolics: rename, get_variables!, _solve, hessian_sparsity,
                   jacobian_sparsity, isaffine, islinear, _iszero, _isone,
                   tosymbol, lower_varname, diff2term, var_from_nested_derivative,

src/systems/connectors.jl

@@ -56,19 +56,8 @@ function connector_type(sys::AbstractSystem)
     n_stream > 0 ? StreamConnector() : RegularConnector()
 end
 
-struct Connection
-    systems
-end
-Connection() = Connection(nothing)
 get_systems(c::Connection) = c.systems
 
-# symbolic `connect`
-function connect(sys1::AbstractSystem, sys2::AbstractSystem, syss::AbstractSystem...)
-    syss = (sys1, sys2, syss...)
-    length(unique(nameof, syss)) == length(syss) || error("connect takes distinct systems!")
-    Equation(Connection(), Connection(syss)) # the RHS are connected systems
-end
-
 instream(a) = term(instream, unwrap(a), type=symtype(a))
 SymbolicUtils.promote_symtype(::typeof(instream), _) = Real