Support strings (in quotes) as net names

src/circuit.jl

@@ -339,6 +339,10 @@ to a named net. (Such named nets are created as needed.)
     r = resistor(1000), [1] ⟷ src[+], [2] ⟷ gnd
 end
 ```
+
+If a net or pin specification is not just a single symbol or number, and has to
+be put in quotes (e.g. `"in+"`, `"9V"`)
+
 !!! note
     Instead of `⟷` (`\\longleftrightarrow`), one can also use `==`.
 """
@@ -395,6 +399,9 @@ macro circuit(cdef)
         return [QuoteNode(netname)]
     end
 
+    extractpins(netname::String, default_element=nothing) =
+        extractpins(Symbol(netname), default_element)
+
     if !isa(cdef, Expr) || cdef.head !== :block
         error("@circuit must be followed by a begin/end block")
     end

test/runtests.jl

@@ -65,11 +65,11 @@ end
         v_r = i*r
         v_d = 25e-3 * log(i/is+1)
         circ = @circuit begin
-            vsrc = voltagesource(v_r + v_d), [+] ⟷ vcc,[-] ⟷ gnd
+            vsrc = voltagesource(v_r + v_d), [+] ⟷ "supply voltage",[-] ⟷ gnd
             r1 = resistor(r)
             d = diode(is=is), [-] ⟷ gnd, [+] ⟷ r1[2]
             vprobe = voltageprobe(), [-] ⟷ gnd, [+] ⟷ r1[2]
-            r1[1] ⟷ vcc
+            r1[1] ⟷ "supply voltage"
         end
         model = DiscreteModel(circ, 1)
         y = run!(model, zeros(0, 1))