Allow cascading links, e.g. x - y - z

README.md

@@ -40,10 +40,8 @@ class Example(VA.Module):
         # link created modules together, from left to right
         self('INBOUND') - branch
         branch(0) - decision
-        branch(1) - condition
-        branch(2) - value
-        condition - decision('C')
-        value - decision('E')
+        branch(1) - condition - decision('C')
+        branch(2) - value - decision('E')
         decision - self('OUTBOUND')
 
         # for instance, set desired link properties
@@ -53,8 +51,8 @@ class Example(VA.Module):
         value('O')['Arithmetic'] = 'signed'  # (needs to match the input link)
 
         # for instance, set desired module properties
-        condition['Number'] = 0
-        value['Value'] = 0
+        condition['Number'] = 0  # input value threshold
+        value['Value'] = 0       # output value below threshold
 ```
 
 Now the second part of our Python script:

example.py

@@ -17,10 +17,8 @@ def __init__(self, parent, name, x, y):
         # link created modules together, from left to right
         self('INBOUND') - branch
         branch(0) - decision
-        branch(1) - condition
-        branch(2) - value
-        condition - decision('C')
-        value - decision('E')
+        branch(1) - condition - decision('C')
+        branch(2) - value - decision('E')
         decision - self('OUTBOUND')
 
         # for instance, set desired link properties
@@ -30,8 +28,8 @@ def __init__(self, parent, name, x, y):
         value('O')['Arithmetic'] = 'signed'  # (needs to match the input link)
 
         # for instance, set desired module properties
-        condition['Number'] = 0
-        value['Value'] = 0
+        condition['Number'] = 0  # input value threshold
+        value['Value'] = 0       # output value below threshold
 
 
 if __name__ == '__main__':

example.tcl

@@ -10,8 +10,8 @@ CreateModule "IF" "Process0/Example/Decision" "0" "0" "326" "43"
 ConnectModules "Process0/Example" "INBOUND#I000" "Process0/Example/Branch" "I"
 ConnectModules "Process0/Example/Branch" "O000" "Process0/Example/Decision" "I000"
 ConnectModules "Process0/Example/Branch" "O001" "Process0/Example/Condition" "I"
-ConnectModules "Process0/Example/Branch" "O002" "Process0/Example/Value" "I"
 ConnectModules "Process0/Example/Condition" "O" "Process0/Example/Decision" "Condition000"
+ConnectModules "Process0/Example/Branch" "O002" "Process0/Example/Value" "I"
 ConnectModules "Process0/Example/Value" "O" "Process0/Example/Decision" "ElseI"
 ConnectModules "Process0/Example/Decision" "O" "Process0/Example" "OUTBOUND#O000"
 SetLinkParam "Process0/Example/Branch" "I" "Bit Width" "16"

visualapplets.py

@@ -136,6 +136,8 @@ def __call__(self, *port_args):
 
     def __sub__(self, other):
 
+        assert isinstance(other, (Module, Port))
+
         src = self()
         dst = other() if isinstance(other, Module) else other
 
@@ -180,6 +182,8 @@ def __setitem__(self, param_name, param_value):
 
     def __sub__(self, other):
 
+        assert isinstance(other, (Module, Port))
+
         src = self
         dst = other() if isinstance(other, Module) else other
 
@@ -221,6 +225,15 @@ def __setitem__(self, param_name, param_value):
 
         return Param(self, param_name, param_value)
 
+    def __sub__(self, other):
+
+        assert isinstance(other, (Module, Port))
+
+        src = self.dst.module()
+        dst = other() if isinstance(other, Module) else other
+
+        return src - dst
+
 
 class Param: