问题
Assume I have a large connector involving all kinds of base types (Real, Integer, String, Boolean). How can I switch connections based on state events? I would like to do something like this:
model switch
input ComplicatedConnector icon[2];
output ComplicatedConnector ocon;
input Real x;
equation
if x >= 0 then
connect(ocon, icon[1]);
else
connect(ocon, icon[2]);
end if;
end switch;
This does not work. How can it be properly expressed in Modelica?
Answer based on comment by Adrian Pop.
model switch
input ComplicatedConnector icon[2];
output ComplicatedConnector ocon;
input Real x;
ComplicatedConnector con;
initial equation
con = icon[1];
equation
connect(ocon, con);
when x >= 0 then
con := icon[1];
end when;
when x < 0 then
con := icon[2];
end when;
end switch;
Update: The model above is wrong because ocon outputs the initial value of icon[1] forever if no event occurs which is not what you would expect from a switch. Note that this is not due to a wrong answer but due to my false interpretation of the answer. The following model is based on the answer by Michael Tiller.
model switch
input ComplicatedConnector icon[2];
output ComplicatedConnector ocon;
input Real x;
Integer k;
initial equation
k = 1;
equation
ocon = icon[k];
when x >= 0 then
k := 1;
elsewhen x < 0 then
k := 2;
end when;
end switch;
回答1:
Is not possible. You can only switch them based on a parameter known at compile time (also known as structural parameter). The condition in the if equation containing connects needs to be a parameter expression.
回答2:
Note that connect statements are equations. You can expand them out yourself. They exist mainly to avoid "bookkeeping" errors for generating boilerplate equations. So what I suggest you do is simply take your switch model and expand each connect into equations. The it should work.
来源：https://stackoverflow.com/questions/29189519/dynamically-switching-connect-in-modelica