Re: Electric cell parameters in Java version

[Steven Rubin]

At 08:45 PM 12/2/2004, you wrote:
> Hi,
>
> I've been trying to include Java code as the value for an attribute. I 
> intend to use other parameter values as variables. The Java documentation, 
> in Section 6-8-6, says that it can be done, but without an example, I'm 
> quite lost. The C documentation, in Section 11-4, gives several code 
> fragments, but they are not accepted when I try them.
>
> Specifically, there is no Electric class, so how would I name the 
> parameters I want to use in the expression?

Parameters have always been confusing in Electric, and although we tried to 
change them to be a bit simpler in the Java version, they are still difficult.

The first thing you need to do is to "declare" the parameter in the 
lower-level cell.  This is done with the "Edit / Properties / Attribute 
Properties" command.  At the top of the dialog, make sure "On Current Cell" 
is selected.  Now you are editing the attributes for the current 
cell.  Type a name and a default value, then click "Create New".  This 
creates the parameter on the cell.  Each instance of the cell that you 
create will have that parameter.  I noticed that there is a bug in 8.00 
which doesn't display the actual parameters on instances of the cell.  But 
if you look at instances with the "Edit / Properties / Object Properties" 
command (^I) and choose the "Attributes" list at the bottom, you will see 
the parameter.

Each instance of the parameterized cell can have a different value for the 
parameter.  That value can be a java expression, a number, or a string.  If 
you use a Java expression, be sure to change the "Code" field to "Java".

Inside of the cell, you can retrieve the value of the parameter by using 
its name with an "@" in front of it inside of a Java expression.  So, for 
example, if you want to use the parameter and place twice its value on an 
arc, double-click the arc to get its Properties dialog, click the 
"Attributes" button, and create a new attribute with the value "@test" 
(assuming that you called the cell parameter "test"), set Code: to Java, 
set Show: to name=value), and click "Create New".  You will now see the 
parameter value.  Try going up and down the hierarchy, into different 
instances of the cell with different parameter values on the instances.

   -Steven Rubin

P.S. A newer Java version of Electric is due out, hopefully this month.