I don't think we would need attribute values like "public_private" or "both", since I think "public" access should imply "private" access, similar to say c++ or Java's use of those terms.
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Poul Nielsen Sent: Sunday, 23 December 2007 10:25 p.m. To: CellML Discussion List Subject: Re: [cellml-discussion] A list of proposed changes to semantics to makein CellML 1.2 Yes, the scheme that I proposed would not allow variables to 'pass through' the public_interface and private_interface of a component. I imagine that this could be inconvenient in some situations. We could enable this by adding a fourth value, 'public_private', to the attribute list. Best wishes Poul On 2007 Dec 22, at 20:21, Jonathan Cooper wrote: On Sat, Dec 22, 2007 at 11:19:52AM +1300, Poul Nielsen wrote: I think that Jonathan is correct - the concept of 'in' and 'out' does not make sense in a declarative description. One way to remedy this would be to remove the 'public_interface' and 'private_interface' attributes from the <variable> element and replace them with an 'interface' attribute which could assume values "public", "private", or "none". This is a pretty fundamental change to the specification but I think that it better reflects the declarative intent of CellML model descriptions. How would that work for a component like B below, which has both a public and private interface for the same variable? Jonathan. On 2007 Dec 22, at 03:20, Jonathan Cooper wrote: On Thu, Dec 20, 2007 at 12:30:32AM +0800, David Nickerson wrote: * The current specification says: "A variable with either a private_interface or public_interface attribute value of "in" must be mapped to no more than one other variable in the model. [ Note that a similar restriction does not apply to variables with interface values of "out". An output variable can be mapped to multiple input variables in various components in the current model. ]" The problem with this is that it doesn't properly account for mappings where a variable is forwarded into an encapsulated block. As an example, consider the following encapsulation hierarchy (higher components encapsulate lower ones)... A | B / \ C D Suppose that component A has, for variable v, public_interface="none", private_interface="out", and B has for variable v, public_interface="in", private_interface="out" (connected to A), and C and D have public_interface="in", private_interface="none", both of which are connected to B. There is no reason why this should not be valid. However, the specification contradicts itself on whether this is allowed. On one hand, because B has private_interface="out", it "can be mapped to multiple input variables in various components in the current model.", but because it has a public interface of in, it "must be mapped to no more than one other variable in the model". This can be fixed by firstly defining the interpretation of connections and interfaces, and then adding constraints based on that which actually describe which connections are allowed to each set of variables. will be interesting to see how such a definition ties in with the idea of input variables becoming output variables based on the way the components are hooked together :) Indeed. The use of "in" and "out" on interfaces very strongly implies that connections have a directionality, and this is also reflected in the quote from the specification above - it assumes that variables are only defined in one place, and hence it doesn't make sense to import a variable (via an "in" interface) from multiple locations. It does however make sense to export a variable to multiple locations, or forward an imported variable to multiple locations (the example Andrew gives). If we don't want connections to have directionality, then I think this requires quite a major change in the specification, even if only to avoid user confusion. For example, I would want to deprecate the use of "in" and "out", and instead allow public_interface="yes" or public_interface="no" (perhaps a synonym for "none") and similarly for private interfaces. The terms used in the language then reflect the nature of the interfaces - if connections are bidirectional, then it doesn't make sense to talk of an "in" interface, since it may function either as input or output depending on the other components in the system. Jonathan. -- Jonathan Cooper MSN: [EMAIL PROTECTED] www: jonc.me.uk/ We are tribbles of Borg. Prepare to be replicated. _______________________________________________ cellml-discussion mailing list [email protected] http://www.cellml.org/mailman/listinfo/cellml-discussion _______________________________________________ cellml-discussion mailing list [email protected] http://www.cellml.org/mailman/listinfo/cellml-discussion -- Jonathan Cooper MSN: [EMAIL PROTECTED] www: jonc.me.uk/ I haven't lost my mind... It's backed up on tape somewhere. _______________________________________________ cellml-discussion mailing list [email protected] http://www.cellml.org/mailman/listinfo/cellml-discussion
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