Relvar syntax definition
Posted: Sat Aug 18, 2012 2:26 pm
I have been looking at the syntax of Rel, and am having difficulty following the definition for RelVar. It defines var_relvar as:
var_relvar ::= ( <REAL> | <BASE> ) var_type_or_init_value var_keydeflist
| <PRIVATE> var_type_or_init_value var_keydeflist
| <PUBLIC> type_ref var_keydeflist
| <VIRTUAL> expression var_keydeflistoptional
[Ignoring for the purpose of this question, the alternative parts of this definition.]
The (<REAL> | <BASE>) and var_keydeflist make sense to me, but the var_type_or_init_value part seems, if followed through to define a single type definition. What I cannot see is how the attribute list for the relvar is defined. I expected it to be this part of the definition. As it does not appear to be the definition of the attribute list, what is it defining? and where is the attribute part of relvar definition?
I am assuming that it is my lack of understanding that is the problem, as I presume the documentation is derived from the parsing system.
Thanks for any light you can throw on this.
Chris Walton
var_relvar ::= ( <REAL> | <BASE> ) var_type_or_init_value var_keydeflist
| <PRIVATE> var_type_or_init_value var_keydeflist
| <PUBLIC> type_ref var_keydeflist
| <VIRTUAL> expression var_keydeflistoptional
[Ignoring for the purpose of this question, the alternative parts of this definition.]
The (<REAL> | <BASE>) and var_keydeflist make sense to me, but the var_type_or_init_value part seems, if followed through to define a single type definition. What I cannot see is how the attribute list for the relvar is defined. I expected it to be this part of the definition. As it does not appear to be the definition of the attribute list, what is it defining? and where is the attribute part of relvar definition?
I am assuming that it is my lack of understanding that is the problem, as I presume the documentation is derived from the parsing system.
Thanks for any light you can throw on this.
Chris Walton