RE: [sv-bc] BNF too restrictive for macro actual arg

Greg,

Here is Syntax 21-2

text_macro_definition ::=
	`define text_macro_name macro_text
text_macro_name ::=
	text_macro_identifier [ ( list_of_formal_arguments ) ]
list_of_formal_arguments ::=
	formal_argument { , formal_argument }
formal_argument ::=
	simple_identifier [ = default_text ]
text_macro_identifier ::=
	identifier
 

This uses "default_text" as the default argument for the macros, though it doesn't formally define "default_text"  Should we make this and definition of "actual_argument" from Syntax 21-3 the same thing?  

Because both must play by the exact same rules right, whatever is legal/illegal as a macro argument is the same whether its given as the default argument in the macro definition, or as an actual argument in the macro instance.  Or do these need to be treated differently somehow?

But I agree on your point that  actual_argument ::= expression is too restrictive.

~Alex


-----Original Message-----
From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On Behalf Of Greg Jaxon
Sent: Monday, July 07, 2008 7:32 PM
To: SV_BC List
Subject: [sv-bc] BNF too restrictive for macro actual arg

Syntax 21-3 says:

> text_macro_usage ::=
>         `text_macro_identifier [ ( list_of_actual_arguments ) ]
> list_of_actual_arguments ::=
>         actual_argument { , actual_argument }
> actual_argument ::=
>         expression

But surely the actuals are not required to be expressions.

Accompanying text says only that:
> To use a macro defined with arguments, the name of the text macro shall be followed by a list of actual argu-
> ments in parentheses, separated by commas. Actual arguments and defaults shall not contain comma or right
> parenthesis characters outside matched pairs of left and right parentheses (), square brackets [], braces {},
> double quotes "", or an escaped identifier.

and further offers this:
> An actual argument may be empty or white space only, in which case the formal argument is substituted by
> the argument default if one is specified or by nothing if no default is specified.

I think the BNF production should simply say

         actual_argument ::=  {any_character}¹

with the footnote containing or referring to the more subtle restrictions I quoted above.

Greg


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.