Re: Newbie Dynamic Data Typing Help

[Hans Aberg]

On 10 Oct 2005, at 20:21, Gill,Michael J wrote:

> Hans,
> Thanks for the response.  So, I can indicate an error in the actions
> with YYERROR if the data type of the VAR from the dtype field of the
> symrec union is wrong.  How do you indicate to Bison that this is an
> error?  Do I need to set YYERROR to something (i.e. True)?

Look in the output file. It is just a macro jumping to the error  
recovery place. There is alos YYABORT, which terminates the parser  
instead. Look in the Bison manual for details.

> Also, I
> don't think I really understand the Bison type system is it  
> possible to
> have a dynamically typed VAR specified in the grammar only without
> checking its type in the actions?

No, only statically typed in Bison static type system. Static =  
compile-time, dynamic = run-time. The grammar actions are executed at  
parser run-time. If VAR is dynamically typed, it must be checked at  
run-time.

  Hans Aberg