Hi Andrew and Lars:

I inspected Doug's code and found:

Utils {
  /** Make sure file exists and is readable. */
  public static InputStream makeInputStream(File file)
   throws IOException
  (@
    if (!file.exists()) {
      Stream.err.println("Error: Input file " + file + " does not exist.");
    } else if (!file.canRead()) {
      Stream.err.println("Error: Input file " + file +
			 " exists but is not readable.");
    } else if (!file.isFile()) {
      Stream.err.println("Error: Input file " + file +
			 " is not a plain file.");
    } else try {
      FileInputStream in = new FileInputStream(file);
      return in;
    } catch (FileNotFoundException exc) {
      // This shouldn't happen...
      throw new RuntimeException(exc.toString());
    }
    throw new IOException();
  @)
}

Checking the cd:

MethodDef               = MethodSignature MethodBody.
MethodSignature         = <keywords> List(MethodKeyword)
			  <returnType> JavaType <name> MethodName
			"(" [ <parms> Commalist(MethodParm) ] ")"
			<throwsclause> Throws.

Throws                  = [ *s "throws" <exceptions> Commalist(ClassName) ].
MethodBody              : VerbatimMethodBody | AdaptiveMethodBody
			| NoMethodBody.

This means that adaptive methods can throw exceptions.

You can write something like:

void f() throws IOException to A (Visitor);

Does this help?

-- Karl

From lth@ccs.neu.edu Wed Jun  3 09:01:54 1998
To: amiller@xis.xerox.com (Andrew Miller)
cc: lieber@ccs.neu.edu, com3362@ccs.neu.edu, dem@ccs.neu.edu
Subject: Re: Re[4]: Demjava 
From: Lars Thomas Hansen <lth@ccs.neu.edu>


>     Is there a way to delcare a traversal as "throws <exceptiontype>"?  
>     Without this capability I don't think Java will let me throw the 
>     exception.

This capability was designed (but never implemented) for an earlier
version of Demeter/Java (see
http://www.ccs.neu.edu/home/lth/aao/index.html).  You're right --
without it, you won't be able to use exceptions in a sensible manner.

--lars

From amiller@xis.xerox.com Wed Jun  3 08:48:03 1998

     Is there a way to delcare a traversal as "throws <exceptiontype>"?  
     Without this capability I don't think Java will let me throw the 
     exception.
     
     Andrew


______________________________ Reply Separator _________________________________
Subject: Re:  Re[2]: Demjava
Author:  Karl Lieberherr <lieber@ccs.neu.edu> at intergate
Date:    6/3/98 5:21 AM


Andrew Miller writes:
     Ok.  Now another question.  Have you added some kind of early-out 
     construct to traversals?  Let's say I was searching for something and 
     I've found it.  I now want to end the traversal.  
     
No we don't have a structure-shy construct to get out from a deep traversal. 
It is something we have been thinking about.
     
Your implementation will give some clues on how to approach this.
     
-- Karl