[bind10-dev] whether/when to use exceptions

[David W. Hankins]

I have one small patch (inline);

On Wed, Oct 14, 2009 at 08:44:09AM -0400, Christos Zoulas wrote:
> This is why in this case it is better to use goto's:
>  
>          fp = fopen("foo.txt", "w");
>          if (fp == NULL)
> 	     goto out;
> 
>          for (i=0; i<10; i++)
>              if (fprintf(fp, "%d\n", i) < 0)
> 		 goto out;
> 
-           if (fclose(fp) != 0)
- 	     got out;
+	    if (fclose(fp) != 0) {
+	      /* Additional calls (e.g. to fclose(fp)) are undefined. */
+	      fp = NULL;
+	      goto out;
+	    }
> 
>          return SUCCESS_CODE;
> out:
> 	 if (fp)
> 	     (void)fclose(fp);
> 	 remove("foo.txt");
> 	 return ERROR_CODE;

Alternatively you can create an 'out2' goto point after the fclose,
this is a little faster as it skips a branch, but it further
complicates what should be a linear code path.

There are some functions in BIND9 (or BIND8 libraries?) which have
nested 3-or-4 deep sections of code and goto's, where each section
had its own new constructions to de-construct, and therefore needed
its own new goto label before the previous label.  I seem to recall
we got those wrong sometimes (cleanup goes in the wrong section).

-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins
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