externals questions

[Alex Rice]

In the Game of Life external, external.c, I have noticed:

1) String constants are copied before returning, e.g.
*retstring = istrdup("atan2: must pass 2 arguments");
Why is this? It seems to work just as well todo
*retstring = "here is the return value";

2) To indicate a successful call to a handler, it is doing
*retstring = (char *)calloc(1, 1);
What is the significance of the 1 byte? It seems returning NULL works 
just as well and it's one less function call to make.

Alex Rice, Software Developer
Architectural Research Consultants, Inc.
alrice at ARCplanning.com
alrice at swcp.com