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From: ka@cs.washington.edu (Kenneth Almquist)
Newsgroups: comp.lang.ada
Subject: Stylistic question: returning strings vs. pointers to strings
Message-ID: <10968@june.cs.washington.edu>
Date: 5 Mar 90 23:19:17 GMT
Organization: U of Washington, Computer Science, Seattle
List-Id: <comp.lang.ada>

Here's a question about programming style for you to debate.  I have a
package which accesses command line arguments.  My current implementa-
tion is for systems without the concept of a command line arguments;
it reads the command arguments from the standard input.  The interface
to the package consists of two functions:

	nargs - returns the number of command line arguments.
	arg(i) - returns the i'th command line argument.

Being a former C programmer, I naturally made arg(i) return a pointer
to a string, using a separate package named mytypes to contain the
definition of a pointer to a string:

	package mytypes is
	    type string_ptr is access string;
	end mytypes;

	with mytypes; use mytypes;
	package args is
	    function nargs return integer;
	    function arg(index: integer) return string_ptr;
	end args;

Since I haven't been exposed to a lot of Ada programming styles, I'd
be curious to hear from people who would specify the interface differ-
ently, for example making arg(i) return a string rather than a pointer
to a string, or making "arg" a procedure with an "out" argument like
"get_line".
				Kenneth Almquist