Using Posix with Apex

[pvanbell@cloud9.net (Paul Van Bellinghen)]

 I don't know how many of you are using Rational Apex, but if you are
and want to write any code to extract arguments from a command line,
I had a devel of a time doing it. I recently modified a program that
counted lines of Ada code to take its two arguments (output file,
input file list) from the command line. I was compiling it with
Rational Apex and so I used the Posix
package provided. In order to get say, the first argument on the
command line, I wrote:

Output_File_Name.Name :=
	   Posix.To_String (Posix.Value
           (Posix_Process_Environment.Argument_List, 2));

however, I kept getting an "invalid argument" exception when the code
was executed. I called the  Rational support team and found out that
the line suld read

	Output_File_Name.Name
	   (1 .. Posix.To_String
           (Posix.Value (Posix_Process_Environment.Argument_List, 2))'
		 Length) :=
	   Posix.To_String (Posix.Value
           (Posix_Process_Environment.Argument_List, 2));

The problem was that Output_File_Name.Name and the argument to be
assigned to it had different lengths. This is not allowed by Ada's
rules for assigning to arrays - you must specify which elements of
the array are to be assigned values when the right-hand-side is
shorter than the left-hand-side.