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From: neff@Shasta.STANFORD.EDU (Randy Neff)
Newsgroups: comp.lang.ada
Subject: Ada Libraries
Message-ID: <2501@Shasta.STANFORD.EDU>
Date: 19 Feb 88 19:58:54 GMT
Reply-To: neff@Shasta.Stanford.edu (Randall Neff)
Distribution: na
Organization: Stanford University
Keywords: Ada library
List-Id: <comp.lang.ada>

Read  "Source Code" by Mark Weisner of Xerox PARC, in IEEE Computer, Nov 87.

This paper is an excellent discussion of why programmers should have reading
access to all source code.   My twenty odd years of programming experience
agrees with his arguements.   I.E. writing an Ada interface to Un*x curses
required reading the source code;  a complete Ada interface to Sun CGI 
was aborted because no source was available.

I have wasted weeks of time with buggy Ada compilers when the error 
messages (like internal assertion error 59) were meaningless.   Having the
source code and debugger would at least allow me to find out what caused
the error and how to write a work around.   No way will I fix the compiler;
it is just that the error messages and documentation are useless.

However, if a vendor wants to cripple the programmers that buy its library by
not providing source code, then here is one note:   the Verdix compiler
library has the source file name, which is used by the debugger.  
Delete or rename the source file and the debugger cannot find it.

Motherhood:   One of the big unanswered questions in CS is how to 
define the word 'guarantee' as in:  "I, the vendor, guarantee that the
specifications are complete, correct, and consistent; and that the 
hidden code I provide is complete, correct, and consistent with the 
specifications."   Unfortunately,  today's state of the art is that the
only trustworthy specification is the machine code; if you trust your
assembler, then the assembly code; if you trust your Ada compiler (I don't),
then the Ada source code.   

Randall Neff @sierra.stanford.edu