Re: Library model in Ada. was Re: Difference between ADA and c++

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Nasser says

<<Now, I was reading this below, from the above paper:

"1) Separate Compilation and Library Management

   Ada: An Ada compiler is required to enforce consistency and
strong type checking across separate compilation.  The concept of
                                                   ^^^^^^^^^^^^^^
a program library is built into the language, based on separately
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
compilable modules called "library units" whose names are part of
a hierarchical name space."

GNAT, probably the most popular Ada95 compiler, does NOT use the
program library model, but uses the code-source model, i.e. the
traditional model.

So, what going on here? who is wrong, and who is right?>>



The quoted sentence is somewhat historical at this stage, but if you
take a sufficiently abstract view of what a library is (note that the
Ada 95 reference manual substitutes the term "compilation environment",
for this term), then the statement is in fact accurate.

The big change in Ada 95 is to make it much clearer that the library
(compilation environment) is an implementatoin depenbdent abstract
concept, not some kind of file or collections of files (necessarily).

The GNAT source approach (now used by other compilers, including
those that use the Intermetrics front end), does in fact conform
with the requirements in Ada 83, although one needs to be a bit
more imaginative in reading the Ada 83 RM.

Certainly in terms of the differences between Ada and C++, the point
made in the quoted section is 100% valid and important.