On 5/29/2022 11:13 PM, Paulo Pinto wrote:
Stepstone did it for Objective-C with #import,
Not the same as C doing the importing of C code.
and Apple with module maps for C
and Objective-C, the modules design that preceeded C++ modules on clang.
Then we have those failed attempts at fixing C like SafeC.
And if we count research work, Bjarne Stroustoup and Gabriel dos Reis, did it
back when they were teaching in Texas university, here is the 2009 paper,
"A Principled, Complete, and Efficient Representation of C++"
https://www.stroustrup.com/gdr-bs-macis09.pdf
Going around the horn, really doing it the hard way. Besides, writing a paper is
not the same thing as implementing a working system. There were many proposals
about adding modules to C, they just all went nowhere.
Both Visual Age for C++ v0.4 and Lucid's Energize C++ did 40 years ago, by
serializing C++ code into database representation, both failed due to high
hardware requirements for late 80's/early 90's PCs.
Yee gods, doing it with a database representation is certainly going around the
horn.
Note that neither D nor ImportC rely on some database or symbol table file.
Lucid Energize Demo in 1993
https://www.youtube.com/watch?v=pQQTScuApWk
Its database system, Cadillac,
"Foundation for a C++ Programming Environment"
https://dreamsongs.com/Files/Energize.pdf
Visual Age for C++ v4,
http://www.edm2.com/0704/vacpp4/vacpp4.html
The build environment is totally different from traditional compilers. The
concept of header files and source code files is obsolete. VAC++ utilizes a
global approach to definitions and implementations. That is, once a definition
is processed it stays in memory for the duration of the build. To maintain
compatibility, header files can still be #included. This new approach to
handling source code is disorienting at first and will make migrating existing
code to the compiler somewhat difficult. Errors pertaining to objects being
defined more than once will likely occur while migrating. Often these errors
are incorrect. The work around is to remove the #include line in the source
file that contains the offending “redefinition”.
https://books.google.de/books?id=ZwHxz0UaB54C&pg=PA206&redir_esc=y#v=onepage&q&f=false
Additionally the way pre-compiled headers work on C++ Builder and Visual C++,
versus the UNIX way, meant that on Windows the reward of the action did not
outweigh the costs incurred, and ironically Visual C++ is the one leading the
C++ modules support anyway, thanks to Gabriel dos Reis being part of the team,
and pinging back on those 2009 learnings.
Precompiled headers for C and C++ were certainly a module-like system (I know
because I wrote one), but they are horrific kludges.
