Re: how to design a replacement for C++
"Keith H Duggar" <duggar@alum.mit.edu>
It's been some time since I've had the opportunity of building a large
C++ code base, but my recollection is that it took hours, even after
reducing it considerably with precompiled headers and other tweaks.
This compared with minutes for a Java code base of similar size. I
don't think this is a unique observation, and issues with build times
may be of special significance to C++ developers, as compared to other
languages.
It's also an irrelevant observation because it compares compilation
of different languages.
How could it be irrelevant? Compilation time is a practical matter, nothing
else. It a full rebuild would take just milliseconds, who would bother at
all?
As long as a full rebuild of java still takes a magnitude more than a
fine-tuned C++ system, arguments about superiority of the latter will hardly
win. ;-)
An accurate comparison is instead between
compiling a header-only implementation of some C++ versus one that
separates .hpp/.cpp. And for Java comparing the time of compiling
only the files that must be compiled due to interface changes vs
compiling all files that import the changed file even if interface
was not changed.
Possibly could make a PhD thesis and impress a some folks who only know
build from books... Not anyone from practice.
Sure. The point is that it is /possible/ to separate some and even
all (for example pure abstract functions, pimpl, etc) implementation
away from the interface. This is simply not possible in Java since
you are /forced/ to conflate implementation and interface in the
same file.
I'm light on java, but I saw people using 'interface' alot. That is
certainly pure. And does a plenty of separation too. And compiles separately
too using your terms. Is anything preventing to do all the job through
interfaces? Stating that any implementation of the interface is considered
private stuff?
Nearly anyone who has worked on large projects knows all too well
that judicious removal of code from headers (function code, pimpl,
explicit template instantiation, etc) can reduce C++ compile times
IMMENSELY. So I'm really not sure what planet you are working on.
At a really steep cost -- and leaving that immensly reduced time still
pretty high.