Hi,
And we had another day of many learnings, and building blocks for our
Hackathon on Friday!
Thank you Saifi and thank you folks who joined in!
Here's the summary from today's session:
-----
triplet
linux-glibc-gcc
x86_64 (AMD64)
Why do you we need modules in general in C++?
analysing #include statement:
g++ -E <filename>.cc > log
This would generate a long log from the pre-processor
The issue here is the C pre-processor works before the C++ compiler comes in,
what the pre-processor does is verbatim substitution or the macro hackery.
stages:
pre-processing
|
v
compiling
|
v
linking
We looked at why Macros are considered evil.
Multiple includes
Compilation
Linking
C++ modules are compiled and they have their own link, which means, Module
linking.
A full fleged Database, just casually beats elasticsearch in latency and QPS.
https://github.com/infiniflow/infinity
Written in C++ and using c++ modules.
C++ focus from day 1 has been exceptionally high performance.
The problematic thing is Cmake!
30 years of headers files, it's not going to go away. Because c++ has a very
clear cut mandate is to maintain backward compatibility. C++ maintains HU, and
the translation unit becomes a MU (module unit).
It supports both headers as header units and modules.
When working with a module unit you can #include header or import HU along with
importing a module.
import is a keyword and not a pre-processor directive like #include, and can
only be directly compiled.
import can only be used with option -fmodules-ts when compiling the .cc file.
This is a command to create a header unit:
g++ -fmodules-ts -fmodule-only -c -x c++-system-header iostream
PCH : Pre-compiled headers
Our community would use the below triplet:
linux-glibc-gcc
Demir project helps us achieve that.
References:
https://vitaut.net/posts/2024/faster-cpp-compile-times/
https://sourceforge.net/projects/softwarefreedom/files/gcc/
https://stackoverflow.com/questions/318398/why-does-c-compilation-take-so-long
-----
Please note that the screenshots from the session would be posted on the
meetup group.
Warm regards
Ragini.
