You can nest things as you like within #if. (Whitespace is not significant
in C++.)

On Tue, Dec 13, 2022 at 5:13 PM Michael Levine via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> I propose that we introduce the following new preprocessor conditional
> inclusion syntax:
>
> condexpr if (expression or identifier, expression or identifier...) {
> ....the conditional logic....
> }
>
> New keyword to reserve: condexpr
>
> Some advantages:
> - The syntax looks more like standard C++ code and less like
> preprocessor directives
> - Rather than writing the preprocessor conditional inclusion syntax like
> #ifdef and #endif at the beginning of each line, which breaks the flow of
> code if the code is already nested, this syntax can be written directly
> into the regular C++ code.
>
> Here is how I would rewrite most of the example from the Conditional
> Inclusion page here (
> https://en.cppreference.com/w/cpp/preprocessor/conditional) using this
> new syntax:
>
> #define ABCD 2#include <iostream>
> int main(){
> condexpr if (ABCD)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "1: yes\n";
>
> }else
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "1: no\n";
>
> } condexpr if (!ABCD)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "2: no1\n";
>
> }elif (ABCD == 2)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "2: yes\n";
>
> }else
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "2: no2\n";
>
> } condexpr if (!(DCBA) && (ABCD < 2*4-3))
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "3: yes\n";
>
> }
> condexpr if (CPU)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "4: no1\n";
>
> }elif (GPU)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "4: no2\n";
>
> }elif (!RAM)
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "4: yes\n";
>
> }else
>
> {
> std::cout <http://en.cppreference.com/w/cpp/io/cout> << "4: no!\n";
> }
>
>
>
> }
>
> --
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