macro: introduce TAKE_PTR() macro

This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.

This takes inspiration from Rust:

https://doc.rust-lang.org/std/option/enum.Option.html#method.take

and was suggested by Alan Jenkins (@sourcejedi).

It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)

1 files changed, 1 insertions, 2 deletions

diff --git a/src/basic/extract-word.c b/src/basic/extract-word.c
index 5e42560487..7a6b56f071 100644
--- a/src/basic/extract-word.c
+++ b/src/basic/extract-word.c
@@ -194,8 +194,7 @@ finish:
 
 finish_force_next:
         s[sz] = 0;
-        *ret = s;
-        s = NULL;
+        *ret = TAKE_PTR(s);
 
         return 1;
 }