[PATCH 1/5] git-compat-util: add xstrdup_or_null helper

[Jeff King <peff@peff.net>]

It's a common idiom to duplicate a string if it is non-NULL,
or pass a literal NULL through. This is already a one-liner
in C, but you do have to repeat the name of the string
twice. So if there's a function call, you must write:

  const char *x = some_fun(...);
  return x ? xstrdup(x) : NULL;

instead of (with this patch) just:

  return xstrdup_or_null(some_fun(...));

Signed-off-by: Jeff King <peff@peff.net>
---
This example is the heart of the readability question to me. It is nice
to avoid the temporary, which makes the code more direct. But it also
sticks some_fun(...) inside another function, which is a little harder
to read.

 git-compat-util.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/git-compat-util.h b/git-compat-util.h
index dcecd85..8157eb2 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -675,6 +675,11 @@ extern char *xgetcwd(void);
 
 #define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), (alloc) * sizeof(*(x)))
 
+static inline char *xstrdup_or_null(const char *str)
+{
+	return str ? xstrdup(str) : NULL;
+}
+
 static inline size_t xsize_t(off_t len)
 {
 	if (len > (size_t) len)
-- 
2.2.1.425.g441bb3c