util: add the code path to "cachefunc()" for the function taking no arguments
Before this patch, "util.cachefunc()" caches the value returned by the
specified function into dictionary "cache", even if the specified
function takes no arguments.
In such case, "cache" has at most one entry, and distinction between
entries in "cache" is meaningless.
This patch adds the code path to "cachefunc()" for the function taking
no arguments for efficiency: to store only one cached value, using
list "cache" is a little faster than using dictionary "cache".
$ hg init
$ mkdir alpha
$ touch alpha/one
$ mkdir beta
$ touch beta/two
$ hg add alpha/one beta/two
$ hg ci -m "start"
$ echo 1 > alpha/one
$ echo 2 > beta/two
everything
$ hg diff --nodates
diff -r 7d5ef1aea329 alpha/one
--- a/alpha/one
+++ b/alpha/one
@@ -0,0 +1,1 @@
+1
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2
beta only
$ hg diff --nodates beta
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2
inside beta
$ cd beta
$ hg diff --nodates .
diff -r 7d5ef1aea329 beta/two
--- a/beta/two
+++ b/beta/two
@@ -0,0 +1,1 @@
+2
$ cd ..