From 4ca1295c44ff6f617e6250210277fdbe00ba0596 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Fri, 11 Jul 2014 23:05:13 +0200
Subject: [PATCH] CCError.fail_printf

---
 core/CCError.ml  | 6 ++++++
 core/CCError.mli | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/core/CCError.ml b/core/CCError.ml
index fe1fdd86..851cd5c1 100644
--- a/core/CCError.ml
+++ b/core/CCError.ml
@@ -43,6 +43,12 @@ let return x = `Ok x
 
 let fail s = `Error s
 
+let fail_printf format =
+  let buf = Buffer.create 16 in
+  Printf.kbprintf
+    (fun buf -> fail (Buffer.contents buf))
+    buf format
+
 let _printers = ref []
 
 let register_printer p = _printers := p :: !_printers
diff --git a/core/CCError.mli b/core/CCError.mli
index ab850d9a..d054296d 100644
--- a/core/CCError.mli
+++ b/core/CCError.mli
@@ -45,6 +45,11 @@ val fail : string -> 'a t
 
 val of_exn : exn -> 'a t
 
+val fail_printf : ('a, Buffer.t, unit, 'a t) format4 -> 'a
+(** [fail_printf format] uses [format] to obtain an error message
+    and then returns [`Error msg]
+    @since NEXT_VERSION *)
+
 val map : ('a -> 'b) -> 'a t -> 'b t
 
 val map2 : ('a -> 'b) -> (string -> string) -> 'a t -> 'b t