From f604f94e89a676b5f844e8d309fdbd5b55a92010 Mon Sep 17 00:00:00 2001
From: Joakim Hove <joakim.hove@gmail.com>
Date: Tue, 22 Sep 2020 10:01:53 +0200
Subject: [PATCH] Document format placeholders in KeywordLocation

---
 opm/common/OpmLog/KeywordLocation.hpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/opm/common/OpmLog/KeywordLocation.hpp b/opm/common/OpmLog/KeywordLocation.hpp
index 00f491063..13b955b8d 100644
--- a/opm/common/OpmLog/KeywordLocation.hpp
+++ b/opm/common/OpmLog/KeywordLocation.hpp
@@ -20,10 +20,25 @@
 #ifndef KEYWORD_LOCATION_HPP
 #define KEYWORD_LOCATION_HPP
 
+#include <string>
+
 namespace Opm {
 
 class KeywordLocation {
 public:
+    /*
+      Observe that many error messages whcih should print out the name of the
+      problem keyword along with the location {} placeholders can be used. The
+      convention is:
+
+         {keyword} -> keyword
+         {file} -> filename
+         {line} -> lineno
+
+      This convention must be adhered to at the call site *creating the output
+      string*.
+     */
+
     std::string keyword;
     std::string filename = "<memory string>";
     std::size_t lineno = 0;