From 9a577df2e0312e166f38bc61dbeccd37256d9eac Mon Sep 17 00:00:00 2001
From: Andrew Thompson <andrew@hijacked.us>
Date: Mon, 29 Aug 2011 14:13:40 -0400
Subject: [PATCH] Use the io_lib_format:fwrite_g function to print floats

This is superior to float_to_list as it only prints the meaningful
digits and 1.0 isn't rendered as "1.00000000000000000000e+00".
---
 src/lager_trunc_io.erl | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/lager_trunc_io.erl b/src/lager_trunc_io.erl
index 0a682b4..9d78e52 100644
--- a/src/lager_trunc_io.erl
+++ b/src/lager_trunc_io.erl
@@ -232,7 +232,9 @@ print(Binary, Max) when is_binary(Binary) ->
     {["<<", L, ">>"], Len+4};
 
 print(Float, _Max) when is_float(Float) ->
-    L = float_to_list(Float),
+    %% use the same function io_lib:format uses to print floats
+    %% float_to_list is way too verbose.
+    L = io_lib_format:fwrite_g(Float),
     {L, length(L)};
 
 print(Fun, Max) when is_function(Fun) ->
@@ -410,4 +412,20 @@ format_test() ->
     ?assertEqual("[\"foo\",98,97,114]", lists:flatten(format("~10W", [["foo", $b, $a, $r], 10], 50))),
     ok.
 
+atom_quoting_test() ->
+    ?assertEqual("hello", lists:flatten(format("~p", [hello], 50))),
+    ?assertEqual("'hello world'", lists:flatten(format("~p", ['hello world'], 50))),
+    ?assertEqual("hello_world", lists:flatten(format("~p", ['hello_world'], 50))),
+    ?assertEqual("'node@127.0.0.1'", lists:flatten(format("~p", ['node@127.0.0.1'], 50))),
+    ?assertEqual("node@nohost", lists:flatten(format("~p", [node@nohost], 50))),
+    ok.
+
+sane_float_printing_test() ->
+    ?assertEqual("1.0", lists:flatten(format("~p", [1.0], 50))),
+    ?assertEqual("1.23456789", lists:flatten(format("~p", [1.23456789], 50))),
+    ?assertEqual("1.23456789", lists:flatten(format("~p", [1.234567890], 50))),
+    ?assertEqual("0.3333333333333333", lists:flatten(format("~p", [1/3], 50))),
+    ?assertEqual("0.1234567", lists:flatten(format("~p", [0.1234567], 50))),
+    ok.
+
 -endif.