From 5bb8262bd4ae8dbcc7438e80de5cedac7ccee1af Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Tue, 31 Mar 2015 08:47:57 +0200 Subject: Raise more descriptive error messages for failed map operations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit According to EEP-43 for maps, a 'badmap' exception should be generated when an attempt is made to update non-map term such as: <<>>#{a=>42} That was not implemented in the OTP 17. José Valim suggested that we should take the opportunity to improve the errors coming from map operations: http://erlang.org/pipermail/erlang-questions/2015-February/083588.html This commit implement better errors from map operations similar to his suggestion. When a map update operation (Map#{...}) or a BIF that expects a map is given a non-map term, the exception will be: {badmap,Term} This kind of exception is similar to the {badfun,Term} exception from operations that expect a fun. When a map operation requires a key that is not present in a map, the following exception will be raised: {badkey,Key} José Valim suggested that the exception should be {badkey,Key,Map}. We decided not to do that because the map could potentially be huge and cause problems if the error propagated through links to other processes. For BIFs, it could be argued that the exceptions could be simply 'badmap' and 'badkey', because the bad map and bad key can be found in the argument list for the BIF in the stack backtrace. However, for the map update operation (Map#{...}), the bad map or bad key will not be included in the stack backtrace, so that information must be included in the exception reason itself. For consistency, the BIFs should raise the same exceptions as update operation. If more than one key is missing, it is undefined which of keys that will be reported in the {badkey,Key} exception. --- lib/stdlib/src/erl_eval.erl | 20 ++++++++------------ lib/stdlib/test/erl_eval_SUITE.erl | 5 ++++- 2 files changed, 12 insertions(+), 13 deletions(-) (limited to 'lib/stdlib') diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl index 371573dc23..e86e10b170 100644 --- a/lib/stdlib/src/erl_eval.erl +++ b/lib/stdlib/src/erl_eval.erl @@ -246,18 +246,14 @@ expr({record,_,_,Name,_}, _Bs, _Lf, _Ef, _RBs) -> %% map expr({map,_,Binding,Es}, Bs0, Lf, Ef, RBs) -> {value, Map0, Bs1} = expr(Binding, Bs0, Lf, Ef, none), - case Map0 of - #{} -> - {Vs,Bs2} = eval_map_fields(Es, Bs0, Lf, Ef), - Map1 = lists:foldl(fun ({map_assoc,K,V}, Mi) -> - maps:put(K, V, Mi); - ({map_exact,K,V}, Mi) -> - maps:update(K, V, Mi) - end, Map0, Vs), - ret_expr(Map1, merge_bindings(Bs2, Bs1), RBs); - _ -> - erlang:raise(error, {badarg,Map0}, stacktrace()) - end; + {Vs,Bs2} = eval_map_fields(Es, Bs0, Lf, Ef), + _ = maps:put(k, v, Map0), %Validate map. + Map1 = lists:foldl(fun ({map_assoc,K,V}, Mi) -> + maps:put(K, V, Mi); + ({map_exact,K,V}, Mi) -> + maps:update(K, V, Mi) + end, Map0, Vs), + ret_expr(Map1, merge_bindings(Bs2, Bs1), RBs); expr({map,_,Es}, Bs0, Lf, Ef, RBs) -> {Vs,Bs} = eval_map_fields(Es, Bs0, Lf, Ef), ret_expr(lists:foldl(fun diff --git a/lib/stdlib/test/erl_eval_SUITE.erl b/lib/stdlib/test/erl_eval_SUITE.erl index 3427f431c5..a750c5cace 100644 --- a/lib/stdlib/test/erl_eval_SUITE.erl +++ b/lib/stdlib/test/erl_eval_SUITE.erl @@ -1482,8 +1482,11 @@ eep43(Config) when is_list(Config) -> " #{ K1 := 1, K2 := 2, K3 := 3, {2,2} := 4} = Map " "end.", #{ 1 => 1, <<42:301>> => 2, {3,<<42:301>>} => 3, {2,2} => 4}), - error_check("[camembert]#{}.", {badarg,[camembert]}), + error_check("[camembert]#{}.", {badmap,[camembert]}), + error_check("[camembert]#{nonexisting:=v}.", {badmap,[camembert]}), error_check("#{} = 1.", {badmatch,1}), + error_check("[]#{a=>error(bad)}.", bad), + error_check("(#{})#{nonexisting:=value}.", {badkey,nonexisting}), ok. %% Check the string in different contexts: as is; in fun; from compiled code. -- cgit v1.2.3