From 0edb6a4d2d76960846fd04ecce3aa00b3348691b Mon Sep 17 00:00:00 2001 From: Stavros Aronis Date: Sun, 30 May 2010 20:02:39 +0300 Subject: Add '-callback' attribute to language syntax Behaviours may define specs for their callbacks using the familiar spec syntax, replacing the '-spec' keyword with '-callback'. Simple lint checks are performed to ensure that no callbacks are defined twice and all types referred are declared. These attributes can be then used by tools to provide documentation to the behaviour or find discrepancies in the callback definitions in the callback module. --- lib/stdlib/src/erl_parse.yrl | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'lib/stdlib/src/erl_parse.yrl') diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl index bd5d65a1e1..709bd83e6f 100644 --- a/lib/stdlib/src/erl_parse.yrl +++ b/lib/stdlib/src/erl_parse.yrl @@ -62,7 +62,7 @@ char integer float atom string var '==' '/=' '=<' '<' '>=' '>' '=:=' '=/=' '<=' '<<' '>>' '!' '=' '::' '..' '...' -'spec' % helper +'spec' 'callback' % helper dot. Expect 2. @@ -77,6 +77,7 @@ attribute -> '-' atom attr_val : build_attribute('$2', '$3'). attribute -> '-' atom typed_attr_val : build_typed_attribute('$2','$3'). attribute -> '-' atom '(' typed_attr_val ')' : build_typed_attribute('$2','$4'). attribute -> '-' 'spec' type_spec : build_type_spec('$2', '$3'). +attribute -> '-' 'callback' type_spec : build_type_spec('$2', '$3'). type_spec -> spec_fun type_sigs : {'$1', '$2'}. type_spec -> '(' spec_fun type_sigs ')' : {'$2', '$3'}. @@ -549,6 +550,8 @@ Erlang code. ErrorInfo :: error_info(). parse_form([{'-',L1},{atom,L2,spec}|Tokens]) -> parse([{'-',L1},{'spec',L2}|Tokens]); +parse_form([{'-',L1},{atom,L2,callback}|Tokens]) -> + parse([{'-',L1},{'callback',L2}|Tokens]); parse_form(Tokens) -> parse(Tokens). @@ -603,7 +606,8 @@ build_typed_attribute({atom,La,Attr},_) -> _ -> ret_err(La, "bad attribute") end. -build_type_spec({spec,La}, {SpecFun, TypeSpecs}) -> +build_type_spec({Kind,La}, {SpecFun, TypeSpecs}) + when (Kind =:= spec) or (Kind =:= callback) -> NewSpecFun = case SpecFun of {atom, _, Fun} -> @@ -617,7 +621,7 @@ build_type_spec({spec,La}, {SpecFun, TypeSpecs}) -> %% Old style spec. Allow this for now. {Mod,Fun,Arity} end, - {attribute,La,spec,{NewSpecFun, TypeSpecs}}. + {attribute,La,Kind,{NewSpecFun, TypeSpecs}}. find_arity_from_specs([Spec|_]) -> %% Use the first spec to find the arity. If all are not the same, -- cgit v1.2.3 From ff432e262e65243cbc983fcb002527f8fae8c78b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Fri, 9 Apr 2010 15:50:17 +0200 Subject: EEP-23: Allow variables in fun M:F/A Currently, the external fun syntax "fun M:F/A" only supports literals. That is, "fun lists:reverse/1" is allowed but not "fun M:F/A". In many real-life situations, some or all of M, F, A are not known until run-time, and one is forced to either use the undocumented erlang:make_fun/3 BIF or to use a "tuple fun" (which is deprecated). EEP-23 suggests that the parser (erl_parse) should immediately transform "fun M:F/A" to "erlang:make_fun(M, F, A)". We have not followed that approach in this implementation, because we want the abstract code to mirror the source code as closely as possible, and we also consider erlang:make_fun/3 to be an implementation detail that we might want to remove in the future. Instead, we will change the abstract format for "fun M:F/A" (in a way that is not backwards compatible), and while we are at it, we will move the translation from "fun M:F/A" to "erlang:make_fun(M, F, A)" from sys_pre_expand down to the v3_core pass. We will also update the debugger and xref to use the new format. We did consider making the abstract format backward compatible if no variables were used in the fun, but decided against it. Keeping it backward compatible would mean that there would be different abstract formats for the no-variable and variable case, and tools would have to handle both formats, probably forever. Reference: http://www.erlang.org/eeps/eep-0023.html --- lib/stdlib/src/erl_parse.yrl | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'lib/stdlib/src/erl_parse.yrl') diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl index 709bd83e6f..928c10f7f2 100644 --- a/lib/stdlib/src/erl_parse.yrl +++ b/lib/stdlib/src/erl_parse.yrl @@ -35,7 +35,7 @@ tuple %struct record_expr record_tuple record_field record_fields if_expr if_clause if_clauses case_expr cr_clause cr_clauses receive_expr -fun_expr fun_clause fun_clauses +fun_expr fun_clause fun_clauses atom_or_var integer_or_var try_expr try_catch try_clause try_clauses query_expr function_call argument_list exprs guard @@ -395,11 +395,17 @@ receive_expr -> 'receive' cr_clauses 'after' expr clause_body 'end' : fun_expr -> 'fun' atom '/' integer : {'fun',?line('$1'),{function,element(3, '$2'),element(3, '$4')}}. -fun_expr -> 'fun' atom ':' atom '/' integer : - {'fun',?line('$1'),{function,element(3, '$2'),element(3, '$4'),element(3,'$6')}}. +fun_expr -> 'fun' atom_or_var ':' atom_or_var '/' integer_or_var : + {'fun',?line('$1'),{function,'$2','$4','$6'}}. fun_expr -> 'fun' fun_clauses 'end' : build_fun(?line('$1'), '$2'). +atom_or_var -> atom : '$1'. +atom_or_var -> var : '$1'. + +integer_or_var -> integer : '$1'. +integer_or_var -> var : '$1'. + fun_clauses -> fun_clause : ['$1']. fun_clauses -> fun_clause ';' fun_clauses : ['$1' | '$3']. -- cgit v1.2.3