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authorBjörn Gustavsson <[email protected]>2010-04-09 15:50:17 +0200
committerBjörn Gustavsson <[email protected]>2011-11-07 13:57:03 +0100
commitff432e262e65243cbc983fcb002527f8fae8c78b (patch)
tree1966b14f94663375eb0333c3e2d707aab501a960 /lib/compiler/src/sys_pre_expand.erl
parent33c08d87a9395ae088eebcad9fb62193d26b6846 (diff)
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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
Diffstat (limited to 'lib/compiler/src/sys_pre_expand.erl')
-rw-r--r--lib/compiler/src/sys_pre_expand.erl11
1 files changed, 8 insertions, 3 deletions
diff --git a/lib/compiler/src/sys_pre_expand.erl b/lib/compiler/src/sys_pre_expand.erl
index 0fa1fea09f..7facbafb6d 100644
--- a/lib/compiler/src/sys_pre_expand.erl
+++ b/lib/compiler/src/sys_pre_expand.erl
@@ -554,9 +554,14 @@ fun_tq(Lf, {function,F,A}=Function, St0) ->
{{'fun',Lf,Function,{Index,Uniq,Fname}},
St2#expand{fun_index=Index+1}}
end;
-fun_tq(L, {function,M,F,A}, St) ->
- {{call,L,{remote,L,{atom,L,erlang},{atom,L,make_fun}},
- [{atom,L,M},{atom,L,F},{integer,L,A}]},St};
+fun_tq(L, {function,M,F,A}, St) when is_atom(M), is_atom(F), is_integer(A) ->
+ %% This is the old format for external funs, generated by a pre-R15
+ %% compiler. That means that a tool, such as the debugger or xref,
+ %% directly invoked this module with the abstract code from a
+ %% pre-R15 BEAM file. Be helpful, and translate it to the new format.
+ fun_tq(L, {function,{atom,L,M},{atom,L,F},{integer,L,A}}, St);
+fun_tq(Lf, {function,_,_,_}=ExtFun, St) ->
+ {{'fun',Lf,ExtFun},St};
fun_tq(Lf, {clauses,Cs0}, St0) ->
Uniq = erlang:hash(Cs0, (1 bsl 27)-1),
{Cs1,St1} = fun_clauses(Cs0, St0),