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Guest
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erl_pp writes out try-catch clauses in a very strange
way that doesn't compile.
I was experimenting with the following test function:
generate_src_file(File, Tabs, L1) ->
Forms = codegen(Tabs, L1),
Out = [[erl_pp:form(F), "\n"] || F <- Forms],
{ok, _Mod, _Bin} = compile:forms(Forms),
{ok, Fd} = file:open(File, [write]),
io:fwrite(Fd, "~s~n", [Out]),
file:close(Fd).
The generated output compiled with a few warnings,
but when I tried compiling the file created using
erl_pp, I got a compilation error on the following:
validate_string(S,Attr,Expected) ->
try
list_to_binary(S)
of
_ ->
true
catch
error:_:_ ->
throw({type_error,Attr,{expected,Expected}})
end.
For some reason, erl_parse adds a {var, L, '_'} to the
catch clause in a try expression:
[{clause,
44,
[{tuple,
44,
[{atom,44,error},
{var,44,'_'},
{var,44,'_'}]}],
[],
[{call,
and erl_pp happily puts a colon between the first pattern
and the extra '_'.
I modified erl_pp.erl as given below (using a case statement,
since I guessed that there would be a purpose to that extra
pattern, and that it wouldn't always be '_' in the future).
Well, at least compiling the erl_pp output gave the same
result as compiling the forms (I think... - it's not that
easy to compare the results.)
/Uffe
ws12858> diff -c erl_pp.erl $OTP_ROOT/lib/stdlib-1.13.10/src/erl_pp.erl
*** erl_pp.erl Sun Dec 25 01:00:53 2005
--- OTP/lib/stdlib-1.13.10/src/erl_pp.erl Tue Oct 25 13:25:38 2005
***************
*** 466,478 ****
body(B, I+4, Hook)];
try_clause({clause,_,[{tuple,_,[C,V,S]}],G,B}, I, Hook) ->
Cs = expr(C, I, 0, Hook),
! [case S of
! {var, _, '_'} ->
! Cs, ":", expr(V, indentation(Cs, I)+1, 0, Hook);
! _ ->
! [Cs, ":", expr(V, indentation(Cs, I)+1, 0, Hook),
! ":", expr(S, indentation(Cs, I)+1, 0, Hook)]
! end,
guard(G, I, Hook),
body(B, I+4, Hook)].
--- 466,473 ----
body(B, I+4, Hook)];
try_clause({clause,_,[{tuple,_,[C,V,S]}],G,B}, I, Hook) ->
Cs = expr(C, I, 0, Hook),
! [Cs, ":", expr(V, indentation(Cs, I)+1, 0, Hook),
! ":", expr(S, indentation(Cs, I)+1, 0, Hook),
guard(G, I, Hook),
body(B, I+4, Hook)].
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