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<  Yaws mailing list  ~  It looks like a string, it barks like a string
Guest
Posted: Mon May 05, 2008 9:46 pm Reply with quote
Guest
When trying to parse the parameters to a Form with action=POST I run into this strange behaviour:



crew(Arg, N) ->
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Guest
Posted: Mon May 05, 2008 11:16 pm Reply with quote
Guest
On 5/5/08, Guido Witmond <guido@witmond.nl> wrote:
> When trying to parse the parameters to a Form with action=POST I run into
> this strange behaviour:
>
> crew(Arg, N) ->
> % Name = f("crew_~B", [N]),
> Name = lists:concat(io_lib:format("~s~B",
> ["crew_",N])),
>
> case yaws_api:getvar(Arg, Name) of
> {ok, Member} -> #crewmember{naam = Member};
> _ -> Name
> end.
>
> My initial guess was to generate key names with f(...) but that lead to this
> output where the case matches the _ clause and it shows up as
> [[99,114,101,119,95,"1"],
> [99,114,101,119,95,"2"]
>
> When I use the lists:concat it does match the {ok, Member} clause. It gives
> the expected:
> [{crewmember,"jan",undefined},
> {crewmember,"piet",undefined},
>
> What is going on here? When is a string a string?

io_lib:format() returns an iolist, not a string, and f() simply wraps
io_lib:format() so it also returns an iolist. You can wrap either with
a call to lists:flatten to get a string:

lists:flatten(io_lib:format("~s~B", ["crew_",N]))

--steve

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