[erlang-questions] Return [Value] of erlang dict:find fetch
Bengt Kleberg
bengt.kleberg@REDACTED
Thu Nov 28 11:15:37 CET 2013
These are opinions, not facts.
It is better to err on the side of caution. Some readers of
Erlang-questions are _very_ sensitive to not separating facts from
opinions.
Presumably they have only ever seen a part of the Internet where this
http://xkcd.com/386/ makes no sense.
bengt
On Thu, 2013-11-28 at 11:06 +0100, Robert Virding wrote:
> No, they are facts. :-) The documentation of dict:append says:
>
> "This function appends a new Value to the current list of values
> associated with Key."
>
>
> So it manages a list of values.
>
>
> Robert
>
>
>
> On 25 November 2013 09:02, Bengt Kleberg <bengt.kleberg@REDACTED>
> wrote:
> These are opinions, not facts.
>
> dict:append/3 creates a list of values. Try calling it several
> times and
> you will see.
> If you only want one value use dict:store/3.
>
>
> bengt
>
> On Mon, 2013-11-25 at 15:38 +0800, 王靖易 wrote:
> > Hi,
> > I'm a beginner of erlang and have found some problems in my
> project.
> > After doing some google I found here and wish someone could
> help me.
> > I'm using the erlang structure 'dict' for a key-value
> table in my
> > program, but I found that the return value of dict:fetch and
> dict:find
> > is actually [Value] or {ok, [Value]} (means I get a list
> containing
> > the value instead of the original one). However, this is not
> the
> > problem, the real problem is, this happens only in some
> situations
> > which I can't find what it is.
> > An example:
> > Eshell V5.8.5 (abort with ^G)
> > 1> A = dict:new().
> > {dict,0,16,16,8,80,48,
> > {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
> > {{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]}}}
> > 2> A2 = dict:append(key, value, A).
> > {dict,1,16,16,8,80,48,
> > {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
> > {{[],[],[],[],[],[],[],[],[],
> > [[key,value]],
> > [],[],[],[],[],[]}}}
> > 3> dict:find(key, A2).
> > {ok,[value]}
> >
> >
> > My erlang environment is R14B04 on ubuntu 12.04. Could
> any one tell
> > me why the return value of dict:find is not the same as the
> doc?
> >
> >
> > Best regards,
> > Jingyi Wang
>
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