[erlang-questions] (Newbie) extracting value for one key
Brian Candler
B.Candler@REDACTED
Tue Aug 19 14:18:32 CEST 2008
In Erlang, it seems a list of {key,value} tuples is often returned, e.g.
17> P = process_info(self()).
[{current_function,{erl_eval,do_apply,5}},
{initial_call,{erlang,apply,2}},
{status,running},
{message_queue_len,0},
{messages,[]},
{links,[<0.25.0>]},
{dictionary,[]},
{trap_exit,false},
{error_handler,error_handler},
{priority,normal},
{group_leader,<0.24.0>},
{heap_size,610},
{stack_size,28},
{reductions,526},
{garbage_collection,[{fullsweep_after,65535}]}]
Question: What's the idiomatic way to extract the value for a particular
key? For example, to extract "stack_size" from the above I could write
18> hd([ V || {stack_size,V} <- P ]).
28
but is there a better way to do this?
Thanks,
Brian.
P.S. I found the example at
http://www.erlang.org/doc/programming_examples/list_comprehensions.html#3.6
which shows how to factor the comprehension into a function.
I also found "element(2, element(2, lists:keysearch(stack_size, 1, P)))."
but that's rather verbose.
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