Driver question

Sean Hinde Sean.Hinde@REDACTED
Wed Aug 22 00:02:37 CEST 2001


>     I would like to do sone parsing of data. What is the best 
> way to do this? I
> have an integer and I would like to make sure that is is a 
> particular length
> and that it is comprised entirly of digits. I have looked at 
> io_lib and a
> number of other spots but havent really found anything too 
> elegant.  Everything
> seems to involve converting to strings or using large 
> function gaurds. If this
> is the way to go I will, but if anyone has a better idea I 
> would like to know.
> I am always parsing packets in erlang so any info on that in 
> general would be
> nice.

I'm not sure quite what you are getting at here. If it is an integer then I
don't see how it can contain anything other than digits. If you have it as a
list (e.g [0,0,1,2,3]) the best solution I have come up with is to convert
it to ascii representation and use the BIF list_to_integer("00123"). I agree
it isn't really that pretty.

For just about every other kind of packet parsing the bit syntax is just too
cool for words.

>     I have an application running that emails the interested 
> parties when it
> goes down. I have accomplished this in a way that I think is 
> rather kludgy. I
> use a linked process that traps exit signals from my main 
> supervisor. I was
> wondering if there is a call back that is called during the 
> shutdown sequence
> of the app that I could use to make sure that the email is 
> sent on the death of
> the app.

We usually send out an SNMP trap when apps die. There is a callback provided
for exactly this in the standard application template provided in the emacs
mode (included below).



%%-export([Function/Arity, ...]).


%% application callbacks
-export([start/2, stop/1]).

%%% Callback functions from application

%% Func: start/2
%% Returns: {ok, Pid}        |
%%          {ok, Pid, State} |
%%          {error, Reason}   
start(Type, StartArgs) ->
    case 'TopSupervisor':start_link(StartArgs) of
	{ok, Pid} -> 
	    {ok, Pid};
	Error ->

%% Func: stop/1
%% Returns: any 
stop(State) ->

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