[erlang-questions] What is the best way to parse complex erlang terms in port drivers?

Zhemzhitsky Sergey <>
Fri Jun 8 17:15:53 CEST 2012


Hello Richard,

I'm very interested in the information and answers to the following points:

1. If there is ei API why there are no samples of how to use it here http://www.erlang.org/doc/tutorial/users_guide.html?
2. Why samples here http://www.erlang.org/doc/tutorial/erl_interface.html use ETERM API although the page is about erl interface (ei API?)?
3. I'd like to see more complex samples in the official docs, for examples how to parse a list of tagged tuples (proplist, etc.).
4. I'd like to know how to use ei API correctly. For example 
	1) ei_get_type(const char *buf, const int *index, int *type, int *size)  decodes type of the term. There is no documentation about possible values of the *type* parameter except for ei.h file.
	2) if ei_get_type returns ERL_INTEGER_EXT as a third parameter which of the following functions I have to use ei_decode_long, ei_decode_ulong, ei_decode_longlong, ei_decode_ulonglong to decode the term?
5. I'm also interested in what type of API is legal and recommended to use in c nodes, ports, port drivers. Is it possible to use ei, eterm, etc.? Is there any difference between usage of different api in c nodes, ports, port drivers?
6. I'd like see among the docs for memory, term, etc.-allocating functions information about corresponding disposing functions and whether it's necessary to call them or not.


Best Regards,
Sergey

-----Original Message-----
From: Richard O'Keefe [mailto:] 
Sent: Friday, June 08, 2012 2:43 AM
To: Zhemzhitsky Sergey
Cc: 
Subject: Re: [erlang-questions] What is the best way to parse complex erlang terms in port drivers?


On 7/06/2012, at 7:19 PM, Zhemzhitsky Sergey wrote:

> Hi Richard,
> 
> Thanks a lot for answer. It is rather helpful.
> 
>>> Why was it hard to see in the documentation?
> As I'm kinda a newbie at erlang I understand your indignation.

There was no indignation there.  There has been a lot of discussion here about documentation and what to do to improve it, and I really wanted to know what went wrong here.

Would it be sufficient to have a document "Exchanging data between Erlang and C : Overview"
with links between it and the libraries?

What would you like to see in examples?


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