Re: [libnftables PATCH 4/6] internal: add a selector for parsing ops

[Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>]

On 8 January 2014 00:29, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> You should pass a callback function instead, eg.
>
> static int nft_chain_json_parse(struct nft_chain *c, const char *json,
>                                 struct nft_parse_err *err,
>                                 json_t *(*jsonbuilder)(const void *input_data,
>                                                        const char *treename,
>                                                        struct nft_parse_err *e))

Ok.

> But I don't understand yet what you save (in terms of lines of code)
> by using this aproach.

I avoid doing something like:

nft_*_parse() {
switch (type)
 if XML return xml_parse()
 if JSON return json_parse()
}

nft_*_parse_file() {
switch (type)
 if XML return xml_parse_file()
 if JSON return json_parse_file()
}

We double the format switch, and also two functions per format are
needed to do build and parsing.
Total = 6 functions heavily duplicating code.

With my approach, we have 1 function that decides which format to
parse, and a one function per format to build and do parsing.
Total = 3 functions, no duplicate code.
-- 
Arturo Borrero González
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