[erlang-questions] Function to print a record with fieldnames ?

[Convey Christian J NPRI]

Thanks Mats,

That works great for me.

Could you explain something to me please? :

Why must this be a macro rather than a function?  It seems that if I want rec_info to be a function rather than a macro, record_info's second parameter must be a hard-coded atom; it cannot be a variable.  But nothing I've read in Armstrong's book led me to think that such a restriction was possible in Erlang.

Thanks,
Christian

> -----Original Message-----
> From: Mats Cronqvist [mailto:mats.cronqvist@REDACTED] 
> Sent: Tuesday, March 04, 2008 9:53 AM
> To: Convey Christian J NPRI
> Cc: erlang-questions@REDACTED
> Subject: Re: [erlang-questions] Function to print a record 
> with fieldnames?
> 
> Convey Christian J NPRI wrote:
> > I've got a record definition along the lines of:  
> -record(myrec, {foo = undefined, bar=undefined}).
> >
> > To help with debugging, I'd like a function that will print 
> out something like the following text:
> >    #record{foo = 42, bar = the_answer_to_the_question}
> >
> > Does such a function exist, or must I write my own version 
> of the function for each record type?  I know I can just use 
> io:format("~p~n", [ MyRecord ]), but I'd really like the 
> fieldnames to also be printed.
> >   
>  best i've seen is variations on this theme;
> 
> -module('foo').
> -author('Mats Cronqvist').
> -export([go/0]).
> 
> -define(rec_info(T,R),lists:zip(record_info(fields,T),tl(tuple
> _to_list(R)))).
> -record(r,{bla,foo,baz,bar}).
> 
> go() -> ?rec_info(r,#r{}).
> 
> 
>