[erlang-questions] How to get the line number of current executable code?

[Edwin Fine]

Ulf,

On second thoughts, although that IS very cool, it would likely be very
expensive because it generates and catches an exception. This would matter
if it is used to do a lot of logging (which is what I would use it for).
What I really would like is a compile-time constant (pre-processor macro). I
suppose one could hack epp...?

Ed

On Fri, Aug 15, 2008 at 5:06 PM, Ulf Wiger <ulf@REDACTED> wrote:

> Why sure, you just do this:
>
> -module(m).
> -export([f/0]).
>
> -define(FUNCTION, hd(element(2,element(2,catch erlang:error([]))))).
>
> f() ->
>  {current_function, ?FUNCTION}.
>
>
>
> Eshell V5.5.4  (abort with ^G)
> 1> c(m).
> {ok,m}
> 2> m:f().
> {current_function,{m,f,0}}
> 3>
>
> BR,
> Ulf W  ;-)
>
> 2008/8/15 Edwin Fine <erlang-questions_efine@REDACTED>:
> > Something I've wished for in numerous languages over the years is a macro
> > that expands to the current function, something like ?MODULE. I don't
> > suppose there is one lurking somewhere in Erlang...?
> >
> > 2008/8/15 Matt Williamson <dawsdesign@REDACTED>
> >>
> >> You should trust the macro. It must use a similar method to Python's
> >> because they are both compiled to bytecode and thus there wouldn't
> *really*
> >> be line numbers in either one.
> >>
> >> 2008/8/15 devdoer bird <devdoer2@REDACTED>
> >>>
> >>> Thanks.
> >>>
> >>> How can I do this without macro? I know python supply some tools to
> >>> determine the line number in run time,like inspect module.
> >>>
> >>>
> >>> 2008/8/16, Anders Nygren <anders.nygren@REDACTED>:
> >>>>
> >>>> 2008/8/15 devdoer bird <devdoer2@REDACTED>:
> >>>> > HI:
> >>>> >
> >>>> > I want to implement a function like "get_current_lineno()/0" to get
> >>>> > the
> >>>> > current line number of the calling point?
> >>>> > Eg.
> >>>> > .....
> >>>> > ....
> >>>> > io:format("current line is ~w\n",[get_current_lineno()])
> >>>> > .....
> >>>> >
> >>>> > the above code will print the line number of the calling point in
> the
> >>>> > source
> >>>> > file.
> >>>> >
> >>>> > How can I do this  in erlang?
> >>>>
> >>>> There is a predefined macro ?LINE that does that
> >>>> so
> >>>> io:format("current line is ~w\n",[?LINE])
> >>>>
> >>>> /Anders
> >>>>
> >>>> > _______________________________________________
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> >>>
> >>>
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> >>
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> >
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> >
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-- 
For every expert there is an equal and opposite expert - Arthur C. Clarke
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