[erlang-patches] [patch] binary to/from integer

Serge Aleynikov <>
Thu Jan 10 23:32:25 CET 2013


This is exactly what Björn-Egil was talking about below ("Does
erlang:integer_to_binary(102341) mean <<0,1,143,197>> or <<"102341">>").

I can think of two other alternatives:

binary:integer_to_binstring/1 & binary:binstring_to_integer/1
binary:integer_to_text/1 & binary:text_to_integer/1

On 1/10/2013 5:13 PM, Bob Ippolito wrote:
> The purpose of integer_to_binary still isn't totally obvious from the
> name or output type, maybe it's digits, maybe it's the big endian
> encoding of that integer (which is closer to the behavior of
> binary_to_term / term_to_binary). For the more seasoned Erlang
> developer, I think they would expect it to behave like
> integer_to_string, but what about newer users?
> 
> 
> 
> On Thu, Jan 10, 2013 at 2:05 PM, Loïc Hoguin <
> <mailto:>> wrote:
> 
>     binary:integer_to_string/1 is hardly intuitive. Especially if you
>     write it like this:
> 
>     Module = binary,
>     %% ...
>     Module:integer_to_string(123)
> 
>     Do you get a binary() or a string()?
> 
>     If you create a function type1_to_type2 it's much better if type1
>     and type2 correspond to actual types.
> 
>     Wherever you place it I don't think it should be named anything
>     other than integer_to_binary. However it should be autoimported,
>     because writing integer_to_binary first and then remembering the
>     function doesn't exist is what many of us do regularly. We already
>     have the reflex, we only miss the call to be available.
> 
> 
>     On 01/10/2013 08:31 PM, Serge Aleynikov wrote:
> 
>         Thanks for the explanation!  The API naming is a headache indeed.
> 
>         It does make sense to define these functions in the binary module.
>         Though while binary:string_to_integer/1 is intuitive, I think
>         binary:integer_to_string/1 would be a more intuitive name than
>         binary:string_from_integer/1 (this also would be more consistent
>         with
>         binary:{bin,list}_to_{list,__bin}.
> 
>         On 1/10/2013 1:50 PM, Björn-Egil Dahlberg wrote:
> 
>             On 2013-01-10 18:55, Serge Aleynikov wrote:
> 
>                 I was under impression that Lucas would take care of
>                 modifications he
>                 proposed in the thread you quoted.  Meanwhile I'll see
>                 if I can find
>                 time to do this.
> 
>             I think the key words were "if it gets prioritized"  =)
>             Granted, we could be more clear on intention. I think in
>             this case we
>             supposedly had time which drastically changed at some point ..
> 
> 
>                 Do you already have an implementation of binary <->
>                 integer?  If not,
>                 maybe I could look at that one as well when I poke
>                 around the BIFs,
>                 since this is also something very commonly needed.
> 
>             Right, what I did was to take the list conversions to
>             integer and made
>             it binary comprehensible.
> 
>             That was the easy bit.
> 
>             However,
>             Now I have
>               * erlang:binary_to_integer/1 and
>               * erlang:integer_to_binary/1
>             which seems fine. The compiler will auto-import them as well.
> 
>             After I did that I began to reconsider this choice. Perhaps
>             it should be
> 
>             * binary:to_integer/1 and binary:from_integer/1 instead? Or,
>             * binary:string_from_integer/1 and binary:string_to_integer/1,
>             emphasizing that this is a textual representation of integer
>             in binary
>             format. Then I got a headache.
> 
>             The arguments for the first one (current) is:
>             * list_to_integer has same type of ideas, same type of
>             behavior. Avoids
>             confusion.
>             The arguments against the first one,
>             * Clutters the erlang module with yet more BIF's
>             * We already have a binary module, let's use it!
>             * And finally: avoid confusion! Does
>             erlang:integer_to_binary(__102341)
>             mean <<0,1,143,197>> or <<"102341">> ?
> 
>             I'm leaning towards the latter.
> 
>             Also, I didn't implement base conversion, so that needs
>             doing. I think
>             the list conversion is done in Erlang which seems backwards.
> 
>             Anyways, the current implementation is at:
>             https://github.com/psyeugenic/__otp/commits/egil/r16/binary___to_integer
>             <https://github.com/psyeugenic/otp/commits/egil/r16/binary_to_integer>
> 
>             But the real work is taking a position on the API and
>             consider the
>             different ramifications. I still have that headache ..
> 
>             Yet another also, perhaps this implementation isn't the way
>             to go. From
>             what I remember erlang:binary_to_integer didn't have the
>             speedup I first
>             envisioned. Ofc, it was faster than doing
>             binary_to_list(list_to___integer(X)) but binary_to_integer
>             was on par with
>             this list_to_integer .. which seemed a bit off.
> 
>             I want to refrain from using strtol directly (I think that
>             implementation is similar anyways and we still need to
>             handle bignums).
> 
>             I think I want to change the current implementation to
>             taking the base
>             as argument to the BIF and perhaps using arity one function
>             as an erlang
>             wrapper. (And doing the same for list_to_integer). The
>             arguments against
>             that is, surely the arity one functions is far more used and
>             it should
>             be slightly faster to that call directly.
> 
>             // Björn-Egil
> 
> 
>                 On 1/10/2013 12:41 PM, Björn-Egil Dahlberg wrote:
> 
>                     On 2013-01-10 18:08, Serge Aleynikov wrote:
> 
>                         Not quite - in two days my "new float_to_list/2"
>                         patch is celebrating
>                         its 2 year anniversary sitting in the awaiting
>                         mode.  ;-)
> 
>                     Nice =o
>                     However, it is not really as you imply. A simple
>                     patch that has been
>                     ignored for two years =)
> 
>                     I checked in Monitor/OTP:
>                     * sal/float_to_list_2
>                     * status: unassigned
>                     * location: limbo (not present in any active backlog)
>                     * notes: waiting for response from author (noted by
>                     Lukas)
> 
>                     Lukas is currently on a mountain somewhere in south
>                     america so I can't
>                     really ask him about it.
> 
>                     As I recall, your patch had some controversy about
>                     precision?
> 
>                     And the last mail conversation mention something
>                     about modifications
>                     needed and if we were to do it we had to prioritize
>                     it along with
>                     already planned work. Needless to say, it hasn't
>                     been prioritized.
> 
>                     http://erlang.org/pipermail/__erlang-patches/2012-August/__002980.html
>                     <http://erlang.org/pipermail/erlang-patches/2012-August/002980.html>
> 
>                     Personally trying to find time to get binary (text)
>                     <-> integer
>                     conversions into the backlog.
> 
>                     Being realistic, neither your float conversion nor
>                     mine will make it to
>                     r16. *sadface*
> 
> 
>                     // Björn-Egil
> 
>                         On 1/10/2013 10:51 AM, Max Lapshin wrote:
> 
>                             Serge, you seems to be a fast way to pull
>                             patch into upstream =)
> 
> 
>                             On Thu, Jan 10, 2013 at 7:24 PM, Serge
>                             Aleynikov <
>                             <mailto:>
>                             <mailto:
>                             <mailto:>>> wrote:
> 
>                                    That was the fastest acceptance of a
>                             patch I ever submitted.
>                             ;-)
> 
>                                    On 1/10/2013 10:03 AM, Fredrik wrote:
>                                    > Hello Serge,
>                                    > Your patch is now in the
>                             'master-pu' branch.
>                                    > Thanks for your contribution!
>                                    >
>                                    > BR Fredrik Gustafsson
>                                    > Erlang OTP Team
>                                    > On 01/10/2013 03:31 PM, Serge
>                             Aleynikov wrote:
>                                    >> Added an application:get_env/3
>                             function variant that
>                             provides a
>                                    default
>                                    >> value for a configuration parameter:
>                                    >>
>                                    >>     application:get_env(App, Key,
>                             Default) ->  Value.
>                                    >>
>                                    >> git fetch
>                             git://github.com/saleyn/otp.__git
>                             <http://github.com/saleyn/otp.git>
>                                    <http://github.com/saleyn/otp.__git
>                             <http://github.com/saleyn/otp.git>> get_env
>                                    >>
>                                    >>
>                             https://github.com/saleyn/otp/__compare/erlang:master...get___env
>                             <https://github.com/saleyn/otp/compare/erlang:master...get_env>
>                                    >>
>                             https://github.com/saleyn/otp/__compare/erlang:master...get___env.patch
>                             <https://github.com/saleyn/otp/compare/erlang:master...get_env.patch>
>                                    >>
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> 
>     -- 
>     Loïc Hoguin
>     Erlang Cowboy
>     Nine Nines
>     http://ninenines.eu
> 
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