Language change proposal

[Chandrashekhar Mullaparthi]

Hi,

> -----Original Message-----
> From: Joe Armstrong [mailto:joe@REDACTED]
> Sent: 22 October 2003 12:27
> To: erlang-questions@REDACTED
> Subject: Language change proposal
> 
> 
> 
> Hi everybody - I'd like to propose the following language change:
> 
> (It's *very* easy to implement)
> 
> I want all Erlang modules to be tagged with a "language version"
> 
> Like this ...
> 
> --------------------------------------------------------------
> ----------
> 
>     Suppose the next version of Erlang is 5.3 then:
> 
> 	1) All modules *must* start
> 
> 	-module(XXXX).
> 	-vsn("5.3").

I don't know how useful this will be. Isn't it enough if we extend the
syntax of the .app file to specify this. After all, the smallest component
which is *shipped* is an application. 

{application, Application,
  [{description,  Description},
   {vsn,          Vsn},
   {id,           Id},
   {modules,      [Module1, .., ModuleN]},
   {maxT,         MaxT},
   {registered,   [Name1, .., NameN]},
   {applications, [Appl1, .., ApplN]},
   {included_applications, [Appl1, .., ApplN]},
   {env,          [{Par1, Val1}, .., {ParN, ValN}]},
   {mod,          {Module, StartArgs}},
   {start_phases, [{Phase1, PhaseArgs1}, .., {PhaseN, PhaseArgsN}]}]}.

We can include an extra tag here which specifies the version of ERTS
required. This should be optional. 

As in

   {erts_vsn,    ErtsVsn}

where ErtsVsn = {minimum, "5.3"} | {only, "5.3"} ??

The .rel file already requires that the version of ERTS be specified and is
strictly enforced when a system is being built.

In another email, you wrote:
> I also *hate* stuff that is hidden away in version control software -
> I much prefer explicit versioning in the code where I can read it -
> Stuff which is hidden in CVS/clearcase etc. often prevents a module
> from having a life of it's own outside the versioning tool ...

I can't comment about clear case, but in CVS, if the version in the module
is specified as 

-vsn('$Id: $ ').

When the code is checked in, the $Id: $ is translated to 

-vsn('$Id: dl_parse.erl,v 1.10 2003/06/19 10:58:32 chandru Exp $ ').

which is visible in dl_parse:module_info().

5> dl_parse:module_info().
[{exports,[{is_vcard,1},
           {parse_vcard,1},
           {parse_command,1},
           {many_to_rest,1},
           {module_info,0},
           {module_info,1}]},
 {imports,[]},
 {attributes,[{author,[chandru@REDACTED]},
              {vsn,['$Id: dl_parse.erl,v 1.10 2003/06/19 10:58:32 chandru
Exp $ ']}]},
 {compile,[{options,[v3]},{version,"4.1"},{time,{2003,10,23,11,54,5}}]}]

cheers
Chandru



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