Re: Compiling and linking code from different places in the file system

From	James Harris <james.harris.1@gmail.com>
Newsgroups	comp.lang.misc, comp.lang.c
Subject	Re: Compiling and linking code from different places in the file system
Date	2018-03-02 21:05 +0000
Organization	A noiseless patient Spider
Message-ID	<p7ceab$f4e$1@dont-email.me> (permalink)
References	<p793c8$7d8$1@dont-email.me> <tvUlC.3079$LD5.550@fx07.am4>

Cross-posted to 2 groups.

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On 01/03/2018 14:55, bartc wrote:
> On 01/03/2018 14:40, James Harris wrote:
>>
>> It is normal in C programming for any source file which exports
>> identifiers to have an associated header file which /describes/ the
>> identifiers the source exports. For example, in a folder called PP then
>> the two files might be named
>>
>>     PP/SS.c  (the source)
>>     PP/SS.h  (the header describing SS.c's exports)
>>
>> When another source file, say UU.c, imports an identifier that SS.c
>> exports it would naturally contain a statement which brings in the
>> header at compile time.
>>
>>     UU.c
>>       #include "SS.h"
>>
>> Because C has no concept of a hierarchical namespace here, i.e. the
>> source file cannot say "include PP/SS.h" or "include SS.h from folder
>> PP", the compiler has to be told about folder PP so it looks in it for
>> the header.
> 
> C doesn't have module namespaces, but that doesn't stop you using file
> paths for an include file. So you can say:
> 
>     #include "PP/SS.h"

Yes, I forgot about that. My query was meant to be about the principle 
rather than C per se.

If one thinks of each folder as a namespace (reasons below), the query 
is about how to tell a compiler which namespaces to search in order to 
find #include targets. They would probably normally be specified on the 
command line with a -I or the like, but an environment variable 
containing the list would do just as well if that's how a certain 
compiler worked. The problem is not how to tell the compiler (strictly, 
the preprocessor) about them but about how to know which namespaces to 
use for any particular invocation of the compiler.

Best I can think of so far is to have a configuration file or files 
which uses wildcards to say which namespaces to use for each source 
file. The wildcards would be there to avoid specifying a list for each 
file individually.

For example, assuming that the namespaces to search have already been 
defined as nss[N] for various N, a configuration file could include the 
following lines.

   folder1/folder1.1/source.c nss[0]
   folder1/folder1.1/* nss[1]
   folder1/* [nss2]
   * nss[3]

That's intended to say that source.c should be compiled with the 
namespaces mentioned in nss[0], that other sources in folder1.1 should 
be compiled with nss[1], and so on.

Does that make sense? Am I missing an easier way?

Another issue is whether there should be one such configuration file per 
'project' or whether it ought to be possible to have configuration files 
in subfolders supplying info about them and folders lower down in the tree.

> 
> Although this will likely be taken to mean "./PP/SS.h". If the 'current
> source file' is already in "/PP", then that might mean "/PP/PP/SS.h".
> 
> Which brings up another point, in that the algorithm for working out
> where to look for an include file, given:
> 
>    * The set of Include paths specified to the compiler
>    * Whether this is a <...> or "..." file specifier
>    * The location of the 'current source file' (which can be an existing
>      deeply nested include file, and can involve a stack)
>    * Whether the specified path is relative or absolute (within the
>      #include directive; don't forget the -I options to the compiler
>      can also be relative or absolute)
> 
> can get complicated. And I believe is 'implementation defined'.
> 
> So it can become a bit of a nightmare, as you go on to suggest. (One
> file accidentally gets deleted, but the search algorithm finds another
> of the same name, sufficiently similar to allow the program to be
> compiled - wrongly.)

On that, I think that to do this properly there may be a need for what 
you might call "namespace algebra"! Specifically, there may be a need 
for two ways to combine namespaces:

1. Names must be unique - i.e. no duplicates in another namespace.
2. Names can be the same but the namespaces are ordered and the first 
namespace which contains the name is the one which is used.

I did look up to see if there was some computer-sciencey set of theories 
about namespace manipulation and didn't find any, but such operations 
are used repeatedly so this can be nothing new.

Maybe allowing those two ways would resolve the issue you mention.

-- 
James Harris

Thread

Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-01 14:40 +0000
  Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-01 14:55 +0000
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-02 21:05 +0000
      Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-03 01:18 +0000
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 01:03 +0000
      Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-06 06:40 -0500
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-06 21:10 +0000
          Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-07 06:58 -0500
            Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 01:23 +0000
              Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-09 02:28 -0500
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-09 02:44 -0500
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 23:26 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-11 07:44 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-12 21:59 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-14 01:45 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-14 10:59 +0000
      Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-06 06:40 -0500
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-06 21:20 +0000
          Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-07 06:58 -0500
            Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 10:30 +0000
  Re: Compiling and linking code from different places in the file system "James R. Kuyper" <jameskuyper@verizon.net> - 2018-03-01 11:11 -0500
    Re: Compiling and linking code from different places in the file system "James R. Kuyper" <jameskuyper@verizon.net> - 2018-03-01 13:51 -0500
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-03 09:48 +0000
  Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-03 12:25 +0000
    Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-03 15:32 +0000
      Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-04 07:52 +0000
      Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-04 08:43 +0000
        Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-05 07:58 +0000
          Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-06 21:37 +0000
            Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-07 21:02 +0000
        Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-05 15:29 +0000
          Re: Compiling and linking code from different places in the file system rugxulo@gmail.com - 2018-03-06 18:23 -0800
          Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-07 04:54 +0000
            Re: Compiling and linking code from different places in the file system Robert Wessel <robertwessel2@yahoo.com> - 2018-03-07 00:33 -0600
              Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-07 09:55 +0000
              Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-07 17:29 +0000
  Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-06 06:39 -0500
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-07 10:44 +0000
      Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-07 06:57 -0500
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 10:28 +0000
          Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-11 07:44 -0400
            Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-12 22:44 +0000
              Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-14 01:47 -0400
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-14 10:23 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 11:30 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-14 11:30 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 13:30 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-14 14:32 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 16:01 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-14 19:28 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-15 08:59 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-15 19:21 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-16 08:08 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-16 11:12 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-16 16:45 +0100
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-16 16:09 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-16 18:42 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-17 18:32 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-17 21:37 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-17 21:00 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-18 11:39 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-18 12:29 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-19 13:38 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-20 05:40 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-20 11:05 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-21 06:03 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-21 18:51 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-21 19:55 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-23 18:03 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-23 20:13 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-24 01:30 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-24 16:48 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-26 19:42 +0100
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-26 22:35 +0100
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-24 12:01 +0100
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-23 20:58 +0100
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-23 20:49 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-20 18:37 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-21 19:33 +0000
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-21 20:35 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-23 21:10 +0100
                Re: Compiling and linking code from different places in the file system Marco van de Voort <marcov@toad.stack.nl> - 2018-04-19 06:47 +0000
                Re: Compiling and linking code from different places in the file system Andy Walker <anw@cuboid.co.uk> - 2018-03-27 00:58 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-30 19:55 +0100
                Re: Compiling and linking code from different places in the file system Marco van de Voort <marcov@toad.stack.nl> - 2018-04-19 06:49 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-23 21:04 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-23 21:54 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-24 11:22 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-24 12:12 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-24 13:15 +0100
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-24 13:36 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-24 14:52 +0000
                Re: Compiling and linking code from different places in the file system Marco van de Voort <marcov@toad.stack.nl> - 2018-04-19 11:06 +0000
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-14 16:52 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-14 19:38 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-15 09:00 +0100
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-15 12:54 +0000
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-14 11:18 +0000
                Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 13:52 +0100
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-15 06:29 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-15 20:37 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-17 11:51 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-20 06:31 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-20 17:14 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-21 07:10 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-24 01:38 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-24 16:10 +0000
                Re: Compiling and linking code from different places in the file system Rod Pemberton <NoEmail@trraxvfeqa.prg> - 2018-03-24 20:05 -0400
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-25 16:55 +0100
  Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 13:39 +0100

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