Re: Linking in C++

red floyd <>
Thu, 28 Apr 2011 10:48:14 -0700 (PDT)
On Apr 28, 7:01 am, gwowen <> wrote:

On Apr 28, 2:23 pm, d...@furrfu.invalid (Drew Lawson) wrote:

In article <c18b2cb6-1106-4dfc-86d1-2b803b060...@w24g2000yqb.googlegrou=>

        Ebenezer <> writes:

On Apr 27, 2:56 pm, jacob navia <> wrote:

Le 27/04/11 21:01, Pete Becker a crit :

On 2011-04-27 14:24:21 -0400, Ebenezer said:

On Apr 25, 4:53 pm, James Kanze <> wrote:

The granularity of most linkers is the object file. In general,
if you are writing a library, you put each non-virtual function
in a separate object file, and only those which are actually
called are included. (But this is, of course, a quality of
implementation issue for the library provider.)

This seems like a "premature optimization." I haven't come
across this much, but recall your mentioning it previously.

Not in a general-purpose library. If you get it wrong your custome=


complain about code bloat. As an extreme example, linking the enti=

re C

standard library into every application would not be a good thing.

For some people all optimizations are "premature" and they deliver
bloated, unoptimized programs. Code bloat slows down programs becaus=


it forces more main memory reads, and makes code cacheing less
efficient. It is a very important optimization.

I think this library -- is a
quality library, but there's no breaking things up
like that. I can't think of a library that splits
things up into such small chunks.

Taking a quick look at libc on my FreeBSD system, I see that it is
split into 849 files. I find this pretty common for general use
Less general libraries -- database APIs, toolsets, etc. -- probably
don't take that effort as often.


nm /usr/lib/libc.a | grep -F ".o:" | wc -l

on this Ubuntu Linux box suggests 1479 distinct ibject files in the
static library

nm /usr/lib/libc.a 2> /dev/null | grep " T " | wc -l

suggests 2377 defined global symbols, or about 1.5 exported symbols
per object file.

An easier way to do it:

On RHEL 5,

ar tv /usr/lib/libc.a | wc

shows 1391 object files

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