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From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.lang.c++
Subject: Re: Borland Turbo C++ compile size
Keywords: topspeed linking
Message-ID: <2614@dataio.Data-IO.COM>
Date: 6 Aug 90 18:24:14 GMT
References: <7921@tekgvs.LABS.TEK.COM> <380@taumet.com> <1990Aug4.233013.20500@cs.columbia.edu>
Organization: Data I/O Corporation; Redmond, WA
Lines: 27

In article <1990Aug4.233013.20500@cs.columbia.edu> kearns@cs.columbia.edu (Steve Kearns) writes:
<The "problem" with "hello world" in C++ illustrates the need for
<smart linking, as provided by the Topspeed C compiler:  it only includes,
<in an executable, the functions and variables actually needed for the
<program being linked.  In contrast, all other linkers I know about today
<include every function and variable defined in a file, if just 1 function
<or variable is accessed.  
<Since C++ encourages the creation of large robust classes, one expects
<that a class implementation will contain a number of functions that
<are not actually used in an application.  Smart linking relieves the fear
<that using a large class for a simple purpose imposes a severe penalty on
<memory usage and program size.  
<How about it, compiler vendors?  Give us smart linking, please!

There is no difference between 'smart linking' and organizing the code
so that there is one function per OBJ file, and putting the OBJ files
into a library. Smart linking is simply a more convenient way to do it.

A standard linker could be used if the compiler emitted .LIB files
instead of .OBJ files (thus extending the OBJ file format is not
necessary).

I think you'll find this feature of limited value in C++ programs. The
reason is that virtual functions are *always* referenced (because of
their entry in the virtual function pointer table). Since most of the
complexity of classes is typically handled by virtual functions, they
all tend to get pulled in if any constructors are referenced.