Boost-Build :

hfp_at_[hidden]

---
Export/import symbols into/from a DLL without the need of a top-level 
header.
Such a typical header is now (logically) moved into the build system. 
Exporting becomes naturally a 'requirement' and importing will be 
an 'usage-requirement'.
In case of more than one component (dll) per main-projects with inter-
dependencies, that mean importing and exporting symbols for a single 
component at the same time, you can't have a simple control header 
that says 'dllexport' or(!) 'dllimport'. It's needed to tag each 
component with an own (unique) symbol. Now you have 
dllexport/dllimport per component (symbol).
This 'dll.lib' rule provides the standard to use the target name 
(uppercase) as symbol for the preprocessor and define it 
automatically with dllexport, dllimport or nothing (link static). The 
target name should always unique per component. Everything that needs 
to be exported/imported is named (tagged) naturally with the 
component name, i.e: class LIBMYCOMPONENT my_type { ... };
The 'dll.lib' rule use the original 'lib' rule and provides the same 
arguments and argument order. If you need a symbol name that isn't 
derived from the target name, you can use the optional 6'th argument 
to define an own symbol.
If you hold helper jamfiles in a local directory you only need one 
statement, i.e.:
import build/dll : lib ;
in your top-level jamfile ("the project") before any targed 
definition, where './build' contain this file ('dll.jam'). The 'lib' 
option after the colon prevents you from writing:
dll.lib ...
Now you can use an unqualified dll.lib (without dll):
lib ...
This is like a replacement of the built-in 'lib' rule.
---- jam code ---
rule lib ( names + : sources * : requirements * : default-build * : 
usage-requirements * : symbol ? )
{
echo $(names)": using extended version of 'lib' rule" ;
if ! $(symbol)
{
# By default use the uppercase name
symbol = $(names:U) ;
}
import os ;
if [ os.on-windows ]
{
requirements +=
<link>shared:<define>$(symbol)=__declspec(dllexport)
<link>static:<define>$(symbol)="" ;
usage-requirements +=
<link>shared:<define>$(symbol)=__declspec(dllimport)
<link>static:<define>$(symbol)="" ;
}
else {
requirements += <define>$(symbol)="" ;
usage-requirements += <define>$(symbol)="" ;
}
import builtin : lib : builtin.lib ;
builtin.lib $(names) : $(sources) : $(requirements) : $(default-
build) : $(usage-requirements) ;
}