postlink(1) UNIX System V (Jul 18, 1997) postlink(1)
NAME
postlink - Portable Object Compiler Postlink Tool
SYNOPSIS
postlink [ options ] [ - ] [ linkmap [ outfile ] ]
DESCRIPTION
postlink is a tool that takes a link map as input and that
writes a C program to the stdout or to outfile. The program
essentially consists of a table of all Objective-C classes
that are linked into the program (as indicated by the link
map). The name stems from the fact that the C program is
then compiled by the objc driver and linked into the program
after a first link. The objcrt runtime can use this table
for initializing all classes.
AUTOMATIC INITIALIZATION
Most UNIX objc drivers are by default configured for
automatic initialization, and do NOT use this tool.
Automatic initialization determines at run-time what classes
are linked into the program, and does not need a compile-
time generated table of classes or a double link. It is
still possible to suppress automatic initialization by using
the -postlink option. Conversely, some non-UNIX drivers
that are configured with postlink by default, can be used
with the -noPostlink flag, but beware that, in general, the
reason to configure a driver with postlink is that the
automatic initialization code doesn't work for the
particular platform.
EXAMPLE
The command:
nm a.out | postlink > file.c
writes a C file to file.c that can be used by the objcrt
runtime for initialization. The table consists of BIND
functions that need to be called for all modules that were
compiled with the objc compiler. Note that this includes
all modules that need to be initialized, whether they define
a class, or just send an Objective-C message.
OPTIONS
-a file
Append file to the postlink output. This can be used
to prepare Objective-C packages that, when loaded with
dlopen(), automatically initialize themselves. Classes
defined in the package will automatically register
themselves to the runtime. The file that is appended
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postlink(1) UNIX System V (Jul 18, 1997) postlink(1)
to the postlink output, typically contains some C code
to process the postlink output (initializers,
finalizers).
-o file
Place output in file
-p symbol
Prepend symbol to the name _objcModules. This option
can be used when building tables of BIND functions for
shared objects that are going to be dynamically loaded
by a program (e.g. with dlopen()); in this case the
program needs more than just one _objcModules table.
-f format
Currently format can be one of unix, watcom msvc ibmvac
or metrowerks. The default format is unix. If the
format is unix, then the input is assumed to be the
output of the nm command (preferably the BSD nm
format). If the format is watcom, then the input is
assumed to be a WATCOM wlink link map, as generated
with option map=.
FILES
$OBJCDIR/lib/_prelink.o prelink stub file
SEE ALSO
objc(1), nm(1)
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