create_header

Generates a header file consisting of the various macro definitions generated by other methods such as have_func and have_header. These are then wrapped in a custom #ifndef based on the header file name, which defaults to ‘extconf.h’.

For example:

# extconf.rb
require 'mkmf'
have_func('realpath')
have_header('sys/utime.h')
create_header
create_makefile('foo')

The above script would generate the following extconf.h file:

#ifndef EXTCONF_H
#define EXTCONF_H
#define HAVE_REALPATH 1
#define HAVE_SYS_UTIME_H 1
#endif

Given that the create_header method generates a file based on definitions set earlier in your extconf.rb file, you will probably want to make this one of the last methods you call in your script.