X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=src%2Fgenerator.ml;h=97dc6ac4e43708cc053eb769e9bc271cdbd09aba;hp=743118be17733a1836f27dfb699dc9ae4e172c4e;hb=b8b0c99b46172712aa190f70182734934587af7b;hpb=8ff17e1c9cf348c93ac731281b1e4a0d5fa7caf3

diff --git a/src/generator.ml b/src/generator.ml
index 743118b..97dc6ac 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -9950,6 +9950,55 @@ the handle.
 
 =back
 
+=head1 AVAILABILITY
+
+From time to time we add new libguestfs APIs.  Also some libguestfs
+APIs won't be available in all builds of libguestfs (the Fedora
+build is full-featured, but other builds may disable features).
+How do you test whether the APIs that your Perl program needs are
+available in the version of C<Sys::Guestfs> that you are using?
+
+To test if a particular function is available in the C<Sys::Guestfs>
+class, use the ordinary Perl UNIVERSAL method C<can(METHOD)>
+(see L<perlobj(1)>).  For example:
+
+ use Sys::Guestfs;
+ if (defined (Sys::Guestfs->can (\"set_verbose\"))) {
+   print \"\\$h->set_verbose is available\\n\";
+ }
+
+To test if particular features are supported by the current
+build, use the L</available> method like the example below.  Note
+that the appliance must be launched first.
+
+ $h->available ( [\"augeas\"] );
+
+Since the L</available> method croaks if the feature is not supported,
+you might also want to wrap this in an eval and return a boolean.
+In fact this has already been done for you: use
+L<Sys::Guestfs::Lib(3)/feature_available>.
+
+For further discussion on this topic, refer to
+L<guestfs(3)/AVAILABILITY>.
+
+=head1 STORING DATA IN THE HANDLE
+
+The handle returned from L</new> is a hash reference.  The hash
+normally contains a single element:
+
+ {
+   _g => [private data used by libguestfs]
+ }
+
+Callers can add other elements to this hash to store data for their own
+purposes.  The data lasts for the lifetime of the handle.
+
+Any fields whose names begin with an underscore are reserved
+for private use by libguestfs.  We may add more in future.
+
+It is recommended that callers prefix the name of their field(s)
+with some unique string, to avoid conflicts with other users.
+
 =head1 COPYRIGHT
 
 Copyright (C) %s Red Hat Inc.