On 31 Aug 2007, at 1:56 AM, David Lutterkort wrote:
On Thu, 2007-08-30 at 17:32 +0800, Meng Kuan wrote:
[root@dell1 libvirt_ruby]# irb irb(main):001:0> require 'libvirt_ruby' => true irb(main):002:0> conn = Libvirt_ruby.virConnectOpenReadOnly("") => #<SWIG::TYPE_p__virConnect:0x2aaaaabc46c8> irb(main):003:0> dom = Libvirt_ruby.virDomainLookupByID(conn, 0) => #<SWIG::TYPE_p__virDomain:0x2aaaaabb5df8> irb(main):004:0> ret = Libvirt_ruby.virDomainGetInfo(dom, info) NameError: undefined local variable or method `info' for main:Object from (irb):4 irb(main):005:0>
I am not sure how to create and pass in a ptr to a virDomainInfo struct object into the virDomainGetInfo call within ruby.
virDomainGetInfo uses the info structure to return the info. It's going to be hard to replicate that 1-1 in Ruby; but you'd get a much better, more Ruby-ish API if you structure the various libvirt calls into a number of classes (Libvirt::Connection, Libvirt::Domain, Libvirt::DomainInfo etc.) so that your above code would look something like
conn = Libvirt::connectReadOnly("") # Returns a Libvirt::Connection dom = conn.lookupDomainByID(0) # Returns a Libvirt::Domain info = dom.getInfo() # Returns a Libvirt::DomainInfo
What I was missing was the "-autorename" argument when calling swig, i.e. swig -ruby -autorename libvirt.i After compile and install of the resulting libvirt.so, here's what I can do in ruby: require 'libvirt' conn = Libvirt.vir_connect_open_read_only("") dom = Libvirt.vir_domain_lookup_by_id(conn, 0) info = Libvirt::VirDomainInfo.new Libvirt.vir_domain_get_info(dom, info) puts info.state # => 1 puts info.maxMem # => 1047552 It's far from ruby-ish, but it works.
I doubt that you can do that with Swig, but it's not terribly hard to write bindings by hand. Have a look at existing bindings, e.g. for rpm[1] or gamin[2].
I'll probably look into writing bindings by hand later on, but at this time due to my inexperience with C programming and lack of time, I am thinking of writing Ruby classes that wrap these C calls and use those Ruby classes instead. Thanks for the pointers, David. Much appreciated. cheers, mengkuan