Groovy
Retrieve the first object (index [0]) among all objects attached to this page and of a certain class
obj = doc.getObject('XWiki.XWikiComments')
com.xpn.xwiki.api.Object@4b9e248b
Retrieve all objects attached to this page and of a certain class and one of their properties
objs = doc.getObjects('XWiki.XWikiComments')
[com.xpn.xwiki.api.Object@2851b578, com.xpn.xwiki.api.Object@c60edf6, com.xpn.xwiki.api.Object@2fa6b7d3, com.xpn.xwiki.api.Object@6a6e9615, com.xpn.xwiki.api.Object@23f734a, com.xpn.xwiki.api.Object@13aa006d, com.xpn.xwiki.api.Object@7e01fe30, com.xpn.xwiki.api.Object@34d741f1, com.xpn.xwiki.api.Object@202a5051]
objsAuthors = doc.getObjects('XWiki.XWikiComments').author
objsAuthor = doc.getObjects('XWiki.XWikiComments')[2].author
println objs[0].author
println objsAuthors
println objsAuthor