Cheers, mate!

That solves my issue (but with small fix).
do_unpack[postfuncs] += "do_latest_link"
instead
do_unpack[postfuncs] += "latest_link"

Because, without "do_" it says
WARNING: Function latest_link doesn't exist

Here is the whole bbclass:
DESCRIPTION = "Creates symlink to the latest version workdir of the package"

do_latest_link() {
    if [ -n "${WORKDIR}" ]; then
        linkname="$(dirname ${WORKDIR})/latest"
        rm -f $linkname
        ln -s $(basename ${WORKDIR}) $linkname
    fi
}
addtask latest_link after do_unpack

do_unpack[postfuncs] += "do_latest_link"

But for better understanding I made the more throughout look into the documentations. I found the information about "postfuncs" you talk about [1]. However, the tasks description [2] doesn't say anything about including the task in the process, it just describes the demanded order that the task is put ( addtask something after|before othertask ).

That is so, until I read "3.6. Variable Flags"  [3]. Where is quite clearly stated those variables control functionality and *dependencies*.
The documentation is quite unclear in that case.

[1] http://www.yoctoproject.org/docs/current/bitbake-user-manual/bitbake-user-manual.html#executing-tasks
[2] http://www.yoctoproject.org/docs/current/bitbake-user-manual/bitbake-user-manual.html#tasks
[3] http://www.yoctoproject.org/docs/current/bitbake-user-manual/bitbake-user-manual.html#variable-flags
Kind regards,
Bartosz Woronicz
Engineer, Software Configuration (SCM)
NSN - PL/Wroclaw
On 09.02.2016 10:10, EXT Burton, Ross wrote:

On 9 February 2016 at 08:37, Woronicz, Bartosz ( NSN - PL/Wroclaw) <bartosz.woronicz@nokia.com> wrote:
Ok, but I don't want to run it everytime, just after the do_unpack. What I need to put it in requirements for each recipe ?
Maybe something like

do_unpack[require] = "latest_link"

do_unpack[postfuncs] += "latest_link" will run latest_link after unpack has executed.

Ross