How to create a post function that comments an issue with the transition that took place?

[Elizabeth Snitily]

We have a workflow where one status can transition to the other for multiple reasons, each with it's own associated transition/transition ID.

Is there a way to write a post function that will comment the name of the transition that took place, to prevent the user from having to access the history?

[Haddon Fisher]

I can't think of a way to do this using out-of-box functionality, but it would be a very simple Automation rule. 

[Marek Soukup]

You can use custom field instead of comment because there is a "update custom field" post-function. Or you can use commercial plug-in e.g. Jira Workflow Toolbox (https://apps.decadis.net/display/JWT/Post+Functions) which has "add comment" post-function.