Redirect echom output in a function to a log file

Question

I would like to debug functions a bit more easily. Instead of running them and having to do:

:10 messages

To actually just have a vim.log file opened and tail -f'ed so I can see the output while it's running, without having to keep going into and out of messages and such.

Is there a way to do this? For example, in the following function:

func Toggle2 ()
    echom 'start toggle2...'
    echom 'end toggle2...'
endfunc

I would essentially like to do:

• Output goes to vim.log for this function
• But I don't want all the other vim-related messages. Just this function.

How could this be done? I tried doing the following:

func Toggle2 ()
    call execute('redir > vim.log')
    echom 'start toggle2...'
    echom 'end toggle2...'
    call execute('redir END')
endfunc

But received the following error:

E930: Cannot use :redir inside execute()

Answer 1

As matt points our, just redir:

redir > file
"...
redir END

Answer 2

The other possibility is to use a logging framework like mine.

When working on complex plugins for years it's really game changing. The main feature being:

• having the logs sent to the quickfix window with the file+line where the log has been done
• the possibility to choose which module is logging and which isn't (actually this is a consequence of how I use my logging framework) -- it works best, and very well, with autoload plugins that you haven't seen yet.

However, for your first plugins it may be a little overkill.

---

PS: I see :redir as the old solution which has few annoying drawbacks. I use it for portability issues when execute() isn't available. I even prefer call writefile('filename', execute('message')) -- I may have mixed-up the order of writefile() parameters.

PPS: I really feel like writing the same things over and over again. You really should avoid asking precisions on a topic in multiple questions