How to (1) get depth of execute-nesting and (2) interrupt the global command?

Question

From a sourced file I am running my vim script. The aim of the script is to run :global. I am searching for

\\%(pattern1.*/)\@<!pattern2

The patterns are variables, so I use execute; for the work to be done, I use a second nested level of execute.

It turns out that within the execute I must use |, not newlines, to separate commands.

execute ' g#' . WE_pattern1 .  ' ' . WE_patter2 . '#execute " try |  ...work | to | be | done... | catch ... | endtry | " '

1. How can I get the depth of execute-nesting?

2. How can I :finish the script under some condition? :finish always gives the error message E168: only in sourced ....

3. I catch CTRL-C interrupts, but after some processing how can I write that CTRL-C will be executed?

Answer 1

1. There's simply no need for the second execute (and so neither for nested double-quotes) here.

2. You can re-throw exception at any point (:h :throw). Of course, it'll become "user-defined", not "Vim:Interrupt". But that should not matter.