Advice on the use of :exe "norm!" vs. built in functions when writing vimscipt and plugins

Question

I've been using vim for about 3 years and am starting to write my first plugin. I've noticed when looking at the code of other popular plugins that the functions very rarely seem to achieve their aim with lines like:

execute "normal! <some commands>"

Instead opting to use Vim's built in functions. Given the power of Vim's normal mode commands to do so much, what is the general reason for not employing them more often when writing plugins? For example is there a good reason to prefer code (A) or (B) (given that they achieve the same result):

Code (A):

let l = line(".")
let c = col(".")

call search('mysearch')
call setline(line("."), 'better')

call cursor(l, c)

Code (B):

normal! mx

execute "normal! /mysearch/\<CR>"
normal! 0c$better

normal! `x

Code (A) seems a little more readable, and won't clobber the marks (and not the search registers?). Is there a more important reason I'm missing?

Answer 1

In no particular order.

1. Readability Any sequence of normals, except a very short one, is nearly impossible to read and understand. Vimgolf can't lie.
2. Clobbering registers etc. Quite often there is more things to change than one can even remember of. For example, your code sets at least four(!) registers and six(!) marks. Plus :h changelist and :h jumplist. Sometimes it's good, but usually scripts need to preserve stuff.
3. Error handling Normals could fail in the middle of a sequence. Also, how do you know if "mysearch" was even found or not?
4. Behaviour change Many normals work differently depending on user-settable options such as &virtualedit, &selection, &whichwrap, &wrap, &iskeyword and so on. Again, sometimes it's good, but usually it's a pain.

Answer 2

Not an answer, but I think you'll appreciate it.

let saved_pos = getcurpos()
call search('mysearch')
normal! 0c$better
call setpos('.', saved_pos)

I used "better" functions ("better" - maybe not. Up to you). And mixed/matched normals with scripts. What do you think?

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Read this: Master Wq and the Markdown acolyte from https://blog.sanctum.geek.nz/vim-koans/ :)

Scripts beat normal commands in terms of composability. Scripts work with data instead of strings. It's like bash commands vs. powershell commands (if you have experience with that). Or it's like understanding and transforming MEANING vs. characters. That's more univeral, but unfortunately more abstract.

So... if you're building something small, normals are great! And if you're building something large, scripts are great!