What is the vimscript's no operation statement?

Question

What is the NOP code for vimscript?

Answer 1

VimScript interpreter ignores colons and spaces, so : could be qualified as "nop" command. For example, echo 'foo' | : is the same as just echo 'foo'.

However, there's a problem: due to Vi compatibility :| is forcefully parsed as :print, so echo 'foo' | : | echo 'bar' surprisingly transforms into echo 'foo' | print | echo 'bar'.

To deal with this one can create a user-defined command, e.g.

command! -bar Nop :

Now this works: echo 'foo' | Nop | echo 'bar'

Answer 2

According to the url provided:

The simplest possible statement in C that behaves like a NOP is the so-called null statement, which is just a semi-colon in a context requiring a statement. (A compiler is not required to generate a NOP instruction in this case; typically, no instructions whatsoever would be generated.)

  ;

Alternatively, an empty block (compound statement) may be used, and may be more legible:

  {}

What about "empty command" :

func! Test()
    :
endfunc