Understanding Vimscripts Through an Easy Example

Question

I want to write a function which takes two strings this and that as its arguments and replaces all instances of this with that.

So the function should look like:

function! ReplaceThisWithThat(this, that)
       "Main Stuff
.
.
.
endfunction

Can somebody please help?

Answer 1

You can do it very simply with:

function! ReplaceThisWithThat(this, that)
    execute "%s/" . a:this . "/" . a:that . "/g"
endfunction

Which will substitute every occurrence of a:this with a:that in the whole buffer.

If you want to perform that substitution on the content of some variable or register, you can use substitute() in your function:

function! ReplaceThisWithThat(something, this, that)
    return substitute(a:something, a:this, a:that, "g")
endfunction

which doesn't make much sense.

That said, everything you need to know is in :help eval.txt.

Answer 2

Function arguments have a: prefix.

function! ReplaceThisWithThat(this, that)
       "Main Stuff
 echo a:this "named argument 'this'
 echo a:that

 echo a:0 " postioned first argument
endfunction