How to use a variable in the expression of a 'normal' command?

Question

How can one use a variable when executing something via normal! in vimscript?

Example:

function! MyFunction(someArg)
   normal! (a:someArg)l
endfunction

This should move the cursor someArg steps to the right.

Answer 1

The execute function takes a string as argument, it expands the string and execute it a a regular ex command. Thus you can do:

function! MyFunction(someArg) 
    execute "normal! ". a:someArg. "l" 
endfunction

The . is a standard vimscript operator to concatenate strings.

execute can be shortened to exe.

See :h :execute

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EDIT I'll add a point about the comment of @Christian Brabandt about the concatenation with a ..

The doc says:

Multiple arguments are concatenated, with a space in between. To avoid the extra space use the "." operator to concatenate strings into one argument.

So the command could be:

execute "normal!" a:someArg . "l"

The executed command will be:

normal! 2l

Answer 2

For completeness's sake, I find the string concatenation using . is not pleasant to read. We may use printf to concatenate strings and variables for better readability.

execute printf("normal! %sl", a:someArg)

Answer 3

statox' answer is the best answer but I think the command looks cleaner that way:
(leave spaces between . and strings)

let i = 4
execute "normal! " . i . "l"