Using substitute on a variable

Question

How would I go about completing the following function in vimscript?

fun! Foo()     let l:bar = "Hello there, world!"     # Perform a substitution on l:bar, changing "world" to "kitten" endfun 

That is, how do I perform a substitution on a variable, rather than the current buffer.

I know that in order to substitute on the buffer, I can write

silent :%s/world/kitten/g 

but what is the equivalent command for substituting on a variable?

Answer 1

See :help substitute of :help substitute().

It is the counterpart of the substitute command (See :help :substitute).

substitute({expr}, {pat}, {sub}, {flags})       *substitute()*      The result is a String, which is a copy of {expr}, in which     the first match of {pat} is replaced with {sub}.  This works     like the ":substitute" command (without any flags).  But the     matching with {pat} is always done like the 'magic' option is     set and 'cpoptions' is empty (to make scripts portable).     'ignorecase' is still relevant.  'smartcase' is not used.     See |string-match| for how {pat} is used.     And a "~" in {sub} is not replaced with the previous {sub}.     Note that some codes in {sub} have a special meaning     |sub-replace-special|.  For example, to replace something with     "\n" (two characters), use "\\\\n" or '\\n'.     When {pat} does not match in {expr}, {expr} is returned     unmodified.     When {flags} is "g", all matches of {pat} in {expr} are     replaced.  Otherwise {flags} should be "".     Example: >         :let &path = substitute(&path, ",\\=[^,]*$", "", "")     This removes the last component of the 'path' option.          :echo substitute("testing", ".*", "\\U\\0", "")     results in "TESTING". 

In your example I guess that
let l:bar = substitute(l:bar, "world", "kitten", "") should work