我如何在vimscript中完成以下函数？
fun! Foo()
let l:bar = "Hello there,world!"
# Perform a substitution on l:bar,changing "world" to "kitten"
endfun
也就是说，如何对变量执行替换，而不是当前缓冲区。
我知道，为了替换缓冲区，我可以写
silent :%s/world/kitten/g
但是什么是等价的命令替换变量？
请参阅：help substitute of：help substitute()。
它是替代命令的对应物(参见：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".
在你的例子我猜让l：bar = substitute(l：bar，“world”，“kitten”，“”)应该工作
