Vim Script: Loops, Iteration, and Exception Handling

{expr1} Short for `:else` `:if`, with the addition that there is no extra `:endif`. :wh[ile] {expr1} *:while* *:endwhile* *:wh* *:endw* *E170* *E585* *E588* *E733* :endw[hile] Repeat the commands between `:while` and `:endwhile`, as long as {expr1} evaluates to non-zero. When an error is detected from a command inside the loop, execution continues after the `endwhile`. Example: > :let lnum = 1 :while lnum <= line("$") :call FixLine(lnum) :let lnum = lnum + 1 :endwhile < NOTE: The `:append` and `:insert` commands don't work properly inside a `:while` and `:for` loop. :for {var} in {object} *:for* *E690* *E732* :endfo[r] *:endfo* *:endfor* Repeat the commands between `:for` and `:endfor` for each item in {object}. {object} can be a |List|, a |Blob| or a |String|. Variable {var} is set to the value of each item. When an error is detected for a command inside the loop, execution continues after the `endfor`. Changing {object} inside the loop affects what items are used. Make a copy if this is unwanted: > :for item in copy(mylist) < When {object} is a |List| and not making a copy, Vim stores a reference to the next item in the |List| before executing the commands with the current item. Thus the current item can be removed without effect. Removing any later item means it will not be found. Thus the following example works (an inefficient way to make a |List| empty): > for item in mylist call remove(mylist, 0) endfor < Note that reordering the |List| (e.g., with sort() or reverse()) may have unexpected effects. When {object} is a |Blob|, Vim always makes a copy to iterate over. Unlike with |List|, modifying the |Blob| does not affect the iteration. When {object} is a |String| each item is a string with one character, plus any combining characters. :for [{var1}, {var2}, ...] in {listlist} :endfo[r] Like `:for` above, but each item in {listlist} must be a list, of which each item is assigned to {var1}, {var2}, etc. Example: > :for [lnum, col] in [[1, 3], [2, 5], [3, 8]] :echo getline(lnum)[col] :endfor < *:continue* *:con* *E586* :con[tinue] When used inside a `:while` or `:for` loop, jumps back to the start of the loop. If it is used after a `:try` inside the loop but before the matching `:finally` (if present), the commands following the `:finally` up to the matching `:endtry` are executed first. This process applies to all nested `:try`s inside the loop. The outermost `:endtry` then jumps back to the start of the loop. *:break* *:brea* *E587* :brea[k] When used inside a `:while` or `:for` loop, skips to the command after the matching `:endwhile` or `:endfor`. If it is used after a `:try` inside the loop but before the matching `:finally` (if present), the commands following the `:finally` up to the matching `:endtry` are executed first. This process applies to all nested `:try`s inside the loop. The outermost `:endtry` then jumps to the command after the loop. :try *:try* *:endt* *:endtry* *E600* *E601* *E602* :endt[ry] Change the error handling for the commands between `:try` and `:endtry` including everything being executed across `:source` commands, function calls, or autocommand invocations. When an error or interrupt is detected and there is a `:finally` command following, execution continues after the `:finally`. Otherwise, or when the `:endtry` is reached thereafter, the next (dynamically) surrounding `:try` is checked for a corresponding `:finally` etc. Then the script processing is terminated. Whether a function definition has an "abort" argument does not matter. Example: > try | call Unknown() | finally | echomsg "cleanup" | endtry echomsg "not reached" < Moreover, an error or interrupt (dynamically) inside `:try` and `:endtry`

This section describes Vim script looping structures like ':while' and ':for', including their syntax, how they iterate over lists, blobs, and strings, and the implications of modifying the iterated object during the loop. It also covers ':continue' and ':break' for loop control. Additionally, the section explains error handling with ':try' and ':endtry', including the use of ':finally' for cleanup operations, and how these constructs interact with interrupts and errors within Vim scripts.