Re: [PATCH 02/10] string-list.h: add string_list_pop function.

On Thu, Aug 9, 2018 at 2:56 PM Jeff King [off-list ref] wrote:

I think you could have helpers to spell the two lines above even more
nicely:

  while (list->nr) {
        work_on(list_top(list));
        list_pop(list); /* note this doesn't return anything! */
  }

But yes, it's not possible with the current functions.

I like this one most, and as we manage our own memory via the
alloc variable we also would not see a lot of memory churn for constant
push/pop traffic.

You can also use a list.h linked-list. Then removal from the list and
freeing are two separate operations (but it exercises your malloc a lot
more if you're constantly pushing and popping).

For that I'd have to define my own type derived from list.h to carry
the string and the util pointer, which looks very similar to the string_list
we already have from a users POV.

quoted

quoted

Where that falls down is if you really need work_on() to put more items
on the stack, but only after you've removed the current top. But then
writing it out may still be nicer, because it makes it clear you have to
do:

  const char *cur_string = xstrdup(list->items[list->nr-1].string);

Another way would be to use

  string_list_pop(&list, &string_dst, &util_dst);
i.e.
  /* Returns 0 if the dst was filled */
  int (struct string_list *, char **, void**)

as then we do not expose the internals and would not have issues
with reallocs.

Yes, I almost suggested that, but there's the question of memory
ownership of string_dst. Does it need freed or not? Is that answer
dependent on the strdup_strings flag?

Sure. But as the caller, you should know?
You constructed that string_list.