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SubjectRe: [PATCH v3] string.h: Add str_has_prefix() helper
On Sat, Dec 22, 2018 at 07:22:07AM -0500, Steven Rostedt wrote:
> On Sat, 22 Dec 2018 18:28:18 +0900
> Namhyung Kim <namhyung@kernel.org> wrote:
>
> > >
> > > for (i = 0; i < hist_data->attrs->n_actions; i++) {
> > > str = hist_data->attrs->action_str[i];
> > >
> > > - if (str_has_prefix(str, "onmatch(")) {
> > > - char *action_str = str + sizeof("onmatch(") - 1;
> > > + if ((len = str_has_prefix(str, "onmatch("))) {
> > > + char *action_str = str + len;
> >
> > IMHO, returning (match) length might confuse people that it might
> > support partial match and returns the length actually matched rather
> > than full match. If I knew it always returns the length of prefix (or
> > 0) why it matters? Using strlen() in the next line will have same
> > effect of compiler optimization for the constant strings, no?
> >
> > if (str_has_prefix(str, "onmatch(")) {
> > char *action_str = str + strlen("onmatch(");
>
> The reason to return the length was to get rid of the need for
> duplicating the strlen("xxxx") because it's a burden to keep the two
> the same. Not only that, a lot of places just do "str + 7" because it's
> easier to type.
>
> Yes, it has the same effect on the compiler, but that's not what we are
> trying to solve. We are trying to get rid of the duplication, because
> that requires humans to get it right, and humans are not good at that.

Then I'm ok with that. :)

Thanks,
Namhyung

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