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Date: Tue, 1 Aug 2017 09:35:38 +0200
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To: =?UTF-8?Q?Micha=C5=82_Brzuchalski?= <michal@brzuchalski.com>
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Subject: Re: [PHP-DEV] New functions: string_starts_with(), string_ends_with()
From: andreas@dqxtech.net (Andreas Hennings)

Thanks!
I did not find those, maybe the emails need to be enriched with keywords.
Like SEO-aware email authoring.

Ok. I am looking at the RFC and the old discussions at
https://marc.info/?l=3Dphp-internals&m=3D147017797404339&w=3D2

I don't know how to follow up on old threads that I don't have in my
email inbox.


So here is my feedback.

The RFC seems mostly fine as it is.
It does not contain anything like the string_clip_suffix() /
string_clip_prefix(), but I think these should be discussed
separately.

About the naming:
The "i" in str_ibegin and str_iend() seems ok to me.
I also strongly support separate functions instead of a parameter for
case sensitivity.

I also support the underscore. str_begin() is better than strbegin().


------------------------

Whether to have an "s" at the end:

https://marc.info/?l=3Dphp-internals&m=3D147017797404339&w=3D2
(Yasuo Ohgaki)

> It might be okay  to have "s" in function names, but if we want to be
> consistent,
> str_replace -> str_replaces
> str_ireplace -> str_ireplaces

I disagree with this analogy.

The "s" in str_begins() would be for "haystack beginS with needle".
An "s" in str_replaces() would stand for what?
Both "begin" and "replace" are verbs, but they have a different role
in the function name.
"begin" describes a state or condition we want to verfiy, whereas
"replace" is a command we give to the machine.

So to me it would make sense to have str_begins() and str_ends()
instead of str_begin() and str_end().

To me, str_end() means either "End the string!" (command) or "Give me
the end of the string!" (noun).

In fact Rowan Collins made the same argument here,
https://marc.info/?l=3Dphp-internals&m=3D147017844704431&w=3D2

> I think those names mean something different: "str_begin" sounds like an
> imperative "make this string begin with X"; "str_begins" is more of an
> assertion "the string begins with X". Ruby would spell it with a ? at
> the end. It's also the same form, grammatically, as the common "isFoo".
>
> Note that this logic holds for "str_replace", which *is* an imperative -
> you are not saying "tell me if X replaces Y", you are saying "please
> replace X with Y".

But then Will talks about consistency again.
https://marc.info/?l=3Dphp-internals&m=3D147018700406320&w=3D2

> I think like
> having an "s" at the end of the function names reads better, but
> omitting the "s" fits better with the existing function names and does
> not read bad. Therefore, I am in favor of dropping the "s".

Honestly, looking at the existing string functions at
http://php.net/manual/en/ref.strings.php
I don't see a lot of consistency here. Just a long list of garbled
abbreviations.

I also don't see any existing function where the verb has a similar
role as the "begin" in str_begin().
For all the existing string functions, the verb is a command.

I think a better comparison would be
file_exists()
function_exists()
class_exists()
is_subclass_of()
extension_loaded()
ncurses_has_colors()
ncurses_can_change_color()

What these functions have in common:
- The return value is boolean.
- The verb is not a command, but it describes a state or condition.

The verb is not always at the end of the function name, and it does
not always end with -s.
But the form and ending of the verb follows its grammatical role in
the sentence.

I think this is a much better guideline than following a wrong idea of
consistency.

-------------------------

Finally, I don't know why everything needs to be abbreviated.
Having str_* instead of string_* seems ok to me, and is consistent
with existing string functions.
But my first idea would have been more complete phrases like
str_ends_with, str_has_ending(), str_has_suffix(). Instead of just
str_end(), or str_ends().

On the other hand, shorter function names have their benefits. So.. no
strong opinion here.

--------------


-- Andreas






On Tue, Aug 1, 2017 at 8:29 AM, Micha=C5=82 Brzuchalski
<michal@brzuchalski.com> wrote:
> Hi Andreas,
>
> 2017-08-01 6:57 GMT+02:00 Andreas Hennings <andreas@dqxtech.net>:
>>
>> Hello list,
>> a quite common use case is that one needs to find out if a string
>> $haystack begins or ends with another string $needle.
>> Or in other words, if $needle is a prefix or a suffix of $haystack.
>>
>> One prominent example would be in PSR-4 or PSR-0 class loaders.
>> Maybe the use case also occurs when writing parsers..
>> In each of these two examples (parsers, class loaders), we care about
>> performance.
>>
>> (forgive me if this was discussed before, I did not find it anywhere
>> in the archives)
>>
>> --------------------------
>>
>> Existing solutions to this problem feel non-trivial, and/or are
>> suboptimal in performance.
>>
>> https://stackoverflow.com/questions/2790899/how-to-check-if-a-string-sta=
rts-with-a-specified-string
>>
>> https://stackoverflow.com/questions/834303/startswith-and-endswith-funct=
ions-in-php
>> This answer compares different solutions,
>> https://stackoverflow.com/a/7168986/246724
>>
>> Existing solutions:
>> (Let's focus on string_starts_with(), the other case is mostly
>> equivalent / symmetric)
>>
>> if (0 =3D=3D=3D strpos($haystack, $needle)) {..}
>> I have often seen this presented as the preferable solution.
>> Unfortunately, this searches the entire string, not just the
>> beginning. Especially if $haystack is really long, this can be a
>> waste.
>> E.g. if (0 =3D=3D=3D strpos(file_get_contents('some_source_file.php'),
>> '<?php')) {..} will search the entire file for an occurence of
>> '<?php'.
>>
>> if ($needle =3D=3D=3D substr($haystack, 0, strlen($needle))) {..}
>> This reserves new memory for the substring, which later needs to be
>> garbage-collected.
>> Also, this requires an additional function call to strlen() - which
>> adds even more clutter if $needle is an expression, not just a
>> variable.
>>
>> if (0 =3D=3D=3D strncmp($haystack, $needle, strlen($needle))) {..}
>> Needs the additional call to strlen().
>> Otherwise, this seems like a really good solution.
>>
>> if ('' =3D=3D=3D $needle || false !=3D=3D strrpos($haystack, $needle,
>> -strlen($haystack))) {..}
>> This is the funky solution from
>> https://stackoverflow.com/a/10473026/246724
>> The author says that it will be outperformed by strncmp() - so..
>>
>> if (preg_match('/^' . preg_quote($needle, '/') . '/', $haystack)) {..}
>> Clearly gonna be slower than other options.
>>
>> As said, all these solutions do work, but they are either suboptimal,
>> or they add clutter and overhead, or feel a bit like mind acrobatics.
>>
>> -----------------
>>
>> So, I wonder if it would be worthwhile to add new functions
>> string_starts_with() / string_has_prefix(), and string_ends_with() /
>> string_has_suffix().
>>
>> (Or maybe change strncmp(), so that the 3rd parameter $len is
>> optional. If $len is NULL / not provided, it would use the length of
>> the second (or first?) string.
>> (idea was that second parameter =3D needle).)
>>
>> For me personally, I am sure that I would use a new
>> string_starts_with() a lot more often than a lot of the other existing
>> string functions.
>> I don't think it is an exotic or niche use case.
>>
>> --------------
>>
>> Spinning this further:
>> A lot of times if I want to check if $haystack begins with $needle, I
>> will then need the rest of the string after $needle.
>> So
>> if (string_starts_with($haystack, $needle)) {
>>     $suffix =3D substr($haystack, strlen($needle));
>> }
>> or
>> if (string_ends_with($filename, '.php')) {
>>     $basename =3D substr($filename, 0, -4);
>> }
>>
>> I wonder if this could be somehow combined.
>> E.g.
>> if (FALSE !=3D=3D $basename =3D string_clip_suffix($filename, '.php')) {
>>     // Do something with $basename.
>> }
>>
>> ------------------
>>
>> One flaw of these new functions would be that they are less versatile
>> than other string functions.
>> They solve this problem, and nothing else.
>> On the other hand, this is the point, to avoid unnecessary overhead.
>>
>> The other problem would be, of course, "feature creep" aka "we have so
>> many string functions already".
>> This is a matter of opinion.
>> I would imagine the "cost" of new native functions is:
>> - global namespace pollution
>> - increased mental load to learn and remember all of them
>> - higher memory footprint of php engine?
>> - more C code to maintain
>> - a new doc page.
>> Did I miss something?
>>
>> ------------------
>>
>> -- Andreas
>>
>> --
>> PHP Internals - PHP Runtime Development Mailing List
>> To unsubscribe, visit: http://www.php.net/unsub.php
>>
>
> This idea was discussed 11 months ago https://externals.io/message/94787
> There is also a proper RFC
> https://wiki.php.net/rfc/add_str_begin_and_end_functions
> You might wanna contact with Will to get feedback from the idea.
>
> --
> regards / pozdrawiam,
> --
> Micha=C5=82 Brzuchalski
> about.me/brzuchal
> brzuchalski.com