[RFC][VOTE] Rename T_PAAMAYIM_NEKUDOTAYIM to T_DOUBLE_COLON

4 years ago by G. P. B. — view source

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Hello internals,

As the two week discussion period has elapsed the vote is now open.

We did acknowledge the suggestion of dropping the token name from the error
message directly, but in our opinion this is an orthogonal change to the
one proposed, and has the risk of not landing in PHP 8.0.

The vote will close on the 9th of July.

https://wiki.php.net/rfc/rename-double-colon-token

Best regards

George P. Banyard

4 years ago by Andrea Faulds — view source

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Hi,

G. P. B. wrote:

https://wiki.php.net/rfc/rename-double-colon-token

I have voted No to this, and I hope I can convince some others to do the
same.

T_PAAMAYIM_NEKUDOTAYIM is such a famous token that there is probably
nobody in internals who doesn't know what it means, and for new
contributors, it is easy to find the definition, and note that it is
hardly the only token name that they will need to look up. It is also a
fun nod to the history of PHP, and I think it would be a shame to lose
that.

I mention the internals usage first and foremost, because it should be
remembered that token names are merely an implementation detail of the
PHP interpreter, unless you're using token_get_all (which by the way
already has the alias T_DOUBLE_COLON). In other words, it's not
something the vast majority of userland developers should ever encounter
or have to think about.

Of course, if T_PAAMAYIM_NEKUDOTAYIM was never encountered by userland
developers, this RFC wouldn't exist. The thing is, I don't think
T_DOUBLE_COLON should be encountered by userland developers either — in
my view, as an implementation detail, token names shouldn't be part of
parser error messages at all. If we were to remove token names from the
parser errors, we would avoid the problem this RFC seeks to solve. For
most tokens we could simply display the characters it corresponds to
(e.g. "::" for T_PAAMAYIM_NEKUDOTAYIM, which we already do!), and for
those with variable content (e.g. T_STRING) we could display a
human-readable description of what is expected (e.g. "an identifier").

I think the case for not renaming T_PAAMAYIM_NEKUDOTAYIM, and instead
improving the error messages, is stronger when you consider that is not
the only token with a name that might confuse people outside internals.
For example, T_STRING is a very common token, but the name is probably
going to surprise most userland developers who encounter it in an error
message, because it doesn't mean a literal string. Even for tokens with
more conventional names, it is unnecessary extra information. I think
renaming just T_PAAMAYIM_NEKUDOTAYIM is not a full solution to the
problem this RFC intends to solve.

Apropos of that:

We did acknowledge the suggestion of dropping the token name from the
error message directly, but in our opinion this is an orthogonal
change to the one proposed, and has the risk of not landing in PHP
8.0.

Is PHP 8.0 an all-important? If we don't rename the tokens, but simply
improve the error message, that might be allowable in a patch release
(e.g. 8.0.1).

(I also don't think we should rush things if we are unsure about them,
given the consequences that has had in the past.)

Thanks,
Andrea

4 years ago by Andrea Faulds — view source

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Hi again,

A further and perhaps more important thought: I think the token names
are actually the least confusing part of parser errors, even for the
famous T_PAAMAYIM_NEKUDOTAYIM. Changing it to T_DOUBLE_COLON may not
help much, because the parser only tells you what the next token it
expected was, not why it expected it, i.e. what is wrong with the
syntax. A user might think they need to add a :: but it's not their
actual problem.

For example, if you google for “T_PAAMAYIM_NEKUDOTAYIM” errors, one of
the classic examples where you got such an error was:

var_dump(empty(TRUE));

If the error had said T_DOUBLE_COLON it would still be mystifying: why
did PHP think you needed a :: there? And just adding one won't fix the
problem! The actual issue was that empty() used to not support arbitrary
expressions, only variables, and the expected T_PAAMAYIM_NEKUDOTAYIM is
because the only way TRUE could be part of a variable would be if it was
a class name (TRUE::$foo). The way to fix it is to replace empty() with
the ! operator, but you'd have a hard time figuring that out from the
error. I think this is the real reason T_PAAMAYIM_NEKUDOTAYIM was
famous: even if you knew it meant double colon, the error message is
still cryptic.

The good news is T_PAAMAYIM_NEKUDOTAYIM is no longer quite the menace it
once was. PHP 7's parser and syntax overhaul (thank you Nikita!) fixed
it in some places:

$ php -r 'var_dump(isset(TRUE));'
Fatal error: Cannot use isset() on the result of an expression (you
can use "null !== expression" instead)

And other places where you might have once seen T_PAAMAYIM_NEKUDOTAYIM
now give a different unhelpful parser error, which renaming
T_PAAMAYIM_NEKUDOTAYIM will not help with:

$ php -r 'unset(TRUE);'
Parse error: syntax error, unexpected ')', expecting '[' in Command
line code on line 1

So if there was ever a time to rename T_PAAMAYIM_NEKUDOTAYIM, it would
have been many years ago. There's much less benefit to renaming it now,
especially given it says “'::' (T_PAAMAYIM_NEKUDOTAYIM)” if you manage
to get an error containing it, so you don't even need to google it. The
specific name a token is given is the least of the problems there.

As for parser errors, I don't know how easy they would be to improve… is
it even possible for us to do so without using a hand-written parser
instead of an auto-generated one? (I have no idea.)

Regards,
Andrea

4 years ago by Kalle Sommer Nielsen — view source

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Hello Internals

The voting has closed with 44 for and 30 against. The RFC has not been
accepted as it did not meet the 2/3 requirement to be approved, thank
you to everyone for joining the discussions and turned out to vote.

--
regards,

Kalle Sommer Nielsen
kalle@php.net

4 years ago by Benjamin Eberlei — view source

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Hi,

G. P. B. wrote:

https://wiki.php.net/rfc/rename-double-colon-token

I have voted No to this, and I hope I can convince some others to do the
same.

T_PAAMAYIM_NEKUDOTAYIM is such a famous token that there is probably
nobody in internals who doesn't know what it means, and for new
contributors, it is easy to find the definition, and note that it is
hardly the only token name that they will need to look up. It is also a
fun nod to the history of PHP, and I think it would be a shame to lose
that.

I mention the internals usage first and foremost, because it should be
remembered that token names are merely an implementation detail of the
PHP interpreter, unless you're using token_get_all (which by the way
already has the alias T_DOUBLE_COLON). In other words, it's not
something the vast majority of userland developers should ever encounter
or have to think about.

Of course, if T_PAAMAYIM_NEKUDOTAYIM was never encountered by userland
developers, this RFC wouldn't exist. The thing is, I don't think
T_DOUBLE_COLON should be encountered by userland developers either — in
my view, as an implementation detail, token names shouldn't be part of
parser error messages at all. If we were to remove token names from the
parser errors, we would avoid the problem this RFC seeks to solve. For
most tokens we could simply display the characters it corresponds to
(e.g. "::" for T_PAAMAYIM_NEKUDOTAYIM, which we already do!), and for
those with variable content (e.g. T_STRING) we could display a
human-readable description of what is expected (e.g. "an identifier").

I think the case for not renaming T_PAAMAYIM_NEKUDOTAYIM, and instead
improving the error messages, is stronger when you consider that is not
the only token with a name that might confuse people outside internals.
For example, T_STRING is a very common token, but the name is probably
going to surprise most userland developers who encounter it in an error
message, because it doesn't mean a literal string. Even for tokens with
more conventional names, it is unnecessary extra information. I think
renaming just T_PAAMAYIM_NEKUDOTAYIM is not a full solution to the
problem this RFC intends to solve.

Apropos of that:

We did acknowledge the suggestion of dropping the token name from the
error message directly, but in our opinion this is an orthogonal
change to the one proposed, and has the risk of not landing in PHP
8.0.

Is PHP 8.0 an all-important? If we don't rename the tokens, but simply
improve the error message, that might be allowable in a patch release
(e.g. 8.0.1).

(I also don't think we should rush things if we are unsure about them,
given the consequences that has had in the past.)

This is the same reason that I voted no.

The token name has historic value and should be preserved as such
as several people suggested in the original RFC discussion, we should
just not display tokens in error messages anymore. That should have been
the RFCs solution, not renaming the token

Thanks,
Andrea

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4 years ago by Dan Ackroyd — view source

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The token name has historic value and should be preserved as such

I don't think it has historic value. It might have nostalgic value but
nostalgia for:

I think everyone hits it once or twice, has the "wtf?" moment, googles, and
never forgets it again - even if they can't pronounce it...

is not a great piece of nostalgia.

But regardless of the past value, it's the current and future
trade-offs we should be considering.

i.e. is the cost of changing it bigger or smaller than the benefit of
not having a token name that can only be reasoned about after
googling.

I haven't seen anyone say any cost for changing it. Even if the work
is done to improve the error messages, avoiding having a token that
you can't grok the meaning from the name of it, is a small
improvement.

So the tradeoff appears to be very small or zero cost, versus a
benefit for everyone who hasn't already stumbled into it as a blocker
for their understanding of internals.

cheers
Dan
Ack

4 years ago by Nikita Popov — view source

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Hi,

G. P. B. wrote:

https://wiki.php.net/rfc/rename-double-colon-token

I have voted No to this, and I hope I can convince some others to do the
same.

T_PAAMAYIM_NEKUDOTAYIM is such a famous token that there is probably
nobody in internals who doesn't know what it means, and for new
contributors, it is easy to find the definition, and note that it is
hardly the only token name that they will need to look up. It is also a
fun nod to the history of PHP, and I think it would be a shame to lose
that.

I mention the internals usage first and foremost, because it should be
remembered that token names are merely an implementation detail of the
PHP interpreter, unless you're using token_get_all (which by the way
already has the alias T_DOUBLE_COLON). In other words, it's not
something the vast majority of userland developers should ever encounter
or have to think about.

Of course, if T_PAAMAYIM_NEKUDOTAYIM was never encountered by userland
developers, this RFC wouldn't exist. The thing is, I don't think
T_DOUBLE_COLON should be encountered by userland developers either — in
my view, as an implementation detail, token names shouldn't be part of
parser error messages at all. If we were to remove token names from the
parser errors, we would avoid the problem this RFC seeks to solve. For
most tokens we could simply display the characters it corresponds to
(e.g. "::" for T_PAAMAYIM_NEKUDOTAYIM, which we already do!), and for
those with variable content (e.g. T_STRING) we could display a
human-readable description of what is expected (e.g. "an identifier").

I think the case for not renaming T_PAAMAYIM_NEKUDOTAYIM, and instead
improving the error messages, is stronger when you consider that is not
the only token with a name that might confuse people outside internals.
For example, T_STRING is a very common token, but the name is probably
going to surprise most userland developers who encounter it in an error
message, because it doesn't mean a literal string. Even for tokens with
more conventional names, it is unnecessary extra information. I think
renaming just T_PAAMAYIM_NEKUDOTAYIM is not a full solution to the
problem this RFC intends to solve.

Apropos of that:

We did acknowledge the suggestion of dropping the token name from the
error message directly, but in our opinion this is an orthogonal
change to the one proposed, and has the risk of not landing in PHP
8.0.

Is PHP 8.0 an all-important? If we don't rename the tokens, but simply
improve the error message, that might be allowable in a patch release
(e.g. 8.0.1).

(I also don't think we should rush things if we are unsure about them,
given the consequences that has had in the past.)

Thanks,
Andrea

Hey Andrea,

You convinced me! To vote "yes" on this RFC :P

I initially thought that this proposal is simply redundant, because the
issue would be fully addressed by

a) not displaying token names in errors, which I expect to happen for PHP
8.0, and
b) renaming T_PAAMAYIM_NEKUDOTAYIM as far as internal usage is concerned,
which is an implementation detail on which internals@ input is not required,

but I now realize that there might be friction on point b) without this
RFC, so it is better to accept it.

Regards,
Nikita

4 years ago by Rowan Tommins — view source

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Of course, if T_PAAMAYIM_NEKUDOTAYIM was never encountered by userland
developers, this RFC wouldn't exist. The thing is, I don't think
T_DOUBLE_COLON should be encountered by userland developers either —
in my view, as an implementation detail, token names shouldn't be part
of parser error messages at all. If we were to remove token names from
the parser errors, we would avoid the problem this RFC seeks to solve.
For most tokens we could simply display the characters it corresponds
to (e.g. "::" for T_PAAMAYIM_NEKUDOTAYIM, which we already do!), and
for those with variable content (e.g. T_STRING) we could display a
human-readable description of what is expected (e.g. "an identifier").

Just to confirm, I am actively working on exactly this, and although
slightly delayed by an outbreak of sunny weather, fully expect to have a
patch (and, if deemed necessary, RFC) in plenty of time for 8.0.

I intend to post a new thread with examples of old and new messages once
I've finalised the details.

Regards,

--
Rowan Tommins (né Collins)
[IMSoP]

4 years ago by G. P. B. — view source

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Hello Andrea, Benjamin, and others,

Better error messages are obviously better than just replacing the name of
the token, however this argument is saying that because this isn't perfect
let's do nothing.

I wasn't aware that Rowan had made good progress on his patch, however, if
this patch needs an RFC, which it might not, there is still no guarantee on
having better error messages for PHP 8.0.

Now, this may just me, but I find the argument that "::" is present
relatively weak as when I scan a PHP parse error, the first thing I look
for is the token name as there are only 3 parse errors which have the added
information of what the token represents, namely T_SL, T_SR, and
T_PAAMAYIM_NEKUDOTAYIM. T_SL and T_SR also have this issue but I would
expect beginners to not hit this as often as I don't expect them to do
anything with bit shifts, and the only other way that they may encounter it
is by doing a bad git merge.

I find it highly frustrating, and borderline offensive, that we are being
asked to go from a simple, non BC breaking, easy to enact change, to a
semi-major overhaul of how error messages should look like. I personally
have no interest in learning Bison and how to implement that as a separate
improvement to PHP. I'm just glad that Rowan decided to take on this
challenge.

Even if better error messages come about, some people will still need to
deal with the token, such as static analyser, code sniffers, code style
tools, etc. Obviously people working on these tools aren't beginners and
deal with the weird token name just fine, or use the T_DOUBLE_COLON alias
if they can. But why should it still be like this? This change has no BC
break, makes English the consistent language for token names. Moreover,
something being historic doesn't mean it shouldn't be touched.

My perception is that most of the community finds it baffling why anyone
would be against this change.

As for parser errors, I don't know how easy they would be to improve… is
it even possible for us to do so without using a hand-written parser
instead of an auto-generated one? (I have no idea.)

This may be done using Bison 3.6, which got released in May of this year,
as seen by this PR: https://github.com/php/php-src/pull/5416 However, I
don't expect us to be able to use this as Bison 3.6, won't be present on
most distrib until a couple of years.

Best regards
George P. Banyard

4 years ago by Stanislav Malyshev — view source

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Hi!

Better error messages are obviously better than just replacing the name of
the token, however this argument is saying that because this isn't perfect
let's do nothing.

I don't think this is the argument. I think the argument is rather than
half-fix the problem wrong way, let's fully fix it the right way.

I find it highly frustrating, and borderline offensive, that we are being
asked to go from a simple, non BC breaking, easy to enact change, to a
semi-major overhaul of how error messages should look like. I personally

I am not sure why is this "offensive" to you. Is there something in
overhauling error messages that goes against your principles or
religious beliefs? Sometimes overhauling is exactly what is the right
way to go, and not showing internal parser tokens seems to be quite
reasonable idea. If this idea is somehow "offensive" to you, I feel
sorry for you but it's not a reason to abandon this idea. It is also
quite a common things - many proposals in PHP have been rejected because
the community thought it's not the right way to approach things, I
myself have had some proposals rejected because of this. There's no
reason to feel offended by that.

My perception is that most of the community finds it baffling why anyone
would be against this change.

My perception is that most of the community couldn't care less for how
the tokens are named, and really shouldn't. It's an internal thing and
should stay this way. If they made to care, that's our fault and we
should fix it.

--
Stas Malyshev
smalyshev@gmail.com

4 years ago by Rowan Tommins — view source

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[...] there are only 3 parse errors which have the added
information of what the token represents, namely T_SL, T_SR, and
T_PAAMAYIM_NEKUDOTAYIM.

I'm not sure what you mean by there being only three. Since PHP 5.4, all
parser errors include the content of the token as well as its name, even
when this is basically repeating the same word, such as "unexpected
'echo' (T_ECHO)". There's even a bug in the implementation meaning that
casts repeat the name three times, e.g. "unexpected '(int)' (int)
(T_INT_CAST)".

This is why I was able to get a working prototype for new error messages
fairly quickly, and have had a draft PR open for nearly two weeks, but
also why I've spent a bit of time refining it to make sure edge cases
are handled better.

I find it highly frustrating, and borderline offensive, that we are being
asked to go from a simple, non BC breaking, easy to enact change, to a
semi-major overhaul of how error messages should look like.

I understand the general sentiment, that there were a lot of people in
the previous thread saying re-wording was a good idea, and not many
offering to work on it. I also appreciate that I hadn't provided any
public updates on my progress, and what hurdles needed to be over-come.
But you did know I was working on a patch, so the simple solution would
have been to ask me before opening the vote.

Regards,

--
Rowan Tommins (né Collins)
[IMSoP]

4 years ago by Claude Pache — view source

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Le 28 juin 2020 à 00:53, G. P. B. george.banyard@gmail.com a écrit :

My perception is that most of the community finds it baffling why anyone
would be against this change.

What baffles me, is the amount of discussion around changing the name of ONE token, whereas it is clear that a bunch of tokens (a few of them explicitly mentioned during the discussion phase of the RFC) have incomprehensible names, or worse, misleading names (T_STRING instead of T_IDENTIFIER), several of them appearing more often in error messages than T_DOUBLE_COLON (so, to be super-clear, I’m not talking about T_SL). And at this point I have still restricted my view to the issue of token name, whereas there is an obvious way to do better at relatively low cost, namely replacing the token name with a user-friendly description of the token.

I really appreciate the efforts made to make PHP better; thanks for that. But I friendly suggest that, each time you are going to propose an improvement, you take first a step back and consider how your change fits in its wider context.

—Claude