# [RFC] Constant Scalar Expressions (with constants) - Thread: https://externals.io/message/70048 - Original archive: https://news-web.php.net/php.internals/70048 - Started by Bob Weinand on 2013-11-07T12:01:11+00:00 - Messages: 14 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #70048 — Bob Weinand — 2013-11-07T12:01:11+00:00 URL: https://externals.io/message/70048#70048 Hi! As you all know, Anthony Ferrara had withdrawn his RFC a few months ago, which was without support for constants in these expressions: const foo = 10; const bar = 10 * foo; The use of a constant in a declaration of a constant was not yet possible with his patch. That's what I changed. Enjoy reading the RFC at: https://wiki.php.net/rfc/const_scalar_exprs Bob Weinand Special thanks go to Dmitry who had helped me a lot with feedback and a deep review of the patch. --- ## #70049 — Lars Strojny — 2013-11-07T12:31:14+00:00 URL: https://externals.io/message/70048#70049 · In reply to: #70048 Hi Bob, thanks for your work, it’s awesome. One thing about constants: Take this example: const FOO = 2; class Klass { const FOO = 1; const BAR = FOO; } Here FOO is ambiguous, as it could resolve to 2 or to 1. If I understood it correctly, global constants are not yet implemented but I would suggest to always force prefixing the constant to get rid of the ambiguity and allow for future extension. const FOO = 2; class Klass { const FOO = 1; const BAR = self::FOO; } Does that make sense? cu, Lars > Hi! > > As you all know, Anthony Ferrara had withdrawn his RFC a few months ago, which was without support for constants in these expressions: > > const foo = 10; > const bar = 10 * foo; > > The use of a constant in a declaration of a constant was not yet possible with his patch. > > That's what I changed. > > Enjoy reading the RFC at: > > https://wiki.php.net/rfc/const_scalar_exprs > > Bob Weinand > > Special thanks go to Dmitry who had helped me a lot with feedback and a deep review of the patch. --- ## #70050 — Nikita Popov — 2013-11-07T12:41:55+00:00 URL: https://externals.io/message/70048#70050 · In reply to: #70049 > Hi Bob, > > thanks for your work, it’s awesome. One thing about constants: > > Take this example: > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = FOO; > } > > Here FOO is ambiguous, as it could resolve to 2 or to 1. If I understood > it correctly, global constants are not yet implemented but I would suggest > to always force prefixing the constant to get rid of the ambiguity and > allow for future extension. > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = self::FOO; > } > > Does that make sense? > The code snippets you posted are *already* supported (e.g. in PHP 5.5). FOO will resolve to the globals constant, self::FOO to the class constant. Presumably the extended support in static expressions will retain those semantics :) Nikita --- ## #70051 — Sebastian Krebs — 2013-11-07T12:43:15+00:00 URL: https://externals.io/message/70048#70051 · In reply to: #70049 2013/11/7 Lars Strojny > Hi Bob, > > thanks for your work, it’s awesome. One thing about constants: > > Take this example: > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = FOO; > } > > Here FOO is ambiguous, as it could resolve to 2 or to 1. If I understood > it correctly, global constants are not yet implemented but I would suggest > to always force prefixing the constant to get rid of the ambiguity and > allow for future extension. > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = self::FOO; > } > > Does that make sense? > Yes, also from the consistency point of view: I'd expected to refer class constants via its class name (or self/static). Having to ways to refer them is confusing. > > cu, > Lars > > > > > […] > which was without support for constants in these expressions: > > […] > possible with his patch. > > […] > deep review of the patch. > > […] > > -- github.com/KingCrunch --- ## #70052 — Bob Weinand — 2013-11-07T12:45:25+00:00 URL: https://externals.io/message/70048#70052 · In reply to: #70049 Hi Lars, In what way is this ambiguous? I just tested; FOO never equals self::FOO. FOO always is a global constant, while self::FOO (and Klass::FOO) is the only way to refer to the class constant. const FOO = 2; class Klass { const FOO = 1; const BAR = FOO; // value two, global constant, and if FOO is not defined, Klass::Bar === "FOO". } Bob Am 7.11.2013 um 13:31 schrieb Lars Strojny : > Hi Bob, > > thanks for your work, it’s awesome. One thing about constants: > > Take this example: > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = FOO; > } > > Here FOO is ambiguous, as it could resolve to 2 or to 1. If I understood it correctly, global constants are not yet implemented but I would suggest to always force prefixing the constant to get rid of the ambiguity and allow for future extension. > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = self::FOO; > } > > Does that make sense? > > cu, > Lars > > > > > […] --- ## #70053 — Remi Collet — 2013-11-07T13:03:44+00:00 URL: https://externals.io/message/70048#70053 · In reply to: #70048 Le 07/11/2013 13:01, Bob Weinand a écrit : > Enjoy reading the RFC at: > > https://wiki.php.net/rfc/const_scalar_exprs I have enjoy it. Really nice. Remi. --- ## #70054 — Patrick Schaaf — 2013-11-07T13:08:52+00:00 URL: https://externals.io/message/70048#70054 · In reply to: #70048 Am 07.11.2013 13:01 schrieb "Bob Weinand" : > > https://wiki.php.net/rfc/const_scalar_exprs Wow, this looks really nice! Will this work with class autoloading, too? i.e. will class foo { const X = bar::X; } trigger autoloading for class bar? best regards Patrick --- ## #70055 — Lars Strojny — 2013-11-07T13:10:11+00:00 URL: https://externals.io/message/70048#70055 · In reply to: #70052 Hi Bob, alright, my fault not getting the ternary operator example :) Thanks for the clarification! Lars > Hi Lars, > > In what way is this ambiguous? > > I just tested; FOO never equals self::FOO. FOO always is a global constant, while self::FOO (and Klass::FOO) is the only way to refer to the class constant. > > const FOO = 2; > > class Klass > { > const FOO = 1; > const BAR = FOO; // value two, global constant, and if FOO is not defined, Klass::Bar === "FOO". > } > > Bob > > Am 7.11.2013 um 13:31 schrieb Lars Strojny : > > > […] --- ## #70056 — Nikita Popov — 2013-11-07T13:12:57+00:00 URL: https://externals.io/message/70048#70056 · In reply to: #70054 > Am 07.11.2013 13:01 schrieb "Bob Weinand" : > > […] > > Wow, this looks really nice! > > Will this work with class autoloading, too? i.e. will > > class foo { > const X = bar::X; > } > > trigger autoloading for class bar? > Once again, the code you posted is already supported, not really part of this proposal. And yes, it will invoke the autoloader, see http://codepad.viper-7.com/2Xz8ux :) Nikita --- ## #70057 — Van Peer Ilias — 2013-11-07T13:15:44+00:00 URL: https://externals.io/message/70048#70057 · In reply to: #70056 It's nice to see people get excited for things they already have. Should lead to a little more appreciation of what's already there, I guess.. -----Original Message----- From: Nikita Popov [mailto:nikita.ppv@gmail.com] Sent: donderdag 7 november 2013 14:13 To: Patrick Schaaf Cc: Bob Weinand; internals Subject: Re: [PHP-DEV] [RFC] Constant Scalar Expressions (with constants) > Am 07.11.2013 13:01 schrieb "Bob Weinand" : > > […] > > Wow, this looks really nice! > > Will this work with class autoloading, too? i.e. will > > class foo { > const X = bar::X; > } > > trigger autoloading for class bar? > Once again, the code you posted is already supported, not really part of this proposal. And yes, it will invoke the autoloader, see http://codepad.viper-7.com/2Xz8ux :) Nikita This e-mail and all files transmitted as attachment(s) thereto are confidential and solely intended for the individual to whom or the organization to which they are addressed. If you received this e-mail by mistake, please notify Cegeka's Service Desk at cegeka.support@cegeka.be or call +32 (0)11 240 363. We thank you in advance. Cegeka hereby confirms that this message has been swept by Sophos for the presence of viruses. --- ## #70058 — Patrick Schaaf — 2013-11-07T13:19:57+00:00 URL: https://externals.io/message/70048#70058 · In reply to: #70056 Am 07.11.2013 14:12 schrieb "Nikita Popov" : > > Once again, the code you posted is already supported, not really part of this proposal. Blush. I'm still sitting at 5.4.x :) > And yes, it will invoke the autoloader, see http://codepad.viper-7.com/2Xz8ux :) "Interesting" line number in that error message..... best regards Patrick --- ## #70059 — Bob Weinand — 2013-11-07T13:27:32+00:00 URL: https://externals.io/message/70048#70059 · In reply to: #70058 Am 7.11.2013 um 14:19 schrieb Patrick Schaaf : > Am 07.11.2013 14:12 schrieb "Nikita Popov" : > > […] > this proposal. > > Blush. I'm still sitting at 5.4.x :) That's no excuse :-P The only thing that RFC introduces are operations on constants and constant values on definitions of constants/properties/statics. Not more. > > […] > http://codepad.viper-7.com/2Xz8ux :) > > "Interesting" line number in that error message..... Yes, class constants are evaluated upon their first use. Bob > > best regards > Patrick --- ## #70061 — Derick Rethans — 2013-11-07T13:34:09+00:00 URL: https://externals.io/message/70048#70061 · In reply to: #70048 > Hi! > > As you all know, Anthony Ferrara had withdrawn his RFC a few months ago, which was without support for constants in these expressions: > > const foo = 10; > const bar = 10 * foo; > > The use of a constant in a declaration of a constant was not yet possible with his patch. > > That's what I changed. > > Enjoy reading the RFC at: > > https://wiki.php.net/rfc/const_scalar_exprs https://github.com/bwoebi/php-src/compare/const_scalar_exprs#diff-4d0b93094aafe8cf519b4f0a3322f471L590 -#define IS_CALLABLE 10 +#define IS_CONSTANT_AST 10 +#define IS_CALLABLE 11 Can I please suggest that you do not change existing constant values? You're using a macro to check for the constant type anyway, so you can do the complex checking for constant types in there. I'm also of the opinion that just " This can allow for writing far easier to understand code, by allowing for far more expressive code." is by far not enough of a justification for a syntax addition. Please please try to be convincing by having good arguments, presenting alternatives and cons. cheers, Derick -- http://derickrethans.nl | http://xdebug.org Like Xdebug? Consider a donation: http://xdebug.org/donate.php twitter: @derickr and @xdebug Posted with an email client that doesn't mangle email: alpine --- ## #70062 — Bob Weinand — 2013-11-07T16:02:21+00:00 URL: https://externals.io/message/70048#70062 · In reply to: #70061 Am 7.11.2013 um 14:34 schrieb Derick Rethans : > > > […] > > https://github.com/bwoebi/php-src/compare/const_scalar_exprs#diff-4d0b93094aafe8cf519b4f0a3322f471L590 > > -#define IS_CALLABLE 10 > +#define IS_CONSTANT_AST 10 > +#define IS_CALLABLE 11 > > Can I please suggest that you do not change existing constant values? > You're using a macro to check for the constant type anyway, so you can > do the complex checking for constant types in there. Just comparing twice (> and <) should be faster than comparing three times (three times an ==). Dmitry had suggested this to me. And I don't see the big disadvantage here as IS_CALLABLE is anyway just used for the typehint. Nothing there which relies on the fact that IS_CALLABLE equals to 10. > I'm also of the opinion that just " This can allow for writing far > easier to understand code, by allowing for far more expressive code." is > by far not enough of a justification for a syntax addition. Please > please try to be convincing by having good arguments, presenting > alternatives and cons. Well, that's _the_ justification. I can also list other justifications, but that'd be just other ways to express the same, so I just kept it simple. Alternatives… don't really exist. (at least not in function signatures for example) And cons? Can't think of any problem with it. Bob > cheers, > Derick > > -- > http://derickrethans.nl | http://xdebug.org > Like Xdebug? Consider a donation: http://xdebug.org/donate.php > twitter: @derickr and @xdebug > Posted with an email client that doesn't mangle email: alpine