> From: Jeremy Curcio [mailto:j.cur...@icloud.com] > Sent: 26 June 2013 17:10 > To: Mike Willbanks > Cc: PHP Internals > Subject: Re: [PHP-DEV] Gauging Interest:RFC to add map() function > > > I am curious with something that is so easy; why would you want it in core? > > A lot of the Math Functions could be considered "so easy". > > ... > > floor() could be written out as: > ... [sort-of-floor implemented in PHP] ... > > The above examples are just a few that stick out to me I'm sure that looking > through the list of available math functions would provide a few more > examples. > Keeping these examples in mind, I don't follow the logic of range mapping > being > too easy to implement manually whenever it is needed to not warrant being > included in core.
Actually, that "floor" implementation will give incorrect answers in quite a few cases. "floor" is very difficult to implement correctly and efficiently for floating point numbers, which is why PHP offers a builtin function which delegates to the standard c lib's implementation of "floor". See https://github.com/php/php-src/blob/642721b38a9c5ebf336c81027c0dafd6f9246bd6/ext/standard/math.c#L320 That's the same for the other Math functions you have listed: there is real benefit to allowing access to the *correct* and efficient standard C implementations. This is not the case for the "map" function you have proposed: there is not a corresponding builtin function in the C standard library, which is why PHP doesn't offer it as a builtin. There is another serious problem with the proposal: the name "map" already has a specific meaning in programming languages: http://en.wikipedia.org/wiki/Map_(higher-order_function) http://php.net/manual/en/function.array-map.php For this proposal to have any traction, you need to: * demonstrate why PHP programmers need this implemented for them (e.g. for the "floor" func, it is easy to find tricky edge cases which justify the C lib's existence) * come up with a name which is self-explanatory and discoverable to users of PHP (i.e. if a PHP programmer needs to map floats from one range to another range in a linear fashion, what will they search for? "1-d affine transform PHP", perhaps?) TBH, I don't think this proposal has much chance of being accepted (I don't have voting rights BTW). Best, Rich Richard Bradley Tel : 020 7485 7500 ext 3230 | Fax : 020 7485 7575 softwire Sunday Times Best Small Companies - UK top 20 three years running Web : www.softwire.com | Addr : 325 Highgate Studios, 53-79 Highgate Road, London NW5 1TL Softwire Technology Limited. Registered in England no. 3824658. Registered Office : 13 Station Road, London N3 2SB -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
