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Date: Tue, 2 Jul 2013 09:21:59 +0200
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To: Derick Rethans <derick@php.net>
Cc: PHP Internals List <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] Adding a time interval to an interval
From: simonsimcity@gmail.com (Simon Schick)

On Fri, Jun 28, 2013 at 11:20 PM, Derick Rethans <derick@php.net> wrote:
>
> Hey Simon,
>
> PS, please don't top-reply as per mailinglist guidelines:
> http://us2.php.net/reST/README.MAILINGLIST_RULES
>
> On Fri, 28 Jun 2013, Simon Schick wrote:
> > On Fri, Jun 28, 2013 at 7:10 PM, Derick Rethans <derick@php.net> wrote:
> >
> > > On Fri, 28 Jun 2013, Simon Schick wrote:
> > >
> > > > I'd like to extend the API of php by a method.
> > >
> > > Great, let me know if you need any help with the implementation, or
> > > when you have any questions on how it currently works.
> >
> > Sorry - I that was easy to missunderstand ;) I thought of providing
> > the idea. But I would happily also try to implement it by my own -
> > just to also have contributed to the php-core. If you could give me a
> > hint where to start - I feel quite lost in the code right now ... even
> > so I read the great tutorials about php-internals provided by Anthony
> > Ferrara.
> >
> > And this may take some time! I've just started with C/C++.
> >
> > Do you think this is an easy task to start? Depending on knowledge of
> > php-internals ;)
>
> It's not that difficult, but not the easiest thing either. Basically,
> you have to do the following steps:
>
> 1. in ext/date/lib/interval.c add a function that has two arguments of
>    the timelib_rel_time* type. It should return a *new*
>    timelib_rel_time* structure that has the two intervals added up
>    together. It shouldn't change either of the original
>    timelib_rel_time* arguments. Add the function definition to
>    ext/date/lib/timelib.h too.
> 2. You can only add two timelib_rel_time* arguments if neither of
>    first_last_day_of, special, have_weekday_relative, and
>    have_special_relative are set. You can'd add a "first day of next
>    month" to a "+5 days" interval - it only works for simple y:m:d h:i:s
>    intervals.
> 3. In ext/date/php_date.c add:
>
>    a. a new ARG_INFO struct after the one for
>       arginfo_date_interval_construct,
>    b. Add a new method, "add" after
>       PHP_ME_MAPPING(createFromDateString, date_interval_create_from_date_string,...
>    c. Add a new PHP_FUNCTION(date_interval_add) after the function
>       PHP_FUNCTION(date_interval_format) that takes two DateInterval
>       objects, extract the timelib_rel_time information, call the new
>       function that you've added in step 1, and replace the
>       timelib_rel_time* that is part of the DateInterval object with the
>       returned value.
>    d. Add a forwards declaration to php_date.h after
>       PHP_FUNCTION(date_interval_create_from_date_string);
>
> 4. Make sure that the function can be called both as a procedural way
>    (date_interval_add) and an object oriented way (DateInterval->add()).
>
> 5. Write test cases and put them in ext/date/tests.
>
> That's what I can think off right now.
>
> 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

Hi, Derick

I thought a bit about the changes here and came up with the following feedback:

If I can't add intervals where either one is relative, I'd also add a
method isRelative() to the class, where the user can check if it's a
relative interval.
But anyways - what happens if the interval is relative and you try to
access one of the public properties? They're all designed for static
intervals (let's say +5days), right?

What, if the user tries to add a relative to a fixed interval? Should
I trigger a E_WARNING, because it's no breaking error, but the value
can't be calculated?


Bye,
Simon