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In-Reply-To: <CAFMT4NrCbWyy9ERTPpXv++XqQpGmMUL8j3T96pSDHugJJ+2WPA@mail.gmail.com>
Date: Mon, 11 Feb 2019 11:13:20 -0500
Message-ID: <CAPKYkKxNqHiJgNghsnCD29mzt22bYpx5_YaOwywji88jLaXQSw@mail.gmail.com>
To: Levi Morrison <levim@php.net>
Cc: "Woortmann, Enno" <enno.woortmann@web.de>, internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="0000000000000bb1580581a0971b"
Subject: Re: [PHP-DEV] Variadic is_*() functions
From: chasepeeler@gmail.com (Chase Peeler)

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On Mon, Feb 11, 2019 at 10:59 AM Levi Morrison <levim@php.net> wrote:

> On Mon, Feb 11, 2019 at 8:39 AM Woortmann, Enno <enno.woortmann@web.de>
> wrote:
> >
> > Hi internals,
> >
> > as I reviewed a bunch of code for handling data from different sources
> > (eg. json) in the last days I stumbled over code like this multiple
> times:
> >
> >
> > if (!(is_numeric($input['example1']) && is_numeric($input['example2'])))
> {
> >
> >
> > if (!is_numeric($input['example1'] || !is_numeric($input['example2'])) {
> >
> >
> > and I had multiple problems with this.
> >
> > * it's kinda hard to read
> >
> > * multiple writings for the same logic
> >
> > * ends up in complex conditionals
> >
> >
> > I searched for discussions regarding this topic and found it was
> > mentioned in a 'side thread' of the RFC for changing empty() to a
> > variadic a few years ago (https://externals.io/message/82549#82641) and
> > I'd like to collect some feedback if it's wothy to revisit the topic to
> > write the above example as:
> >
> >
> > if (!is_numeric($input['example1'], $input['example2'])) {
> >
> >
> > Except the is_callable() method all is_*() methods could be extended
> > with a variadic behaviour which would check the given values from the
> > left to the right and abort if a value doesn't match the condition (in
> > the example if a given value is not numeric). So all in all there are
> > some points to talk about: Revisit the discussion? Which functions are
> > reasonable to be extended? If all functions are reasonable: what to do
> > with is_callable()?
> >
> > regards,
> > Enno
> >
> > --
> > PHP Internals - PHP Runtime Development Mailing List
> > To unsubscribe, visit: http://www.php.net/unsub.php
>
> My position is the same: pushing the variadic behavior into the
> functions means that each function needs to pick `||` or `&&`
> behavior, both of which are useful. I would rather see more
> descriptive function names, such as `all_of` or `any_of`:
>
>     if (!all_of('is_numeric', [$input['example1'],
> $input['example2']])) {/*...*/}
>
> These do not need to be part of PHP core, but perhaps they could be.
>
> I recognize that there is one downside, which is that lazy evaluation
> is lost, but generally don't see it to be an issue in these specific
> cases.
>
> Lazy evaluation doesn't have to be lost if the all_of and any_of functions
are written correctly. all_of will return false as soon as one of them
fails, and any_of will return true as soon as one of them passes.
<?php

function all_of($callback,...$params){
   foreach($params as $param){
      if(!$callback($param)){
        return false;
      }
   }
   return true;
}

function any_of($callback,...$params){
   foreach($params as $param){
      if($callback($param)){
        return true;
      }
   }
   return false;
}

Unless you are talking about cases like this:
if(is_numeric(reallyFastFunc($foo)) || is_numeric(reallySlowFunc($bar)))
In that case, you might be able to short circuit the evaluation of
reallySlowFunc($bar), which wouldn't be the case with
if(any_of('is_numeric',reallyFastFunc($foo),reallySlowFunc($bar))){}

However, at that point, I'd say that
1.) If performance isn't an issue, break those function calls out and make
your code more readable:
$f1 = reallyFastFunc($foo);
$f2 = reallySlowFunc($bar);
if(any_of('is_numeric',$f1,$f2)){}
2.) If performance is an issue, fall back to the old method
if(is_numeric(reallyFastFunc($foo)) || is_numeric(reallySlowFunc($bar))){}


> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
> --
-- Chase
chasepeeler@gmail.com

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