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From: Meredith Montgomery <mmontgomery@levado.to>
Newsgroups: comp.lang.php
Subject: Re: php 7.4: null["key"]
Date: Tue, 31 May 2022 19:27:22 -0300
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"J.O. Aho" <user@example.net> writes:

> On 30/05/2022 04.13, Meredith Montgomery wrote:
>> Meredith Montgomery <mmontgomery@levado.to> writes:
>> 
>>> I'm upgrading code to PHP 7.4, which will now blow a notice for things
>>> such as
>>>
>>>    null["key"]
>>>    (1.2)["key"]
>>>    (123)["key"]
>>>
>>> All of these seem to reduce to null.  (The footnote explains why I think
>>> so.)
>>>
>>> I have a lot of code which could be depending on such things.  I'd like
>>> to rewrite such code, but I have no idea how to find such code.  I
>>> suppose a loop such as
>>>
>>>    while ($a["key"]) { ... }
>
> foreach
> for
> do ... while
>
> finding all those cases you can use grep (generates a lot of false
> positives too):
> egrep "(while|for)" -r /path/to/your/scripts

Yes. 

I have millions of lines of code, so I think the best approach is indeed
to just go into production with PHP 7.4 and monitor the logs so that we
catch the deprecation warnings there --- and then we act.  I don't have
an army of programmers to analyze each possible loop.  I need to be
practical here.

> This will not take care of cases where someone has assumed they get an
> array and then they just need to get something from the array, for
> example:
>
> $var = function_returning_array();
> echo $var[0];

Indeed.

[...]

>>> How would you search for something like that?  I just have no idea.  My
>>> best idea is to just watch a log of errors and notices and try to spot
>>> the code that way.
>
> There ain't a good way to really find that, unitests had been useful,
> just run those and see which ones fail, and then fix the functions
> tested.

That's what I feared, but that's life.

>> I guess nobody had much to say here.  I'm tackling easier problems at
>> first, but I will eventually have to come back to this and make some
>> decision.  I suppose upgrading to PHP 7.4 and watching the a noisy log
>> with error_reporting = E_ALL (say) might give me more information.  But,
>> of course, I have no way of running every line of code, so there is
>> really no obvious strategy for something like that.
>
> You could take the time and write unitests now, it will make things
> easier next time. One such framework for php is https://phpunit.de
>
> As you will write tests for each function now, you will locate all the
> uses of arrays.

That's my next operation.  Start writing some important unit tests that
were never written.  Thank you so much for the phpunit.de
recommendation.  I checked and see that the project is using SimpleTest
instead.  I suppose anything reasonable is good enough for us.

Thank you for your attention.