Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.php > #10575

Re: switch with case 0

Show all headers | View raw

On 08/18/2013 09:22 AM, Thomas Mlynarczyk wrote:
> Norman Peelman schrieb:
>
>>   Why is it unreasonable? After all, FORM data is all strings to begin
>> with. PHP will type juggle "12345" to 12345 just fine. The whole idea
>> behind this after all is not about having strings like "2foo".
>
> GET/POST data arrive as strings, yes. So the first thing one does in a
> PHP script is to validate that data and convert it *explicitly* to the

   PHP started *before* the big validation era...

> correct type. One does not "leave" it as string and expect PHP to
> convert it *implicitly* later on, because one may well have cases where
> there is a string like "42" or "2foo" which is supposed to remain a
> string and be treated as a string and not as a number.
>

   PHP doesn't just randomly decide to type juggle, it does so in 
context. If you want a string "42", you have it. PHP won't do anything 
to it until you try to do some math with it (or explicitly ask it to do so.)

>> FORM data, GET/POST data, all strings...
>
> I heard you the first time.
>
>>>>>>>    switch ($mode) {
>>>>>>>      case SORT_ASC:
>>>>>>>      case SORT_DESC:
>>>>>>>      case SORT_REGULAR:
>>>>>>>      case SORT_NUMERIC:
>>>>>>>      case SORT_STRING:
>>>>>>>      case SORT_LOCALE_STRING:
>>>>>>>      case SORT_NATURAL:
>>>>>>>      case SORT_FLAG_CASE:
>>>>>>>        break;
>>>>>>>      default:
>>>>>>>        throw new \InvalidArgumentException("invalid sort mode:
>>>>>>> $mode");
>>>>>>>    }
>>>>>
>
>>> No I'm not assuming that. If all the SORT_* constants are integers, then
>>> only the default branch should match in that case. It doesn't in PHP,
>>> because PHP is made to implicitly convert strings to integers.
>>
>>   No, the only time the default is reached is when $mode is outside 0-7
>
> I wrote "in that case" referring to $mode = "foo".
>
>> (I say that because i only have 6 of the 8, I haven't updated yet.) If
>> $mode = E_ERROR it still validates. This code does nothing to ensure
>> $mode is what it is supposed to be.
>
> Yes, different constants could have the same value and there is no way
> for PHP to tell which one was "used" to pass the value. So you could
> pass E_ERROR instead of SORT_FOO if both happen to have the same value.
> It would be nice, though, to be able to detect that.
>
>>
>> What about:
>> -- code --
>> $mode = setSortMode("SORT_NUMERIC");
>> echo $mode."\n";
>
> That would be a workaround to achieve the above. But I find it not very
> elegant to use a string in this case.
>
>>   Technically speaking, the user should not be able to *choose* an
>> invalid mode but if they somehow did, I believe it should default to
>> some normal behavior (even if the result isn't what they wanted.) In
>> other words, default to SORT_REGULAR (pick your poison) until another
>> *valid* option is chosen.
>
> Or the code should throw an exception if an invalid argument is passed.
> (After all, it's the programmer's job to ensure no invalid arguments are
> passed to any function, so if it happens, it's the programmer's fault
> and must be fixed.)
>
>>> I am aware of the fact that PHP will try to convert the string into a
>>> number (even when this would not possibly make any sense).
>>
>> How do you know when it wouldn't make sense?
>
> Trying to convert "foo" to a number doesn't make sense. It only makes
> sense when the string contains the representation of a number.

   Thomas, methinks you've decided to be dense... PHP has to *look* at 
the string to determine that.

> That said, if there happened to be a defined constant foo = 42, then (int)
> "foo" could reasonably result in int(42). But in any case, a conversion


   There is no constant "foo". If created, it would be foo. So, no 
(int)"foo" should not result in a constant foo value. constant("foo") 
does that just fine.

> from string to number should never happen implicitly -- only explicitly.
>

   PHP type juggles when you ask it to do so (right/wrong/mistake). If 
it did it implicitly then it would happen before you ever got to the data.

>> FORMS, GET/POST data = strings...
>
> I heard you the first time.
>
> But just to be clear, let me repeat myself once more: *explicit*
> conversion from string to number is okay as long as it returns `null`

"foo" + 2 = 2
NULL + 2 = 2

> (or some other appropriate indication) in case of the string not
> representing a valid number. *Implicit* conversion from string to number
> is bad. Whenever there's a string and a number and PHP is supposed to do
> something with them (like comparing via `<=`), it should convert the
> number to a string and not the other way round.
>
> Greetings,
> Thomas
>


-- 
Norman
Registered Linux user #461062
-Have you been to www.php.net yet?-

Back to comp.lang.php | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 06:55 +0200
  Re: switch with case 0 "J.O. Aho" <user@example.net> - 2013-08-17 08:35 +0200
    Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 08:29 +0100
    Re: switch with case 0 Luuk <luuk@invalid.lan> - 2013-08-17 09:51 +0200
    Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 13:16 +0200
      Re: switch with case 0 "Peter H. Coffin" <hellsop@ninehells.com> - 2013-08-17 10:56 -0500
        Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 17:45 +0100
          Re: switch with case 0 Tim Streater <timstreater@greenbee.net> - 2013-08-17 18:58 +0100
            Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 19:39 +0100
              Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 21:36 +0200
        Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 22:14 +0200
      Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 13:56 -0400
        Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 21:55 +0200
          Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 21:04 +0100
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 22:32 +0200
              Re: switch with case 0 Richard Yates <richard@yatesguitar.com> - 2013-08-17 15:20 -0700
            Re: switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 22:37 +0200
              Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 19:26 -0400
              Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-18 12:54 +0100
          Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 20:23 -0400
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-18 15:22 +0200
              Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 11:20 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-18 18:28 +0200
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 15:16 -0400
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 18:04 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 00:17 +0200
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 00:13 +0200
                Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-19 00:35 +0100
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-19 06:30 -0400
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 22:13 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 19:55 +0200
          Re: switch with case 0 Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-08-19 10:18 +0200
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 19:39 +0200
  Re: switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 16:15 +0200
  Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 13:28 -0400

csiph-web