[Fwd: [PHP] constant() - php5]

20 years ago by Jochem Maas — view source — reply

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hi,

I just wanted to say about 'include' ... er no actually
I have this little thing with constant() which I asked about
on php-generals and the response from a couple of regulars
suggest it might be a bug, or more correctly, an inconsistency.

Jason Barnett wrote also:

tested with PHP 5.0.5-dev

<?php

/* Causes E_WARNING */
echo "constant('UNDEFINED_CONSTANT')\n";
echo constant('UNDEFINED_CONSTANT');

/* Causes E_NOTICE */
echo "UNDEFINED_CONSTANT\n";
echo UNDEFINED_CONSTANT;

?>

should(may) I submit a bugreport?

-------- Original Message --------
anybody here know what the logic is behind constant() triggering a warning
if the named constant is not found?

contrived example:

$cnst = "DEBUG";

// what I want to do but can't
if ($dbg = constant($cnst)) {
// do stuff
}

// the only real option, it seems - bit long winded to get round a stupid (IMHO)
if (defined($cnst) && ($dbg = constant($cnst))) {
// do stuff
}

PLEASE - nobody need bother to tell me about the @ operator, I am
aware of it but I don't want to use it in this case. (addition: not for a warning)

thanks & rgds,
jochem

20 years ago by Jochem Maas — view source — reply

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Pawel Bernat wrote:

<?

$cnst = "DEBUG";

// what I want to do but can't
if ($dbg = constant($cnst)) {
// do stuff
}

// the only real option, it seems - bit long winded to get round a stupid (IMHO)
if (defined($cnst) && ($dbg = constant($cnst))) {
// do stuff
}

What is stupid with validating name before using it?

its inconsistent to trigger an E_WARNING when doing:

echo constant('CNST');

when:

echo CNST;

only triggers an E_NOTICE.
(assuming, in both cases that CNST is not defined).

IMHO it should at most trigger an E_NOTICE.

p.

20 years ago by Derick Rethans — view source — reply

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echo constant('CNST');

when:

echo CNST;

only triggers an E_NOTICE.
(assuming, in both cases that CNST is not defined).

IMHO it should at most trigger an E_NOTICE.

Did you compare the output of the two statements?
echo constant('CNST');
shows nothing (except the warning)

echo CNST;
shows "CNST" (and a notice).

This makes perfect sense to me to differentiate between them like this.

Derick

--
Derick Rethans
http://derickrethans.nl | http://ez.no | http://xdebug.org

20 years ago by Jochem Maas — view source — reply

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Derick Rethans wrote:

echo constant('CNST');

when:

echo CNST;

only triggers an E_NOTICE.
(assuming, in both cases that CNST is not defined).

IMHO it should at most trigger an E_NOTICE.

Did you compare the output of the two statements?

I did.

echo constant('CNST');
shows nothing (except the warning)

echo CNST;
shows "CNST" (and a notice).

This makes perfect sense to me to differentiate between them like this.

ok - agreed that the echo behaviour is logical - but I wasn't actually
pertaining to the echo behaviour (and what was being echo'ed wasn't relevant to my
original question).

my point is that using a constant directly in your code when that constant doesn't exist
only causes an E_NOTICE but passing a string to constant() when a constant of the given
name doesn't exist causes an E_WARNING.

I would either expect both to cause the same level of error OR that trying to
use an undefined constant directly in code would cause a lower level of error.

but if you say the error output behaviour is expected/correct/desired then I'm
happy to except it (and adjust my expectations accordingly)

if you (anyone) could explain why (because I don't grok the logic behind
this behaviour) I would be very grateful, maybe it will bring me one step closer
to being able to call myself a real programmer. :-/

anyway thanks for taking the time to reply,
I gather that you, Derick (amongst others!), have a plate full of PHP work
in the form of unicode and date related stuff (which I am very much looking
forward to!) - i.e. you are busy-busy, time is short, etc etc.

kind rgds,
Jochem

Derick

20 years ago by Nicholas Telford — view source — reply

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Due to PHPs dynamic typing, unquoted strings are treated as strings
unless a constant by that name exists. Thankfully it's clever enough to
raise a notice to tell you it couldn't find a constant by that name,
which makes debugging much easier.

The reason constant() throws a warning rather than a notice is because
PHP knows you're looking for a constant by that name and flags it as a
more serious error, wheras before, it could just be that you want to use
an unquoted string :)

If you think it's a bit strange, it may seem so, but logically, if an
unquoted number is equivilent to it's quoted counter-part, the same must
be true for strings.

Nicholas Telford

Jochem Maas wrote:

Derick Rethans wrote:

echo constant('CNST');

when:

echo CNST;

only triggers an E_NOTICE.
(assuming, in both cases that CNST is not defined).

IMHO it should at most trigger an E_NOTICE.

Did you compare the output of the two statements?

I did.

echo constant('CNST');
shows nothing (except the warning)

echo CNST;
shows "CNST" (and a notice).

This makes perfect sense to me to differentiate between them like this.

ok - agreed that the echo behaviour is logical - but I wasn't actually
pertaining to the echo behaviour (and what was being echo'ed wasn't
relevant to my
original question).

my point is that using a constant directly in your code when that
constant doesn't exist
only causes an E_NOTICE but passing a string to constant() when a
constant of the given
name doesn't exist causes an E_WARNING.

I would either expect both to cause the same level of error OR that
trying to
use an undefined constant directly in code would cause a lower level of
error.

but if you say the error output behaviour is expected/correct/desired
then I'm
happy to except it (and adjust my expectations accordingly)

if you (anyone) could explain why (because I don't grok the logic behind
this behaviour) I would be very grateful, maybe it will bring me one
step closer
to being able to call myself a real programmer. :-/

anyway thanks for taking the time to reply,
I gather that you, Derick (amongst others!), have a plate full of PHP work
in the form of unicode and date related stuff (which I am very much looking
forward to!) - i.e. you are busy-busy, time is short, etc etc.

kind rgds,
Jochem

Derick