Sometimes this is true, but sometimes not. For example, HTTP GET/POST interfaces
often have optional parameters. These need to be tested for, and often defaults
provided, to write solid code.
Saying you can always wrap it is like saying you can write your programs for a
Turing machine.
Also, not everyone is writing highly abstracted object-oriented code in PHP.
Ben.
On 14/04/11 11:25 PM, Martin Scotta wrote:
arrays are intent for holding values, not for represent things so use objects
for
that.
the need for array_key_exists/isset to check for the presence of an index is a
smell that you need to refactor your code for a different datatype.
If you cannot change the array, you always can wrap it.
With good data abstractions the usage of array_key_exists/isset/empty is barely
reduced to the minimum.
Martin Scotta
On Thu, Apr 14, 2011 at 10:12 AM, Ben Schmidt <mail_ben_schm...@yahoo.com.au
<mailto:mail_ben_schm...@yahoo.com.au>> wrote:
There are two issues here.
1. Suppression of notice. I agree, it is best done only
for array
keys. It's not hard to initialise a variable with
$var=null at the
beginning of a code block to avoid such a notice, and
that
is the
appropriate way to do it for variables.
2. Offering a shortcut for the common idiom isset($x) ?
$x
: $y in
line with the DRY design principle. A notice would never
be emitted
here in any case. The problem is that this idiom is
still
in wide use
despite the shortcut ternary operator already provided,
because an
isset() check is different to a boolean cast.
Some thoughts:
- The actual intent of 2. is probably $x!==null ? $x :
$y
i.e. it's
not about suppressing notices at all, but about
offering
a default
value, and the idiom quite probably only uses isset()
because it
predated null in the language.
- If we view 2. in this way, the two problems are
independent, and it
seems to me it would be best to solve them
independently, rather
than with a single operator.
So, I suggest:
1. An array lookup mechanism that suppresses the notice
for undefined
keys. It would work the same as regular array index
lookups except
that the notice for undefined keys (and only for
undefined
keys)
would not be generated (it would not just be hidden, but
would never
be even generated).
http://news.php.net/php.internals/51877
array_key_exists($key, $array) for arrays
array_key_exists($varname, get_defined_vars()) for locally scoped
variables.
Apart from being long and ugly, surely that is horribly inefficient.
No need to use @.
True. And I don't think anybody is. We all know @ is dangerous and nasty
and don't use it. We're not seeking an alternative to @, we're seeking
an alternative to repeating ourselves by using
isset()/array_key_exists()/is_null() as well as the value being tested.
But we don't want to do this in a blanket way similar to @ where a whole
bunch of notices are suppressed. We want to specify precisely where
missing values are allowable by indicating exactly which array index
lookups may silently fail (and evaluate to null).
Basically we don't want to make again the mistake that @ was.
Are they attempting to determine the existence of a variable/index
entry or are they attempting to determine if the variable/element is
null.
For me, existence and nullness are basically the same, and I think this
is the common case. The whole point of being able to set something to
null is to have a 'value' to represent 'unsetness'. This is why I think
solving the conditional problem should use a !==null test. That gives
the flexibility to use/pass null to represent 'unsetness' but doesn't
pick up zero, false, etc. like a boolean cast does. Using
array_key_exists() would remove that flexibility and be less useful.
As far as silencing notices goes, the rationale is that basically we
want to flag that 'null is OK, even if it's a fallback'. I.e. we don't
care whether a value is null because it was set to null, or because null
is a fallback because the variable was never defined. Either way, null
is OK, so don't tell me about it.
The conditional side lets us handle nulls nicely by providing our own
defaults/fallbacks if it appears. The notice-suppression side lets us
say that null is OK, even if that null itself is a fallback for
'undefined'. Quite often they will be used in combination, but they are
independent.
I always declare my variables. So, I don't want to use isset() as they
will be an incorrect test. I use is_null(). Specifically testing the
value. If I've made a mistake and NOT declared the variable (or made a
typo), I want to know. I don't want to hide it with isset()/empty().
That's exactly why I think the conditional should use a !==null test,
not an isset() test.
Ben.
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