Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Tjerk Meesters]

On 21 Mar, 2013, at 2:08 AM, Carlos Rodrigues carlos.v...@gmail.com wrote:

 Hi,
 
 I'd like to suggest a new functionality for PHP. I don't know the
 internals, and i can't create a patch implementing this. I'm writing
 here in case someone likes this idea and write a RFC.
 
 We've had a problem recently where one of our developers forgot an if.
 
 So instead of writing
 if ($obj-image) {
 echo $obj-image-getUrl();
 }
 
 He wrote:
 echo $obj-image-getUrl();
 
 Here, locally, it was working cause we had the image. But when we
 updated the online version we got a Fatal error: Call to a member
 function getUrl() on a non-object cause someone didn't upload the
 image in one of the records that we're on the home page.
 
 Fatal errors like this can't be catched by a try/catch. And since this
 getUrl() was not essential for the page, we'd better output an empty
 string then having the site offline.

You can register a shutdown function with register_shutdown_function() and 
check for error_get_last() inside. 

In most cases you can't really handle this particular error very well anyway. 
At least with this you can have the full error emailed to you if you wish and 
print some kind of error message on the page. 

 
 One might say: you guys should have tested it better, or The image
 field should be mandatory in the back end.
 And it's true, he should have written that extra if {}.
 
 Examining this problem we happened to stumble open Ruby's and
 Coffescript's method check.
 Something like this:
 
 $obj-image?-getUrl()?;
 
 So my suggestion is:
 
 Create something like $foo-bar?() or $foo-bar()?, where you don't
 care whether the function exists, or if $foo is an object. If it
 doesn't exist you just return null.
 I guess there are plenty of systems out there where it's better to
 output an empty string than having your site offline, just cause the
 programmer couldn't test it completely.
 
 Thanks for reading it.
 
 Carlos Rodrigues
 
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[PHP-DEV] Method check - Can someone create a RFC for it?

[Carlos Rodrigues]

Hi,

I'd like to suggest a new functionality for PHP. I don't know the
internals, and i can't create a patch implementing this. I'm writing
here in case someone likes this idea and write a RFC.

We've had a problem recently where one of our developers forgot an if.

So instead of writing
if ($obj-image) {
echo $obj-image-getUrl();
}

He wrote:
echo $obj-image-getUrl();

Here, locally, it was working cause we had the image. But when we
updated the online version we got a Fatal error: Call to a member
function getUrl() on a non-object cause someone didn't upload the
image in one of the records that we're on the home page.

Fatal errors like this can't be catched by a try/catch. And since this
getUrl() was not essential for the page, we'd better output an empty
string then having the site offline.

One might say: you guys should have tested it better, or The image
field should be mandatory in the back end.
And it's true, he should have written that extra if {}.

Examining this problem we happened to stumble open Ruby's and
Coffescript's method check.
Something like this:

$obj-image?-getUrl()?;

So my suggestion is:

Create something like $foo-bar?() or $foo-bar()?, where you don't
care whether the function exists, or if $foo is an object. If it
doesn't exist you just return null.
I guess there are plenty of systems out there where it's better to
output an empty string than having your site offline, just cause the
programmer couldn't test it completely.

Thanks for reading it.

Carlos Rodrigues

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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Patrick ALLAERT]

2013/3/20 Carlos Rodrigues carlos.v...@gmail.com:
 Hi,

 I'd like to suggest a new functionality for PHP. I don't know the
 internals, and i can't create a patch implementing this. I'm writing
 here in case someone likes this idea and write a RFC.

 We've had a problem recently where one of our developers forgot an if.

 So instead of writing
 if ($obj-image) {
 echo $obj-image-getUrl();
 }

 He wrote:
 echo $obj-image-getUrl();

 Here, locally, it was working cause we had the image. But when we
 updated the online version we got a Fatal error: Call to a member
 function getUrl() on a non-object cause someone didn't upload the
 image in one of the records that we're on the home page.

 Fatal errors like this can't be catched by a try/catch. And since this
 getUrl() was not essential for the page, we'd better output an empty
 string then having the site offline.

 One might say: you guys should have tested it better, or The image
 field should be mandatory in the back end.
 And it's true, he should have written that extra if {}.

 Examining this problem we happened to stumble open Ruby's and
 Coffescript's method check.
 Something like this:

 $obj-image?-getUrl()?;

 So my suggestion is:

 Create something like $foo-bar?() or $foo-bar()?, where you don't
 care whether the function exists, or if $foo is an object. If it
 doesn't exist you just return null.
 I guess there are plenty of systems out there where it's better to
 output an empty string than having your site offline, just cause the
 programmer couldn't test it completely.

That's syntactic sugar we can live without as it does not really
encourage good programming practices.
If you don't care about those, then you can already just do:

echo @$obj-image-getUrl();

Patrick

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RE: [PHP-DEV] Method check - Can someone create a RFC for it?

[nathan]

 Hi,
 
 I'd like to suggest a new functionality for PHP. I don't know the
internals, and i can't create a patch implementing this. I'm writing here in
case someone likes this idea and write a RFC.
 
 We've had a problem recently where one of our developers forgot an if.
 
 So instead of writing
 if ($obj-image) {
 echo $obj-image-getUrl();
 }
 
 He wrote:
 echo $obj-image-getUrl();
 
 Here, locally, it was working cause we had the image. But when we updated
the online version we got a Fatal error: Call to a member function getUrl()
on a non-object cause someone didn't upload the image in one of the records
that we're on the home page.
 
 Fatal errors like this can't be catched by a try/catch. And since this
 getUrl() was not essential for the page, we'd better output an empty
string then having the site offline.
 
 One might say: you guys should have tested it better, or The image
field should be mandatory in the back end.
 And it's true, he should have written that extra if {}.
 
 Examining this problem we happened to stumble open Ruby's and
Coffescript's method check.
 Something like this:
 
 $obj-image?-getUrl()?;
 
 So my suggestion is:
 
 Create something like $foo-bar?() or $foo-bar()?, where you don't care
whether the function exists, or if $foo is an object. If it doesn't exist
you just return null.
 I guess there are plenty of systems out there where it's better to output
an empty string than having your site offline, just cause the programmer
couldn't test it completely.
 
 Thanks for reading it.
 
 Carlos Rodrigues
I do not like this idea. The error message Fatal error: Call to a member
function getUrl() on a non-object is very straight forward, it should tell
you the line the problem is on and everything and a quick glance should spot
the problem quickly. Granted Yes there are cases were it'd be nice to have
an easy work around, but then you run into the problem similar to what the @
has caused for many people, which libraries and general developers start
using it in many places to keep errors form being thrown and you end up with
code that is even harder to debug because no errors are shown. Another
solution that you could have used is to set $obj-image to a singleton
object that is a placeholder for methods like this which might be set...
something like: http://3v4l.org/utBWP

see: http://www.php.net/manual/en/language.oop5.overloading.php#object.call

But even that is a terrible solution, by showing the error fixed a bug...
bugs need to be fixed.


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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Carlos Rodrigues]

Like Mike emaild me, i can just change my code to something like
$obj-getImage()-getUrl(), where getImage() will return a mock object
with getUrl() returning an empty string.

But my request here is not about this case only.
Imagine you have a web page with 3 blocks of information. Let's say
news, partners and blog.

Now if for some reason you didn't code it right, you might get a fatal
error in one of these blocks.

I'd love to have a way to try/catch these blocks, Currently i can only
do this using ajax, or running shell exec php block.php for each
one.

If we could catch fatal errors, or at least the Call to a member
function on a non-object, we could have this code in our Zend
Framework implementations, wrapping each view in a try/catch, and
showing a error, sorry, in case the view has errors.

- Carlos

On Wed, Mar 20, 2013 at 3:33 PM, Carlos Rodrigues carlos.v...@gmail.com wrote:
 Thx for your reply Patrick,

 I agree that it's partially syntactic sugar, as you said. But when you do 
 this:

 $obj = new stdClass();
 echo $obj-foo;

 PHP will not if foo is not declared. It will output an empty string.
 But if you have a method

 echo @$obj-foo();
 echo 'end';

 It will give you a fatal error.

 Even using @ to suppress error messages it won't echo the 'end' part.

 Since short array syntax (like [1,2]) was not extremely necessary and
 was accepted, maybe someones has a better idea than i had to address
 this.

 Carlos

 On Wed, Mar 20, 2013 at 3:22 PM, Patrick ALLAERT patrickalla...@php.net 
 wrote:
 2013/3/20 Carlos Rodrigues carlos.v...@gmail.com:
 Hi,

 I'd like to suggest a new functionality for PHP. I don't know the
 internals, and i can't create a patch implementing this. I'm writing
 here in case someone likes this idea and write a RFC.

 We've had a problem recently where one of our developers forgot an if.

 So instead of writing
 if ($obj-image) {
 echo $obj-image-getUrl();
 }

 He wrote:
 echo $obj-image-getUrl();

 Here, locally, it was working cause we had the image. But when we
 updated the online version we got a Fatal error: Call to a member
 function getUrl() on a non-object cause someone didn't upload the
 image in one of the records that we're on the home page.

 Fatal errors like this can't be catched by a try/catch. And since this
 getUrl() was not essential for the page, we'd better output an empty
 string then having the site offline.

 One might say: you guys should have tested it better, or The image
 field should be mandatory in the back end.
 And it's true, he should have written that extra if {}.

 Examining this problem we happened to stumble open Ruby's and
 Coffescript's method check.
 Something like this:

 $obj-image?-getUrl()?;

 So my suggestion is:

 Create something like $foo-bar?() or $foo-bar()?, where you don't
 care whether the function exists, or if $foo is an object. If it
 doesn't exist you just return null.
 I guess there are plenty of systems out there where it's better to
 output an empty string than having your site offline, just cause the
 programmer couldn't test it completely.

 That's syntactic sugar we can live without as it does not really
 encourage good programming practices.
 If you don't care about those, then you can already just do:

 echo @$obj-image-getUrl();

 Patrick

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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Sanford Whiteman]

 Create something like $foo-bar?() or $foo-bar()?, where you don't
 care whether the function exists, or if $foo is an object. If it
 doesn't exist you just return null.

[1] Don't do this.

[2] What everyone else said.

[3] If you feel you must, this at least colors within the lines a
bit more than '@' by forcing you to set a class as wildcard-able:

class bitbucket {
function __call($name,$arguments){
return default value;
}
function __get($name){
return new self;
}
}

class myClass extends bitbucket {}

$myInst = new MyClass;
print $myInst-noExist-nexistePas(); // default value

[4] Goto [1].

-- S.


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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Matt Pelmear]

On 03/20/2013 11:43 AM, Carlos Rodrigues wrote:

Like Mike emaild me, i can just change my code to something like
$obj-getImage()-getUrl(), where getImage() will return a mock object
with getUrl() returning an empty string.

But my request here is not about this case only.
Imagine you have a web page with 3 blocks of information. Let's say
news, partners and blog.

Now if for some reason you didn't code it right, you might get a fatal
error in one of these blocks.

I'd love to have a way to try/catch these blocks, Currently i can only
do this using ajax, or running shell exec php block.php for each
one.

If we could catch fatal errors, or at least the Call to a member
function on a non-object, we could have this code in our Zend
Framework implementations, wrapping each view in a try/catch, and
showing a error, sorry, in case the view has errors.

- Carlos



Carlos,

You should take a look at the other thread that's been in the internals 
group over the last day or so. There is an effort to see cases like this 
become E_RECOVERABLE_ERRORs, which I think would address what you're 
really looking for. (In fact, this particular error is mentioned first 
in that thread.)


But I would argue that, while this is a change I support, this is not a 
substitute for proper testing prior to code deployment (as others have 
pointed out).


-Matt

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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Johannes Schlüter]

Carlos Rodrigues carlos.v...@gmail.com wrote:
So instead of writing
if ($obj-image) {
echo $obj-image-getUrl();
}

He wrote:
echo $obj-image-getUrl();

Make the property private and add a getter which can throw an exception if no 
image is available ...

class C {
private $image;
public function hasImage() { return (bool)$this-image; }
public function getImage() { if (!$this-image) { throw new 
NoImageException(); } return $this-image; }
}
echo $obj-geImage()-getUrl(); // Exception which can be caught.

No nee dto change the language and add a new cosntruct (which your developer 
will forget, if he forgets the if already )

johannes

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AW: [PHP-DEV] Method check - Can someone create a RFC for it?

[Frank Liepert]

 -Ursprüngliche Nachricht-
 Von: Carlos Rodrigues [mailto:carlos.v...@gmail.com]
 Gesendet: Mittwoch, 20. März 2013 19:08
 An: internals@lists.php.net
 Betreff: [PHP-DEV] Method check - Can someone create a RFC for it?
 
 Hi,
 
 I'd like to suggest a new functionality for PHP. I don't know the
 internals, and i can't create a patch implementing this. I'm writing
 here in case someone likes this idea and write a RFC.
 
 We've had a problem recently where one of our developers forgot an
 if.
 
 So instead of writing
 if ($obj-image) {
 echo $obj-image-getUrl();
 }
 
 He wrote:
 echo $obj-image-getUrl();
 
 Here, locally, it was working cause we had the image. But when we
 updated the online version we got a Fatal error: Call to a member
 function getUrl() on a non-object cause someone didn't upload the
 image in one of the records that we're on the home page.
 
 Fatal errors like this can't be catched by a try/catch. And since this
 getUrl() was not essential for the page, we'd better output an empty
 string then having the site offline.
 
 One might say: you guys should have tested it better, or The image
 field should be mandatory in the back end.
 And it's true, he should have written that extra if {}.
 
 Examining this problem we happened to stumble open Ruby's and
 Coffescript's method check.
 Something like this:
 
 $obj-image?-getUrl()?;
 
 So my suggestion is:
 
 Create something like $foo-bar?() or $foo-bar()?, where you don't
 care whether the function exists, or if $foo is an object. If it
 doesn't exist you just return null.
 I guess there are plenty of systems out there where it's better to
 output an empty string than having your site offline, just cause the
 programmer couldn't test it completely.
 
 Thanks for reading it.
 
 Carlos Rodrigues
 
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Just one question: Is your developer a template designer?



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Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Pierre du Plessis]

On 03/20/2013 11:43 AM, Carlos Rodrigues wrote:

  Like Mike emaild me, i can just change my code to something like
 $obj-getImage()-getUrl(), where getImage() will return a mock object
 with getUrl() returning an empty string.

 But my request here is not about this case only.
 Imagine you have a web page with 3 blocks of information. Let's say
 news, partners and blog.

 Now if for some reason you didn't code it right, you might get a fatal
 error in one of these blocks.

 I'd love to have a way to try/catch these blocks, Currently i can only
 do this using ajax, or running shell exec php block.php for each
 one.

 If we could catch fatal errors, or at least the Call to a member
 function on a non-object, we could have this code in our Zend
 Framework implementations, wrapping each view in a try/catch, and
 showing a error, sorry, in case the view has errors.

 - Carlos


 Carlos,

 You should take a look at the other thread that's been in the internals
 group over the last day or so. There is an effort to see cases like this
 become E_RECOVERABLE_ERRORs, which I think would address what you're really
 looking for. (In fact, this particular error is mentioned first in that
 thread.)

 But I would argue that, while this is a change I support, this is not a
 substitute for proper testing prior to code deployment (as others have
 pointed out).


I think changing the fatal error to E_RECOVERABLE_ERROR will be a good
option, because if you have a generic error handler, then you won't have to
worry about blank pages on a production server

Re: [PHP-DEV] Method check - Can someone create a RFC for it?

[Stas Malyshev]

Hi!

 We've had a problem recently where one of our developers forgot an if.

We clearly have two contradicting directions here. On one hand, we have
people that say giving '1' to a method expecting integer should be an
error, and anything unexpected should generate warnings and errors
because the code should handle exceptional cases explicitly.

On the other hand, we have people who say no matter what happens, just
plow through and substitute nulls if something is wrong.

Both approaches I guess have their advocates and their fans, and have
good pro and contra arguments. What however I think can not be done is
randomly taking both of these approaches in one language at a whim and
expect it to make sense. PHP has taken enough criticism on this front
and we don't need to add more to it. Either we say if the call can't be
done it's an error or we say if we can't call something we just return
null but not both. PHP currently treats methods that can't be called as
an error. I think replacing it with just return null would not be a
thing most PHP developers would want.

-- 
Stanislav Malyshev, Software Architect
SugarCRM: http://www.sugarcrm.com/
(408)454-6900 ext. 227

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