RE: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
But I think it looks a bit cleaner if the variable could be omitted, if it's not needed ;-) I don't think we need to change the language because Netbeans can't figure out how catch blocks work. The Netbeans thing was just an example/addition. It's not used by you - which btw is usually not a good idea - if you've got an exception, you usually should somehow react to it - at least log it or something, that's what the exceptions are for, if the situation does not require special handling it shouldn't be an exception. But it If you have an exception like `BadCredentialsException` and throw it during authentication if the user has entered wrong login data, than you have such a situation right? But do you need any further information? No - in the catch block it may be enough to create a message for the user saying: wrong username or password. Maybe you only use generic exceptions like `RuntimeException`. This can be an exception for almost everything. But if you have defined an exception for one special case, to interrupt your code, and catch such an exception you will always know why this exception has been thrown. -- Christian Stoller LEONEX Internet GmbH
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On 25 June 2013 22:23, Johannes Schlüter johan...@schlueters.de wrote: On Tue, 2013-06-25 at 13:19 -0700, Stas Malyshev wrote: Hi! If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation Well, here we go - this is why not add it, because it makes working with such code harder without actually benefiting anybody. +1 Right now I set a breakpoint in my editor and look at an exception even if it is not used, in future I'd have to change the code for that. Hrm, this is a very good point! So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?. Why not is usually not a very good principle of language design, IMO. Nothing more to add. -- Regards, Mike -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On Wed, Jun 26, 2013 at 8:31 AM, Christian Stoller stol...@leonex.de wrote: But I think it looks a bit cleaner if the variable could be omitted, if it's not needed ;-) I don't think we need to change the language because Netbeans can't figure out how catch blocks work. The Netbeans thing was just an example/addition. It's not used by you - which btw is usually not a good idea - if you've got an exception, you usually should somehow react to it - at least log it or something, that's what the exceptions are for, if the situation does not require special handling it shouldn't be an exception. But it If you have an exception like `BadCredentialsException` and throw it during authentication if the user has entered wrong login data, than you have such a situation right? But do you need any further information? No - in the catch block it may be enough to create a message for the user saying: wrong username or password. Maybe you only use generic exceptions like `RuntimeException`. This can be an exception for almost everything. But if you have defined an exception for one special case, to interrupt your code, and catch such an exception you will always know why this exception has been thrown. -- Christian Stoller LEONEX Internet GmbH Hi, I believe that the example you provided, the one with 'BadCredentialsException', is a good example of a bad design and usage of exceptions, at least from my point of view. The fact that frameworks like Symfony2, Zend Framework or other php libraries/frameworks (ab)use the exceptions it doesn't mean that it's a good thing or you should have exceptions for everything. The provided example could just as well return false; for the login function and that's it, no? Exceptions should be used for exceptional cases where the application can't recover automatically from them. They are, even as their name suggests, exceptional cases, while a bad credential for a user login is not :) I also believe, and I might not be the only one with this, that exceptions used for flow control is a good sign of bad design. If you follow this way of thinking, everytime you throw an exception, you would want to catch it and perform some work with it, like logging it for example. So why would you make the variable optional then? Best regards Florin Patan https://github.com/dlsniper http://www.linkedin.com/in/florinpatan -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On 26 juni 2013 at 08:35:59, Michael Wallner (m...@php.net) wrote: On 25 June 2013 22:23, Johannes Schlüter johan...@schlueters.de wrote: On Tue, 2013-06-25 at 13:19 -0700, Stas Malyshev wrote: Hi! If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation Well, here we go - this is why not add it, because it makes working with such code harder without actually benefiting anybody. +1 Right now I set a breakpoint in my editor and look at an exception even if it is not used, in future I'd have to change the code for that. Hrm, this is a very good point! So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?. Why not is usually not a very good principle of language design, IMO. Nothing more to add. -- Regards, Mike This is a little pathetic. Someone sums it up to Why not, which is not the case, we have grounded arguments for this, and then all agree that Why not is not a reason to add something. Surely it isn't. You mention bad coding practices. Sure, we should avoid them. Unused variables is a bad coding practice. So, we should avoid them. Luckily, it's easy to avoid them with catch-statements, because we can simply make the variable optional. I recently wrote a CLI tool in C# to import data from Team Foundation Server. During an update, I try to download every new commits from where I last stopped (so, from commit latest+1). That fails with a ChangesetNotFoundException when no such commit exists, fair enough. I cannot test beforehand whether that exception will be thrown (that would mean I needed two calls to the server, now it's in one round) so it's totally expected. I'm doing this for 100.000 files and I don't want to do anything with the exception, it's nothing more than an indication that we're already up-to-date for that file. Done. In PHP I would have an unused variable, which trips up my static analysis tool that keeps warning me about the bad coding practice of having an unused variable. I agree, it's bad to have that variable defined but PHP won't let me get rid of it. Another reason for people to bitch about PHP. Luckily, we can do something about it, and it happens to be easy. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] Re: Announcing RFC 'Anonymous Catches'
Hi,
Another two cents here.
* Skipping binding a parameter to the exception would make debugging
harder. When you're stepping through code that isn't working correctly to
find a problem and then it throws an Exception which is caught in catch
block that doesn't name it e.g.
try
{
$connection = $this-connectToServer();
$data = $this-prepareData();
// lots more lines
// of code
$response = $this-getResponse();
$connection-close();
}
catch (UnexpectedException)
{
$this-retry(3);//breakpoint here, how to inspect Exception?
}
You can't actually inspect the caught exception, unless you knew where it
was going to be caught ahead of time, and went in to modify the code to
name the Exception before you started debugging.
* The RFC says Runtime needs to perform less checks. - I'm not an expert
on the performance cost of Exceptions but surely that must be irrelevant?
Exceptions should only happen in exceptional circumstances, so shaving a
couple of cycles from code that rarely gets called should not be a factor
in deciding this RFC.
* Throwing and catching raw \Exception classes is in general a bad pattern
and should only be rarely done, to avoid uncaught errors being shown to
end-users. It's a common anti-pattern for junior developers to catch (and
throw) \Exception rather than extending specific Exception classes for the
specific Exception that could occur.
I don't think we should be making it be the easier choice to write bad code
than to write good code.
I also don't think that it's a problem for someone coming from another
language to learn what the root Exception class is for a language. It's not
as if it's an obscure, hardly used part of the language - it's really quite
important.
Although not having to write the Exception type would make it easier for
some programmers to learn PHP, for people learning PHP as their first
language or people coming from other languages where the Exception type has
to be set, having the Exception type be optional would be one more thing to
learn.
Joost Koehoorn wrote:
the type of an exception mostly tells enough about what happened
I think that's only true when it's an 'expected' exception, e.g. the
ConnectionLostException from the RFC, where you almost always just want to
retry the operation.
When it's an unexpected exception e.g. caused by trying to read a corrupted
file, you almost always need to have at least log the message and in some
cases it is necessary to have additional information that can be presented
to the user in a nice format, rather than just the raw message itself. e.g.
class InsufficientCreditsException extends \Exception {
protected $creditsRequired;
public function __construct($creditsRequired, $message = null, $code =
0, Exception $previous = null){...}
}
allows an InsufficientCreditsException exception to bubble up from the call
to the external API all the way to the UI where '$creditsRequired' is
formatted nicely for the user.
Although with the RFC you could have each style of catch statement where
needed, having two different ways of writing catch statements would be
confusing when it doesn't need to be.
In summary, although this would make PHP easier to learn for a few people,
I think it makes debugging and writing good consistent code be harder, as
well as making PHP harder to learn for other people.
cheers
Dan
[PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
Hi all,
I just published an RFC that proposes to add catch-statement without needing
to specify a variable, and support for fully anonymous catches.
Details can be found at:
https://wiki.php.net/rfc/anonymous_catch
Regards,
Joost Koehoorn
Hi.
I am not sure about complete anonymous catch statement (like try { } catch {
}), but I really like the proposal for omitting the exception variable.
Because in frameworks like Symfony there are defined and used a lot of special
exception types for each cases.
Here's an example that shows what I mean:
try {
$foo-authenticate($user);
} catch (BadCredentialsException) {
echo Bad credentials;
} catch (InactiveAccount) {
echo Sorry, your account is not active anymore.;
} catch (CurlErrorOnAuthService) {
echo Please try again later, the login service is currently unavailable.;
} catch (Exception) {
echo bla blubb;
}
In such a case you do not need any `$e`variable. Netbeans for example always
highlight's these variables because it is not used anywhere. But I think it
looks a bit cleaner if the variable could be omitted, if it's not needed ;-)
Best regards
Christian
This is exactly the reason, yes!
As stated in the RFC, I think it's best that we consider the two ways
separately. Omitting the variable is a much smaller change (and requires very
little code changes) than having a fully anonymous catch.
I originally dived into this because of a question of Phil Sturgeon on twitter,
requesting for making the variable optional. I took it one step further and
made the whole thing optional, but surely we can decide to only make the
variable optional, I can see how it's bad programming practice to have fully
anonymous blocks (even though sometimes they may be used). Just throwing this
out here to see what you think about it.
Regards,
Joost
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Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
I, too, believes that omitting the exception variable is great.
In addition, anonymous catch blocks will shorten the code of catch
(Exception $e) so... is just a simpler way of writing - and that's what
PHP agenda aiming for, doesn't it? be a friendly and readable language.
Reading
try {
$foo-bar();
} catch {
show404Page();
}
For example, is readable, short and not contain any extra variables that we
didn't used.
On Tue, Jun 25, 2013 at 2:18 PM, Joost Koehoorn joost.koeho...@gmail.comwrote:
Hi all,
I just published an RFC that proposes to add catch-statement without
needing to specify a variable, and support for fully anonymous catches.
Details can be found at:
https://wiki.php.net/rfc/anonymous_catch
Regards,
Joost Koehoorn
Hi.
I am not sure about complete anonymous catch statement (like try { } catch
{ }), but I really like the proposal for omitting the exception variable.
Because in frameworks like Symfony there are defined and used a lot of
special exception types for each cases.
Here's an example that shows what I mean:
try {
$foo-authenticate($user);
} catch (BadCredentialsException) {
echo Bad credentials;
} catch (InactiveAccount) {
echo Sorry, your account is not active anymore.;
} catch (CurlErrorOnAuthService) {
echo Please try again later, the login service is currently
unavailable.;
} catch (Exception) {
echo bla blubb;
}
In such a case you do not need any `$e`variable. Netbeans for example
always highlight's these variables because it is not used anywhere. But I
think it looks a bit cleaner if the variable could be omitted, if it's not
needed ;-)
Best regards
Christian
This is exactly the reason, yes!
As stated in the RFC, I think it's best that we consider the two ways
separately. Omitting the variable is a much smaller change (and requires
very little code changes) than having a fully anonymous catch.
I originally dived into this because of a question of Phil Sturgeon on
twitter, requesting for making the variable optional. I took it one step
further and made the whole thing optional, but surely we can decide to only
make the variable optional, I can see how it's bad programming practice to
have fully anonymous blocks (even though sometimes they may be used). Just
throwing this out here to see what you think about it.
Regards,
Joost
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[PHP-DEV] Re: Announcing RFC 'Anonymous Catches'
On Tue, Jun 25, 2013 at 12:54 AM, Joost Koehoorn
joost.koeho...@gmail.com wrote:
Hi all,
I just published an RFC that proposes to add catch-statement without needing
to specify a variable, and support for fully anonymous catches.
Details can be found at:
https://wiki.php.net/rfc/anonymous_catch
Regards,
Joost Koehoorn
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To unsubscribe, visit: http://www.php.net/unsub.php
Hi,
First of, considering that you would only save three characters by
having the ' $e' removed, I don't see how it would make things easier
to learn. I mean if you can't learn that maybe you should look into
something else that's not related to programming :)
I don't recall mentioning that this makes PHP easier to learn. It's really
about avoiding introducing unused variables, which is currently required
because the language simply requires and identifier there.
Having this: * Avoid indication of a specific exception type could
be considered as a possible bad practice, just as you were saying that
catch(\Exception $e) is. Also, it you can add the other ten characters
that you save when typing \Exception but does it worth it?
I don't really care about saving a few characters, that's not what this is
about. I can see that a catch-all can be considered bad practice, but perform a
Github search for `catch (Exception $e)` and find very much instances of this
usage. In all of these situations it seems that only specific exceptions are
caught, but that's not actually the case. We currently see that requiring an
Exception type doesn't really enforce good programming practice, most instances
simply use `(\Exception $e)` and have the same bad practice.
How do you plan to handle this: * Note that there may only be one
anonymous catch-statement, and it has to be the last one. Throw a
fatal error? If not then what, nothing?
In my current implementation, it's simply a syntax error and thus will never
result in compiled code.
What are the performance downsides of having this check in place? I do
understand that you mentioned: * Runtime needs to perform less
checks. No need to update the symboltable, no need to check exception
inheritance. but wouldn't that be replaced by what I'm asking about?
If I could read/understand C better I wouldn't ask for this.
As it's directly enforced by the language grammer, Bison (the parser generator)
won't accept invalid use of the anonymous catch, and thus no additional runtime
checks are necessary.
Could you also please elaborate this: * Better possibilities for
static analysis tools?
This is about unused variables. When you use an IDE or tools such as PHPMD,
they will warn you about unused variables in your code. Exception variables are
simply required by the language, even though you may not actually use them,
thus generating unused variables warnings (or the analyser doesn't flag
exception variables, in which case you miss unused variables) which you cannot
solve.
As for: * People from other languages such as C#, Python and Ruby
expect this to work I think it is often pointed out when requesting
features such as function/method return type hinting (I'm planning a
RFC for that), named parameters, threads and other stuff that this
ain't C#, Java, Python, Ruby or whatnot so.. what's the official
position on this? Do we want PHP like the other languages or not (and
I won't say more on this here/now)?
I can agree with you here, PHP has its own things and is different from other
languages for a reason. I'm mentioning this because I can see how Python/Ruby
developers working with PHP may find this a flaw in PHP, giving them another
reason to bitch about PHP.
Also, the code sample is not that good. If you want to reflect a good
quality scenario, it should be more like:
while (true) {
try
{
$this-connectToServer();
break;
}
catch (ConnectionFailedException)
{
sleep(3);
}
}
And I think the RFC should also add a: Disadvantages section so that
it could help people looking on it and proving that you've done all
the research correctly.
I couldn't really come up with disadvantages. Anonymous catch-statements may be
considered bad coding practice, but look at the amount of developers simply
using `Exception` as the type which is the same bad practice, only with the
false indication that a specific type is expected. By allowing for not
specifying the type at all, it's immediately clear that the intention was to
not care about the type at all.
Thanks
Florin Patan
https://github.com/dlsniper
http://www.linkedin.com/in/florinpatan
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Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
Hi! In such a case you do not need any `$e`variable. Netbeans for example always highlight's these variables because it is not used anywhere. But I think it looks a bit cleaner if the variable could be omitted, if it's not needed ;-) I don't think we need to change the language because Netbeans can't figure out how catch blocks work. This change doesn't provide any functionality that wasn't available before it, and does not make the code clearer - on the contrary, IMO it makes debugging harder and people reading the code more confused. In PHP, we always valued clarity over brevity, and I think we should keep it this way. -- Stanislav Malyshev, Software Architect SugarCRM: http://www.sugarcrm.com/ (408)454-6900 ext. 227 -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On 25 June 2013 20:17, Stas Malyshev smalys...@sugarcrm.com wrote:
Hi!
I don't think we need to change the language because Netbeans can't
figure out how catch blocks work. This change doesn't provide any
functionality that wasn't available before it, and does not make the
code clearer - on the contrary, IMO it makes debugging harder and people
IMO actually it *makes* the code clearer, because $ignoredException is
not used, though a variable name like $ignored is self-explanatory,
too.
reading the code more confused. In PHP, we always valued clarity over
brevity, and I think we should keep it this way.
Duh, I find that statement a bit brave, though ;)
.oO(__{get,set,call,etc…}, object operators)
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Regards,
Mike
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Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
Hi! IMO actually it *makes* the code clearer, because $ignoredException is not used, though a variable name like $ignored is self-explanatory, too. It's not used by you - which btw is usually not a good idea - if you've got an exception, you usually should somehow react to it - at least log it or something, that's what the exceptions are for, if the situation does not require special handling it shouldn't be an exception. But it may be very useful for debugging, for example. Especially if somebody other than you looks at this code and tries to figure out what is going on. Removing vital information - like ability to see which exception was thrown - just to save 3 keystrokes - looks like a very misguided idea to me. -- Stanislav Malyshev, Software Architect SugarCRM: http://www.sugarcrm.com/ (408)454-6900 ext. 227 -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
Regarding all of the discussion about the unused variable: If your catch blocks are too long or too complicated to be able to tell that the variable is unused, then I highly suggest you refactor that section. --- To me, the only maybe-useful portion of this discussion would be the empty catch which is more clear that it is a final resort catch than just catching \Exception. Apparently the opinions on this are quite divided, though.
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On Tue, Jun 25, 2013 at 3:50 PM, Stas Malyshev smalys...@sugarcrm.comwrote: Hi! IMO actually it *makes* the code clearer, because $ignoredException is not used, though a variable name like $ignored is self-explanatory, too. It's not used by you - which btw is usually not a good idea - if you've got an exception, you usually should somehow react to it - at least log it or something, that's what the exceptions are for, if the situation does not require special handling it shouldn't be an exception. But it may be very useful for debugging, for example. Especially if somebody other than you looks at this code and tries to figure out what is going on. Removing vital information - like ability to see which exception was thrown - just to save 3 keystrokes - looks like a very misguided idea to me. Not to down-play the importance of what you're saying, since I fully agree with it, but he is saying that this isn't a key-stroke saving proposition. If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation this is one of those nice to have features that has little cost and very little benefit. And I'm referring only to making the Exception variable optional (not the anonymous catch -- I'm entirely opposed to that part). So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?.
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On 25 juni 2013 at 22:06:40, Sherif Ramadan (theanomaly...@gmail.com) wrote: On Tue, Jun 25, 2013 at 3:50 PM, Stas Malyshev smalys...@sugarcrm.com wrote: Hi! IMO actually it *makes* the code clearer, because $ignoredException is not used, though a variable name like $ignored is self-explanatory, too. It's not used by you - which btw is usually not a good idea - if you've got an exception, you usually should somehow react to it - at least log it or something, that's what the exceptions are for, if the situation does not require special handling it shouldn't be an exception. But it may be very useful for debugging, for example. Especially if somebody other than you looks at this code and tries to figure out what is going on. Removing vital information - like ability to see which exception was thrown - just to save 3 keystrokes - looks like a very misguided idea to me. Not to down-play the importance of what you're saying, since I fully agree with it, but he is saying that this isn't a key-stroke saving proposition. If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation this is one of those nice to have features that has little cost and very little benefit. And I'm referring only to making the Exception variable optional (not the anonymous catch -- I'm entirely opposed to that part). So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?. Correct. The tweet was actually a serious request and grounded (see http://news.php.net/php.webmaster/16092 as an earlier response to you). So the reason to make it optional is not really why not?, there is some reasoning behind it. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
Hi! If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation Well, here we go - this is why not add it, because it makes working with such code harder without actually benefiting anybody. So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?. Why not is usually not a very good principle of language design, IMO. -- Stanislav Malyshev, Software Architect SugarCRM: http://www.sugarcrm.com/ (408)454-6900 ext. 227 -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] RE: Announcing RFC 'Anonymous Catches'
On Tue, 2013-06-25 at 13:19 -0700, Stas Malyshev wrote: Hi! If I'm to understand this RFC correctly, it is nothing more than a random suggestion someone posed in the form of a tweet and the author is saying why not add it since it's not hard to implement. So in summation Well, here we go - this is why not add it, because it makes working with such code harder without actually benefiting anybody. +1 Right now I set a breakpoint in my editor and look at an exception even if it is not used, in future I'd have to change the code for that. So this entire discussion can be summed up nicely with Let's make the variable optional because... why not?. Why not is usually not a very good principle of language design, IMO. +100 johannes -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
[PHP-DEV] Re: Announcing RFC 'Anonymous Catches'
On 25 juni 2013 at 01:20:04, Anthony Ferrara (ircmax...@gmail.com) wrote:
Joost,
First off, let me say welcome and thanks for the contribution!
I have a couple of questions around the intended proposal.
1. How do you plan on handling the case where there are multiple catch blocks?
try {
code();
} catch {
doSomething();
} catch {
doSomethingElse();
}
As mentioned as latest sentence in the Proposal chapter, an anonymous catch can
only be used as the latest catch, and there can only be one of them. This is
also how my current implementation works.
2. You mention as a benefit Better possibilities for static analysis tools.
Can you elaborate on this? I don't see how this sort of a change would have any
effect (as catch would be the same as the existing `catch (\Exception $e)`)...
It's mostly for finding unused variables. I suppose that static analysers
currently ignore unused exception variables, but they don't have to when this
is accepted and can properly indicate unused exception variables.
3. What benefit short of not having to type `(\Exception $e)` would this have?
Populating the symbol table is extremely cheap at this stage, because the
variable is already compiled in (so no hash table lookup or anything).
Performance wise it's indeed very minor and doesn't really matter. It's more
that you're adding code indicating that only a specific exception is used,
while that may not really be the case.
Consider Java people --Java has Throwable as the superclass of Exception-- they
may not know that in PHP 'Exception' is the least-specific type and therefore
used as catch-all.
As for leaving of the variable, the type of an exception mostly tells enough
about what happened (well, it should), so you don't have to inspect the
exception's error code/message and thus don't need the exception object at all.
Additionally, I would recommend changing the version target to 5.NEXT (which
would be 5.6 in practice).
Done!
As far as my personal feelings, I'd like to get some other commentary first.
Thanks again!!!
Anthony
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Re: [PHP-DEV] Re: Announcing RFC 'Anonymous Catches'
On Mon, Jun 24, 2013 at 7:49 PM, Joost Koehoorn joost.koeho...@gmail.comwrote:
On 25 juni 2013 at 01:20:04, Anthony Ferrara (ircmax...@gmail.com) wrote:
Joost,
First off, let me say welcome and thanks for the contribution!
I have a couple of questions around the intended proposal.
1. How do you plan on handling the case where there are multiple catch
blocks?
try {
code();
} catch {
doSomething();
} catch {
doSomethingElse();
}
As mentioned as latest sentence in the Proposal chapter, an anonymous
catch can only be used as the latest catch, and there can only be one of
them. This is also how my current implementation works.
2. You mention as a benefit Better possibilities for static analysis
tools. Can you elaborate on this? I don't see how this sort of a change
would have any effect (as catch would be the same as the existing `catch
(\Exception $e)`)...
It's mostly for finding unused variables. I suppose that static analysers
currently ignore unused exception variables, but they don't have to when
this is accepted and can properly indicate unused exception variables.
3. What benefit short of not having to type `(\Exception $e)` would this
have? Populating the symbol table is extremely cheap at this stage, because
the variable is already compiled in (so no hash table lookup or anything).
Performance wise it's indeed very minor and doesn't really matter. It's
more that you're adding code indicating that only a specific exception is
used, while that may not really be the case.
Consider Java people --Java has Throwable as the superclass of Exception--
they may not know that in PHP 'Exception' is the least-specific type and
therefore used as catch-all.
As for leaving of the variable, the type of an exception mostly tells
enough about what happened (well, it should), so you don't have to inspect
the exception's error code/message and thus don't need the exception object
at all.
Additionally, I would recommend changing the version target to 5.NEXT
(which would be 5.6 in practice).
Done!
As far as my personal feelings, I'd like to get some other commentary
first.
Thanks again!!!
Anthony
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I'm just going to weigh-in here with my two cents.
When I look at the facts objectively I don't see a reason to turn down this
proposal, but I also don't see much of a reason to accept it. My only fear
is that people will abuse anonymous catch blocks in situations where it
would have been better to just properly handle the Exception.
For example, if you're doing this in your code you're probably writing some
pretty bad code that's tough to debug...
try
{
$this-connectToServer();
} catch {
$this-retry(3);
}
Why are we throwing Exceptions if we only want to retry the connection in
the event that it failed? That would be more likely better handled by the
callee where the connection can be retired up to a timeout or number of
re-attempts until it fails permanently and then throws an Exception.
Exceptions should be like broken promises. If the promise the method or
function makes can't be kept it should throw an Exception to notify the
caller and the caller should decide how to proceed from there. If the
caller doesn't care that the promise could not be kept they probably have
very special circumstances to consider. So I can live with catch(Exception
$e) { /* ignore $e */ }, but that's my only objection. It's one purely from
a stand-point of promoting better code.
I understand a lot of other languages may allow this, but then again a lot
of other languages give you more room to shoot yourself in the foot than
PHP does.
I'm pretty neutral about this feature overall.
