> So why even mention it then?
I think it's because most implementations are not aware of this difference,
but it's important.
It doesn't automatically mean that the interface must reflect the
DependencyNotFoundException.
@throws FooException means "it's your possible issue, take care of it".
@throws DependencyNotFoundException means "My arm can be broken, take care
of it".
@throws ConfigrationDoesNotExistException means "My leg is broken, take
care of it".
> As someone building a framework that uses a container I would very much
care about the distinction between group 2 and group 3
Could you, please, provide us a real use-case when you need to catch
DependencyNotFoundException?
On Friday, November 11, 2016 at 9:19:11 PM UTC+3, Larry Garfield wrote:
>
> I'm not suggesting converting all exceptions that might possibly happen to
> MisconfiguredServiceException. I'm saying there's 3 broad categories:
>
> 1) What you asked for doesn't exist.
> 2) What you asked for is broken.
> 3) Something else happened, WTF? (Eg, a database-backed container has a
> missing DB.)
>
> I agree that group 3 is out of scope. Group 1 is already covered. The
> question is group 2, where "there is something wrong with the container but
> it's not that what you asked for is missing" is, I assert, legitimately in
> scope. As someone building a framework that uses a container I would very
> much care about the distinction between group 2 and group 3. That doesn't
> mean fully exploring all possible details of group 2 and what might break,
> just indicating the separation between groups 2 and 3.
>
> The current text says, in essence, "for group 2, throw anything but the
> same as group 1". So why even mention it then? And no, that's not a
> suggestion to remove yet more things from the spec. :-) (That way lies
> more incompatibility.) I'm saying there should be a clearly defined
> exception for group 1, a clearly defined parent exception for group 2
> (subclasses specific to a given implementation entirely welcome), and group
> 3 is not-our-problem.
>
> --Larry Garfield
>
> On 11/07/2016 12:20 PM, Daniel Plainview wrote:
>
> The major problem with unchecked exceptions is that it is not class
> consumer business.
> What do you say when someone throws SomethingIsBrokenInsideOfMe to you?
> I'd say "hey, take a vacation, fix yourself, you look unhealthy". Is it not
> my business what exactly is broken (leg or arm, whatever, it doesn't help
> to fix my issue). But it is fair enough if library throws YouAreWrong
> exception in my face when I'm screwed up.
>
> When you make a typo in your Container implementation, it could fail with
> something like \TypeError. It is "unhappy-path", isn't it? Is
> it MisconfiguredServiceException? I don't think so. What do you do then?
> You go and fix your implementation. What happens if configuration is
> broken? You go and fix it as well. I don't see much difference here.
>
> MisconfiguredServiceException for me is an illusory solution for
> "unhappy-path". You can't trust it. What does it exactly mean? What if you
> make a syntax typo in your PHP configuration (with arrays, let's say),
> should it raise the MisconfiguredServiceException? Or it should bubble up
> \ParseError? I mean, it is more like ConfigurationIsTotallyScrewedUp rather
> than simple MisconfiguredService. It's vague exception that means
> "something is wrong with *them*". I'd rather catch ALL other
> (non-NotFoundException) exceptions if I want to avoid program crash for
> some reason. I can trust \Exception (or even \Throwable). The meaning is
> simply same: "something is wrong with them" and I don't really care what
> exactly is.
>
> Can you please provide real-life example when you want to catch
> MisconfiguredServiceException (excepting "I want to log it differently",
> because it doesn't look real-life, honestly; and it is too universal answer
> for any kind of exceptions)?
>
> On Monday, November 7, 2016 at 5:27:58 PM UTC+3, Larry Garfield wrote:
>>
>> Container nesting is part of the spec, and a stated goal of the spec, so
>> it's a valid use case to consider.
>>
>> True, there are many different ways that things can break. Consistent
>> and constructive handling of the not-happy path is a critical part of spec
>> development. See also: HTML5, the majority of which is not new stuff but
>> standardizing the many different ways that browsers used to handle badly
>> formed HTML. It's a total mess because the unhappy path was never
>> well-defined, so everyone did it differently, so code broke in a variety of
>> inconsistent ways. My issue is that "throw anything other than X" is not a
>> consistent and constructive handling of the non-happy path.
>>
>> The biggest distinction I would draw would be between "you asked for
>> something that's not there" and "you asked for something that's broken".
>> Those are very different things; one implies I screwed up, the other
>> implies the configurer screwed up. I can see the argument for not
>> specifying a separate exception for every possible way that the requested
>> service is broken (there are many, that's true), but a clear distinction
>> between those two broad categories ("missing" and "broken") seems like a
>> much better baseline.
>>
>> In that case, I would revise my ask to defining two exceptions:
>>
>> * NotFoundException extends ContainerExceptionInterface (thrown if the
>> requested service isn't defined anywhere)
>> * MisconfiguredServiceException extends ContainerExceptionInterface
>> (thrown if the requested service is defined, but for whatever reason can't
>> be instantiated)
>>
>> And implementers are free to subclass the latter if they choose, but must
>> still have that exception flag on them. (I'm flexible on the name, the one
>> I have there is likely not the best name.)
>>
>> --Larry Garfield
>>
>> On 11/05/2016 12:59 PM, Daniel Plainview wrote:
>>
>> > A situation of "if your child container throws exception X, you're
>> required to catch it and turn it into anything that's not X but is still Y"
>> seems needlessly convoluted
>>
>> You did it by introducing "child container", Container contract doesn't
>> have any child containers, this contract is very simple
>> and straightforward. By saying about child containers, you mean that you
>> know how internals of the Container work, you know about "child
>> containers", but you shouldn't care about it when you want to use Container.
>>
>> > but doesn't provide me as a developer sufficient debug information.
>> I'd potentially want to log differently depending on which exception it is,
>> but I can't do that if I have no idea what the second exception is going to
>> be; I just know what it's *not* going to be, which means I'd need a
>> Pokemon-catch if I wanted to log it. That's what I am not comfortable with.
>>
>> I asked you above, what do you think about
>> DependencyArgumentTypeMismatchException, MissingRequiredArgumentException
>> and many other exceptions, what makes them less important than
>> DependencyNotFoundException? They are all about wrong configuration (or
>> similar issues that indicates of internal problems of Container, not user's
>> failure).
>>
>> I mean, you can say that "I'd potentially want to log differenty
>> DependencyArgumentTypeMismatchException and
>> MissingRequiredArgumentException, but I don't know how to catch them".
>> There are millions of reasons why container can be broken, after all, you
>> can't predict them all.
>>
>> DependencyNotFoundException is unchecked, because it is not client's
>> problem, but internal issue of Container itself. Service does exist, but
>> configuration is wrong, client has nothing to do with it, there is no sense
>> to reflect it in the interface.
>>
>> On Saturday, November 5, 2016 at 3:38:06 AM UTC+3, Larry Garfield wrote:
>>>
>>> On 11/04/2016 06:27 AM, David Négrier wrote:
>>>
>>> I'll try an analogy with Java.
>>>
>>> In Java, there is a difference between checked and unchecked exceptions.
>>> Checked exceptions are the exceptions that should be catched by the user.
>>> Unchecked exceptions are the exceptions for which it makes no sense to
>>> catch them. There is no reason to catch an "unchecked exception" because
>>> there is no way the user can provide an interesting alternative behaviour
>>> in the catch statement. So unchecked exception should essentially always
>>> bubble up all the way to the top of the application and trigger an
>>> exception middleware.
>>>
>>> For PSR-11, we deemed that the NotFoundExceptionInterface was a checked
>>> exception (because if the container does not contain the entry you are
>>> looking for, the user can maybe try an alternative behaviour like looking
>>> for an alias or creating a default entry).
>>> We also deemed that the DependencyNotFoundExceptionInterface was an
>>> unchecked exception (because it means the container is poorly configured
>>> and there is little to do about it except display an error message).
>>>
>>> Finally, we think that checked exceptions should be part of a PSR while
>>> unchecked exceptions should be out of any PSR (because there is no need to
>>> standardize an exception if you don't need to catch it).
>>>
>>> Of course, there is no absolute truth here. We could decide that the
>>> NotFoundExceptionInterface should be "unchecked" (because you can always
>>> call "has" before "get" so there is no reason this exception should be
>>> catched). Also, since it boils down to "what valid use case can I have to
>>> catch a DependencyNotFoundExceptionInterface?", we could also find a valid
>>> use case for catching DependencyNotFoundExceptionInterface and decide it
>>> should be part of the PSR. But so far, a quick survey of frameworks out
>>> there has shown that no-one ever catches the "dependency not found
>>> exceptions".
>>>
>>> Also, Larry, you say:
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> *... based on the spec alone (no metadoc, no GitHub threads) the
>>> following would be legal: try { $c1->get('a'); } catch
>>> (NotFoundExceptionInterface $e) { print $e->getMessage(); // prints
>>> "Service 'b' not found" } *
>>> This is not completely true. The spec states that:
>>>
>>>
>>> *A call to get can trigger additional calls to get (to fetch the
>>> dependencies). If one of those dependencies is missing, the
>>> NotFoundExceptionInterface triggered by the inner get call SHOULD NOT
>>> bubble out. Instead, it should be wrapped in an exception implementing the
>>> ContainerExceptionInterface that does not implement the
>>> NotFoundExceptionInterface. *
>>> So your code example is only valid if the container decides not to
>>> follow the recommendation (we used "SHOULD NOT" instead of "MUST NOT" to
>>> cope with existing containers). Of course, we could also strengthen the
>>> wording and write: *If one of those dependencies is missing, the
>>> NotFoundExceptionInterface triggered by the inner get call MUST NOT bubble
>>> out.*
>>> This way, your code sample would be illegal (but it would be harder for
>>> existing containers to implement PSR-11). I have no strong opinion about
>>> the "SHOULD NOT" vs "MUST NOT" idea so far. Your comments are welcome.
>>>
>>> ++
>>> David.
>>>
>>>
>>> See, I would disagree with dependency-not-found being an unchecked
>>> exception. I think that's the fundamental difference. A situation of "if
>>> your child container throws exception X, you're required to catch it and
>>> turn it into anything that's not X but is still Y" seems needlessly
>>> convoluted, but doesn't provide me as a developer sufficient debug
>>> information. I'd potentially want to log differently depending on which
>>> exception it is, but I can't do that if I have no idea what the second
>>> exception is going to be; I just know what it's *not* going to be, which
>>> means I'd need a Pokemon-catch if I wanted to log it. That's what I am not
>>> comfortable with.
>>>
>>> I am generally very skeptical about SHOULD, and favor MUST in nearly all
>>> cases by default. SHOULD should be read as "you're allowed to be
>>> incompatible here", which is a statement a spec should make as rarely as
>>> possible.
>>>
>>> --Larry Garfield
>>>
>>
>
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