[cfe-dev] clang-format behavior for Obj-C methods with block parameters

[Daniel Jasper via cfe-dev]

On Mon, Dec 14, 2015 at 9:43 AM, manuyavuz <yavuz.nuzumlali at gmail.com>
wrote:

> On 13 Dec 2015, at 20:15, Daniel Jasper <djasper at google.com> wrote:
>
>
>
> On Sun, Dec 13, 2015 at 6:53 PM, Yavuz Nuzumlalı <manuyavuz at gmail.com>
> wrote:
>
>> Thanks for the response Daniel,
>>
>> Could you guide me on where can I look inside clang-format implementation
>> to see how clang-format currently handles lambdas in other languages, so
>> that I may try to implement the same functionality for Objective-C case?
>>
>
> Not really, it is all in ContinuationIndenter.cpp. However, this is among
> the most complex code of clang-format and giving you details on how to do
> this probably would take me longer than looking at this myself. If you
> still want to try and take a look, feel free. I am happy to answer any
> specific questions you might have.
>
>
>>
>> Besides that, I have one more question, which is somewhat related to
>> topic.
>>
>> When I try to use clang-format to format the following simple code:
>>
>> - (void)asdf {
>> [UIView animateasdfasdf:0 animations:^{ }];
>> [UIView animations:^{ } done:YES];
>> [UIView animations:^{ } completion:^{ }];
>> [UIView testasdfasdfsd:YES animations:^{ } completion:^{ }];
>> [UIView animations:^{ } tessd:YES completion:^{ }];
>> }
>>
>> Output is the following:
>>
>> - (void)asdf {
>>   [UIView animateasdfasdf:0
>>                animations:^{
>>                }];
>>   [UIView animations:^{
>>   }
>>                 done:YES];
>>   [UIView animations:^{
>>   }
>>       completion:^{
>>       }];
>>   [UIView testasdfasdfsd:YES
>>       animations:^{
>>       }
>>       completion:^{
>>       }];
>>   [UIView animations:^{
>>   }
>>       tessd:YES
>>       completion:^{
>>       }];
>> }
>>
>> I think clang-format somehow decides to not use colon alignment but align
>> using `ContinuationIndentWidth` where there are more than one block
>> parameters.
>> Is this an intended behavior? Seems like a bug to me.
>>
>
> It is intentional. Column alignment with more than one internal block
> doesn't really work. And this is also explicitly written in Google's style
> guide: https://google.github.io/styleguide/objcguide.xml#Blocks
>
> Independent of that some of you examples look like there are still other
> bugs in there.
>
> I carefully read the google style guide, and behavior about multiple
> inline blocks seems reasonable now.
> However, I still feel it's not fully consistent because of the third
> method call example above.
> I think that case should have something like the following format in order
> to be consistent across the code:
>
> [UIView
>     animations:^{
>     }
>     completion:^{
>     }];
>

As I mentioned in my previous email, there are cases in your example that
look buggy to me. I was just stating that in general, this is intended.

Also there is another case in which formatting messes completely:
>
>   [UIView animateWithDuration:123 delay:123 usingSpringWithDamping:123
> initialSpringVelocity:123 options:123 animations:^{ } completion:^(BOOL
> finished){ }];
>
> becomes this:
>
>   [UIView animateWithDuration:123
>       delay:123
>       usingSpringWithDamping:123
>       initialSpringVelocity:123
>       options:123
>       animations:^{
>       }
>       completion:^(BOOL finished){
>       }];
>
> Is this (cancelling colon alignment also for non-block parameters ) also
> intentional?
>

It is intended and I think it makes sense. However, I have never worked on
ObjC code, so my understanding of the pros and cons is *very* limited.


> If so, I understand that clang-format will apply standard
> `ContinuationIndentWidth` value whenever a method call includes more than
> one inline blocks.
>
> I question this scenario too much because the above code is a frequent
> code block to animate views on screen, and having a consistent behavior is
> important in order to use clang-format’s automatic formatting without any
> hesitancy
>

Sure, I understand. But as I mentioned above, I might actually not be the
best person to ask. As the main author of clang-format, I try to support
ObjC on a best-effort basis, without understanding much of it. There is
also limited time I can spend on this at least in the foreseeable future.

Cheers
Daniel


>
> PS : I'm using the default LLVM configuration for the above case.
>>
>> On 13 Dec 2015, at 16:42, Daniel Jasper <djasper at google.com> wrote:
>>
>> Nope, this behavior isn't currently implemented. I agree that it might
>> make sense, as it is similar to how clang-format treats lambdas at the end
>> of several other parameters.
>>
>> On Fri, Dec 11, 2015 at 4:08 PM, Yavuz Nuzumlalı <cfe-dev at lists.llvm.org
>> > wrote:
>> Hi everyone,
>>
>> I'm experiencing a problem with clang-format for my code.
>>
>> I'm using ColumnLimit as 120. When I write some code like this:
>>
>> [self testMethod:15 withBlock:^{
>> NSLog(@"asdfasdf");
>> NSLog(@"asdfasdf");
>> NSLog(@"asdfasdf");
>> NSLog(@"asdfasdf");
>> }];
>>
>> This code would be converted to this by clang-format:
>>
>> [self testMethod:15
>>        withBlock:^{
>>        NSLog(@"asdfasdf");
>>        NSLog(@"asdfasdf");
>>        NSLog(@"asdfasdf");
>>        NSLog(@"asdfasdf");
>>    }];
>>
>> That seems wrong to me because the method call before block variable
>> actually fits in width of 120. I guess this is because clang-format behaves
>> above code as a single method call and assumes it as one line. But I really
>> want to not split the method like this because it feels weird.
>>
>> Is there a way to accomplish this with current system?
>>
>> I put my configuration file as an attachment.
>>
>> Best
>>
>>
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>>
>>
>>
>
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