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From: Simon Marchi <simon.marchi@polymtl.ca>
To: Andrew Burgess <aburgess@redhat.com>,
	"Metzger, Markus T" <markus.t.metzger@intel.com>
Cc: "vries@gcc.gnu.org" <vries@gcc.gnu.org>,
	"gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Subject: Re: [PATCH v3] gdb: c++ify btrace_target_info
Date: Mon, 11 Sep 2023 11:27:00 -0400	[thread overview]
Message-ID: <5b40b596-a3f0-42df-9dd9-20af5d0f831b@polymtl.ca> (raw)
In-Reply-To: <87tts0kcs8.fsf@redhat.com>

On 9/11/23 10:25, Andrew Burgess wrote:
> "Metzger, Markus T" <markus.t.metzger@intel.com> writes:
> 
>> Hello Andrew,
>>
>>>>>> -  gdb::unique_xmalloc_ptr<btrace_target_info> tinfo
>>>>>> -    (XCNEW (btrace_target_info));
>>>>>> -  tinfo->ptid = ptid;
>>>>>> +  std::unique_ptr<linux_btrace_target_info> tinfo
>>>>>> +    { new linux_btrace_target_info { ptid } };
>>>>>
>>>>> We recently added a gdb::make_unique function, it would make sense to
>>>>> you use it here (it will eventually become std::make_unique once we
>>>>> migrate to C++ 14).
>>>>>
>>>>> So this could be written as:
>>>>>
>>>>>  auto tinfo = gdb::make_unique<linux_btrace_target_info> (ptid);
>>>>
>>>> I'm not a fan of 'auto'.  So this becomes
>>>>
>>>>   std::unique_ptr<linux_btrace_target_info> tinfo
>>>>     { gdb::make_unique<linux_btrace_target_info> (ptid) };
>>>
>>> This really doesn't feel like an improvement.
>>>
>>> I also try to avoid excessive use of auto, so I dislike things like:
>>>
>>>  auto var = some_function (....);
>>>
>>> because there's no hint what the type of var actually is (without
>>> looking at `some_function`).  But in the case of:
>>>
>>>  auto var = gdb::make_unique<type> (...);
>>>
>>> The type of var is right there on the line, so duplicating the type
>>> information is just noise.  For me this is a perfect use of auto.
>>
>> A related question is whether
>>
>>     auto ptr { gdb::make_unique<type> (...) }
>>
>> is really any better than
>>
>>     std::unique_ptr<type> ptr { new type (...) }
> 
> Well std::make_unique<> exists, so I think like it or not, that's the
> preferred C++ approach.
> 
> I thought (though I don't claim to be an expert) that, in general,
> direct calls to 'new' were to be avoided in C++ code.
> 
> Thanks,
> Andrew

I agree with Andrew for his comments on both topics (the non-excessive
use of auto and make_unique).

Simon

      reply	other threads:[~2023-09-11 15:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-08 10:53 Markus Metzger
2023-09-08 14:31 ` Simon Marchi
2023-09-11  6:18   ` Metzger, Markus T
2023-09-11  9:17     ` Andrew Burgess
2023-09-11  9:53       ` Metzger, Markus T
2023-09-11 14:25         ` Andrew Burgess
2023-09-11 15:27           ` Simon Marchi [this message]

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