Subject: Re: POC: converting Lists into arrays
To: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
References: <11587.1550975080@sss.pgh.pa.us>
 <20190731225756.nozn3j6lgwhm6qvq@alap3.anarazel.de>
 <20190731230047.xtbgswuwopmrhd53@alap3.anarazel.de>
 <20190731230403.ytizwaji7gvof7x3@alap3.anarazel.de>
From: Petr Jelinek <petr@2ndquadrant.com>
Message-ID: <c84fc37c-2e27-736f-ce4f-694e6c9c80e8@2ndquadrant.com>
Date: Thu, 1 Aug 2019 01:17:37 +0200
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On 01/08/2019 01:04, Andres Freund wrote:
> Hi,
> 
> On 2019-07-31 16:00:47 -0700, Andres Freund wrote:
>> On 2019-07-31 15:57:56 -0700, Andres Freund wrote:
>>> I also wonder if a foreach version that includes the typical
>>> (Type *) var = (Type *) lfirst(lc);
>>> or
>>> (Type *) var = castNode(Type, lfirst(lc));
>>> or
>>> OpExpr	   *hclause = lfirst_node(OpExpr, lc);
>>>
>>> would make it nicer to use lists.
>>>
>>> foreach_node_in(Type, name, list) could mean something like
>>>
>>> foreach(ListCell *name##_cell, list)
>>> {
>>>      Type* name = lfirst_node(Type, name##_cell);
>>> }
>>
>> s/lfirst/linitial/ of course. Was looking at code that also used
>> lfirst...
> 
> Bullshit, of course.
> 
> /me performs a tactical withdrawal into his brown paper bag.
> 
> 
>> Reminds me that one advantage of macros like the second one would also
>> be to reduce the use of the confusingly named linitial*(), helping newer
>> hackers.
> 
> But that point just had two consecutive embarassing demonstrations...
> 

Yeah, pg_list.h is one file I never close.

-- 
Petr Jelinek
2ndQuadrant - PostgreSQL Solutions for the Enterprise
https://www.2ndQuadrant.com/