From: fche@redhat.com (Frank Ch. Eigler)
To: Craig Ringer <craig@2ndquadrant.com>
Cc: systemtap@sourceware.org
Subject: Re: Safe-dereference operator?
Date: Tue, 18 Aug 2020 19:04:19 -0400 [thread overview]
Message-ID: <87lfibv9n0.fsf@redhat.com> (raw)
In-Reply-To: <CAMsr+YG7sYTHJ_b2ped=AK7wCJygFkqGm8xBfEXeFnGyiL90jQ@mail.gmail.com> (Craig Ringer's message of "Fri, 17 Jul 2020 11:22:32 +0800")
craig wrote:
> TL;DR: Proposal to add a safe-dereference pseudo-operator like Groovy's ?.
> to the language to simplify chasing pointer chains.
> ?. is basically an abbreviated ternary without the multiple-evaluation
> hazard:
> a ?. b ?. c
This sounds like something that can be done via a macro
(tapset/SOMETHING.stpm) with a functional syntax, if you
can accept the multiple-evaluation problem:
@define pointer_chase_1(a,b) %( @a ? @a->@b : 0 %)
@define pointer_chase_2(a,b,c) %( @a ? (@a->@b ? @a->@b->@c : 0) : 0 %)
If you can't ... can you explain why? Must those index
fields depend on state-modifying calculations?
- FChE
prev parent reply other threads:[~2020-08-18 23:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 3:22 Craig Ringer
2020-08-18 23:04 ` Frank Ch. Eigler [this message]
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