Re: Parsing config files in a directory

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Parsing config files in a directory
Date: 2009-10-28 19:08:48
Message-ID: 4AE896C0.40706@agliodbs.com
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Kevin,

> Perhaps the ease of writing something like that with sed or perl has
> caused me to underestimate the effort required in C. I am curious
> whether you actually mean that, or said it for rhetorical effect.

I actually mean that. It *looks* easy in perl, and in fact *is* easy
for *your* postgresql.conf which you control. But writing a parser for
every postgresql.conf which exists in the world, no matter how someone
has hacked it up creatively? No matter how they've handled upgrades?
For every version of PostgreSQL? That requires writing a full parser
with grammar and near-turing capabilities.

> Well, I wouldn't vote against it since it seems to do me no harm; I
> was just confused at the repeated assertion that update-in-place was
> such a hard problem.

It's the basic and unsolvable issue of how do you have a file which is
both perfectly human-readable-and-editable *and* perfectly
machine-readable-and-editable at the same time.

--Josh Berkus

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