linux-kernel - Re: [RFC v2] scripts: kernel-doc: reduce repeated regex expressions into variables

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Date:   Tue, 27 Apr 2021 17:56:33 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Jonathan Corbet <corbet@....net>
Cc:     Aditya Srivastava <yashsri421@...il.com>, lukas.bulwahn@...il.com,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC v2] scripts: kernel-doc: reduce repeated regex expressions
 into variables

On Tue, Apr 27, 2021 at 09:55:35AM -0600, Jonathan Corbet wrote:
> The use of the variables here doesn't really make those expressions more
> readable.  
> 
> >  	$members =~ s/\s*CRYPTO_MINALIGN_ATTR/ /gos;
> > -	$members =~ s/\s*____cacheline_aligned_in_smp/ /gos;
> > -	$members =~ s/\s*____cacheline_aligned/ /gos;
> > +	$members =~ s/\s*$cacheline_aligned_in_smp/ /gos;
> > +	$members =~ s/\s*$cacheline_aligned/ /gos;
> >  
> > +	my $args = qr{([^,)]+)};
> >  	# replace DECLARE_BITMAP
> >  	$members =~ s/__ETHTOOL_DECLARE_LINK_MODE_MASK\s*\(([^\)]+)\)/DECLARE_BITMAP($1, __ETHTOOL_LINK_MODE_MASK_NBITS)/gos;
> > -	$members =~ s/DECLARE_BITMAP\s*\(([^,)]+),\s*([^,)]+)\)/unsigned long $1\[BITS_TO_LONGS($2)\]/gos;
> > +	$members =~ s/DECLARE_BITMAP\s*\($args,\s*$args\)/unsigned long $1\[BITS_TO_LONGS($2)\]/gos;
> 
> Here too ... this is the kind of stuff that makes me glad that Colorado
> is a legal-weed state, and the new version, while better, doesn't change
> that basic fact.

I'm going to have to disagree with you on this one (I agree with you on all
the others).  I find this much easier to read ...

"DECLARE_BITMAP followed by any amount of whitespace, literal open bracket,
an argument, literal comma, whitespace, another argument, literal close bracket"

Before, I get to "DECLARE_BITMAP followed by any amount of whitespace,
then some line noise".

Obviously I'm less experienced at reading regexes than you are, but this
simplification really does help me.

> I think I'll stop here; hopefully I've gotten my point across.  I really
> like where this work is heading; focusing just a bit more on pulling the
> regexes together and making the whole thing more readable would be
> wonderful.

Amen.