From: Michael Heerdegen <michael_heerdegen@web.de>
To: "Mattias Engdegård" <mattiase@acm.org>
Cc: 50136@debbugs.gnu.org, monnier@iro.umontreal.ca
Subject: bug#50136: 28.0.50; A problem with rx-let expansion
Date: Fri, 20 Aug 2021 19:21:20 +0200 [thread overview]
Message-ID: <87y28whw1b.fsf@web.de> (raw)
In-Reply-To: <A0D3A614-BCC2-43EB-BB99-E9B63C4CD8EB@acm.org> ("Mattias Engdegård"'s message of "Fri, 20 Aug 2021 17:23:58 +0200")
Mattias Engdegård <mattiase@acm.org> writes:
> > AFAIU, the current approach doesn't allow to extend this with an
> > optional CHARS argument to specify with chars are allowed "in between"
> > (instead of "any"). The "&optional" keyword makes it barf.
>
> That's right. What would be the preferred semantics? For example, what
> value would you expect an absent optional parameter to take?
I guess it's not very useful for the current mechanism. With a
macro-like thing, the expansion would just not use the value if it's nil. The
expander would check whether the argument was provided.
> Actually it's the rx `eval` form that you are looking for if you want
> arbitrary compile-time computation. `regexp` and `literal` are
> explicitly made for run-time expressions.
Yes, I think you are right.
Michael.
next prev parent reply other threads:[~2021-08-20 17:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 13:59 bug#50136: 28.0.50; A problem with rx-let expansion Michael Heerdegen
2021-08-20 14:50 ` Michael Heerdegen
2021-08-20 15:23 ` Mattias Engdegård
2021-08-20 17:21 ` Michael Heerdegen [this message]
2021-08-20 18:45 ` Mattias Engdegård
2021-08-21 11:45 ` Michael Heerdegen
2021-08-21 13:02 ` Mattias Engdegård
2021-08-23 10:45 ` Michael Heerdegen
2021-08-23 12:38 ` Mattias Engdegård
2021-08-23 15:20 ` Mattias Engdegård
2021-08-23 16:59 ` Michael Heerdegen
2021-08-23 18:05 ` Mattias Engdegård
2021-08-21 3:21 ` Richard Stallman
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