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Re: Subtle bugs in interval code.

From: Johan Bockgård
Subject: Re: Subtle bugs in interval code.
Date: Fri, 23 Mar 2007 15:59:39 +0100
User-agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.93 (gnu/linux)

address@hidden (Kim F. Storm) writes:

> Note that we cannot just use plist-get instead of memq, as we then
> cannot differentiate between "property is on list with nil value"
> and "property is not on list".

    plist-member is a built-in function in `src/fns.c'.
    (plist-member plist prop)

    Return non-nil if plist has the property prop.
    plist is a property list, which is a list of the form
    (PROP1 VALUE1 PROP2 VALUE2 ...).  prop is a symbol.
    Unlike `plist-get', this allows you to distinguish between a missing
    property and a property with the value nil.
    The value is actually the tail of plist whose car is prop.

Johan Bockgård

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