From f5a39157bddc11662b93e06a9845c3d8a8dd7fa3 Mon Sep 17 00:00:00 2001 From: Jeremy Harris Date: Tue, 26 Jul 2022 19:05:33 +0100 Subject: [PATCH] Docs: tweak list-syntax description --- doc/doc-docbook/spec.xfpt | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 82f6ac0e4..ed0036e0c 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -6559,15 +6559,17 @@ cause parts of the string to be replaced by data that is obtained from the lookup. Lookups of this type are conditional expansion items. Different results can be defined for the cases of lookup success and failure. See chapter &<>&, where string expansions are described in detail. -The key for the lookup is &*specified*& as part of the string expansion. +The key for the lookup is &*specified*& as part of the string to be expanded. .next Lists of domains, hosts, and email addresses can contain lookup requests as a way of avoiding excessively long linear lists. In this case, the data that is returned by the lookup is often (but not always) discarded; whether the lookup succeeds or fails is what really counts. These kinds of list are described in chapter &<>&. -The key for the lookup is &*implicit*&, -given by the context in which the list is expanded. +Depending on the lookup type (see below) +the key for the lookup may need to be &*specified*& as above +or may be &*implicit*&, +given by the context in which the list is being checked. .endlist String expansions, lists, and lookups interact with each other in such a way @@ -6586,6 +6588,7 @@ Be careful to distinguish between the following two examples: domains = ${lookup{$sender_host_address}lsearch{/some/file}} domains = lsearch;/some/file .endd +.ilist The first uses a string expansion, the result of which must be a domain list. The key for an expansion-style lookup must be given explicitly. No strings have been specified for a successful or a failing lookup; the @@ -6602,6 +6605,7 @@ possibly other types of item that are allowed in domain lists). .cindex "de-tainting" "using a lookup expansion"" The result of the expansion is not tainted. +.next In the second example, the lookup is a single item in a domain list. It causes Exim to use a lookup to see if the domain that is being processed can be found in the file. @@ -6615,7 +6619,8 @@ matches the list item. The key for a list-style lookup is implicit, from the lookup context, if the lookup is a single-key type (see below). -For query-style lookup types the key must be given explicitly. +For query-style lookup types the query must be given explicitly. +.endlist It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: @@ -6660,6 +6665,7 @@ If this is given and the lookup (either underlying implementation or cached value) returns data, the result is replaced with a non-tainted version of the lookup key. + .next .cindex "query-style lookup" "definition of" The &'query-style'& type accepts a generalized database query. No particular -- 2.30.2