From 7482b4b90b376cc1d1d64ef827d9014879f0ef84 Mon Sep 17 00:00:00 2001 From: Klaus Aehlig Date: Tue, 13 Aug 2024 13:13:29 +0200 Subject: expression language: add nub_left Originally, the expression lanuage only contained a function to deduplicate a list, keeping only the right-most occurence. The reason was that this is the order needed for linking: a library providing an open symbol has to come on the command line after the library using that symbol (and hence making it an open symbol). However, by now use cases have emerged that require a topological sorting where definition comes before use; also, when composing the value of PATH from fragments, we usually want to keep the first occurrence in order for it to take precedence. Therefore, also add "nub_left" as built-in function, allowing a more condense (and slightly more efficient) description in rules instead of the revserse-nub_right-reverse pattern. --- doc/concepts/expressions.md | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'doc') diff --git a/doc/concepts/expressions.md b/doc/concepts/expressions.md index c75f00dc..4db7c8cb 100644 --- a/doc/concepts/expressions.md +++ b/doc/concepts/expressions.md @@ -248,6 +248,11 @@ those) argument(s) to obtain the final result. result is the input list, except that for all duplicate values, all but the rightmost occurrence is removed. + - `"nub_list"` The argument has to be a list. It is an error + if that list contains (directly or indirectly) a name. The + result is the input list, except that for all duplicate + values, all but the leftmost occurrence is removed. + - `"basename"` The argument has to be a string. This string is interpreted as a path, and the file name thereof is returned. -- cgit v1.2.3