From: Daniel Shahaf <danielsh@apache.org>
To: zsh-workers@zsh.org
Subject: [PATCH 1/3] zshexpn: Describe parameter elision and add some introductory prose
Date: Sun, 12 Jan 2020 22:29:26 +0000 [thread overview]
Message-ID: <20200112222928.25546-1-danielsh@apache.org> (raw)
---
The three patches in this series are independent of each other.
Cheers,
Daniel
Doc/Zsh/expn.yo | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
index 9451fa605..c129b4228 100644
--- a/Doc/Zsh/expn.yo
+++ b/Doc/Zsh/expn.yo
@@ -582,7 +582,25 @@ and subscript notation to access individual array elements.
Note in particular the fact that words of unquoted parameters are not
automatically split on whitespace unless the option tt(SH_WORD_SPLIT) is
set; see references to this option below for more details. This is an
-important difference from other shells.
+important difference from other shells. However, as in other shells,
+null words are elided from unquoted parameters' expansions.
+
+With default options, after the assignments:
+
+example(array=("first word" "" "third word")
+scalar="only word")
+
+then tt($array) substitutes two words, `tt(first word)' and `tt(third
+word)', and tt($scalar) substitutes a single word `tt(only word)'. Note
+that second element of tt(array) was elided. Scalar parameters can
+be elided too if their value is null (empty). To avoid elision, use quoting as
+follows: tt("$scalar") for scalars and tt("${array[@]}") or tt("${(@)array}")
+for arrays. (The last two forms are equivalent.)
+
+Parameter expansions can involve em(flags), as in `tt(${(@kv)aliases})',
+and other operators, such as `tt(${PREFIX:-"/usr/local"})'. Parameter
+expansions can also be nested. These topics will be introduced below.
+The full rules are complicated and are noted at the end.
In the expansions discussed below that require a pattern, the form of
the pattern is the same as that used for filename generation;
@@ -594,17 +612,8 @@ noderef(Modifiers) in noderef(History Expansion) can be
applied: for example, tt(${i:s/foo/bar/}) performs string
substitution on the expansion of parameter tt($i).
-In the following descriptions, `word' refers to a single word
+In the following descriptions, `var(word)' refers to a single word
substituted on the command line, not necessarily a space delimited word.
-With default options, after the assignments:
-
-example(array=("first word" "second word")
-scalar="only word")
-
-then tt($array) substitutes two words, `tt(first word)' and `tt(second
-word)', and tt($scalar) substitutes a single word `tt(only word)'. This
-may be modified by explicit or implicit word-splitting, however. The
-full rules are complicated and are noted at the end.
startitem()
item(tt(${)var(name)tt(}))(
next reply other threads:[~2020-01-12 22:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-12 22:29 Daniel Shahaf [this message]
2020-01-12 22:29 ` [PATCH 2/3] _git: Complete bisect/new as well as bisect/bad Daniel Shahaf
2020-01-12 22:29 ` [PATCH 3/3] _git: Complete --contains after -r (--remotes) Daniel Shahaf
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