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27976: more parameter substitution order description

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Peter Stephenson 2010-05-27 18:52:30 +00:00
parent 17b7471fbc
commit 43ee0cd4fd
2 changed files with 46 additions and 9 deletions
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ChangeLog
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@ -1,3 +1,8 @@
2010-05-27 Peter Stephenson <p.w.stephenson@ntlworld.com>
* 27976: Doc/Zsh/expn.yo: add yet more to the my-brain-hurts
description of how parameter expansion is ordered.
2010-05-27 Frank Terbeck <ft@bewatermyfriend.org>
* Seth House: 27971: Functions/VCS_Info/Backends/VCS_INFO_get_data_hg:
@ -13159,5 +13164,5 @@
*****************************************************
* This is used by the shell to define $ZSH_PATCHLEVEL
* $Revision: 1.4982 $
* $Revision: 1.4983 $
*****************************************************

48
Doc/Zsh/expn.yo
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@ -1172,7 +1172,15 @@ Any modifiers, as specified by a trailing `tt(#)', `tt(%)', `tt(/)'
noderef(Modifiers) in noderef(History Expansion)), are applied to the words
of the value at this level.
)
item(tt(8.) em(Forced Joining))(
item(tt(8.) em(Character evaluation))(
Any tt((#)) flag is applied, evaluating the result so far numerically
as a character.
)
item(tt(9.) em(Length))(
Any initial tt(#) modifier, i.e. in the form tt(${#)var(var)tt(}), is
used to evaluate the length of the expression so far.
)
item(tt(10.) em(Forced Joining))(
If the `tt((j))' flag is present, or no `tt((j))' flag is present but
the string is to be split as given by rules tt(8.) or tt(9.), and joining
did not take place at step tt(4.), any words in the value are joined
@ -1180,36 +1188,51 @@ together using the given string or the first character of tt($IFS) if none.
Note that the `tt((F))' flag implicitly supplies a string for joining in this
manner.
)
item(tt(9.) em(Forced Splitting))(
item(tt(11.) em(Case modification))(
Any case modification from one of the flags tt((L)), tt((U)) or tt((C))
is applied.
)
item(tt(12.) em(Prompt evaluation))(
Any prompt-style formatting from the tt((%)) family of flags is applied.
)
item(tt(13.) em(Quote application))(
Any quoting or unquoting using tt((q)) and tt((Q)) and related flags
is applied.
)
item(tt(14.) em(Visibility enhancment))(
Any modifications to make characters visible using the tt((V)) flag
are applied.
)
item(tt(15.) em(Forced Splitting))(
If one of the `tt((s))', `tt((f))' or `tt((z))' flags are present, or the `tt(=)'
specifier was present (e.g. tt(${=)var(var)tt(})), the word is split on
occurrences of the specified string, or (for tt(=) with neither of the two
flags present) any of the characters in tt($IFS).
)
item(tt(10.) em(Shell Word Splitting))(
item(tt(16.) em(Shell Word Splitting))(
If no `tt((s))', `tt((f))' or `tt(=)' was given, but the word is not
quoted and the option tt(SH_WORD_SPLIT) is set, the word is split on
occurrences of any of the characters in tt($IFS). Note this step, too,
takes place at all levels of a nested substitution.
)
item(tt(11.) em(Uniqueness))(
item(tt(17.) em(Uniqueness))(
If the result is an array and the `tt((u))' flag was present, duplicate
elements are removed from the array.
)
item(tt(12.) em(Ordering))(
item(tt(18.) em(Ordering))(
If the result is still an array and one of the `tt((o))' or `tt((O))' flags
was present, the array is reordered.
)
item(tt(13.) em(Re-Evaluation))(
item(tt(19.) em(Re-Evaluation))(
Any `tt((e))' flag is applied to the value, forcing it to be re-examined
for new parameter substitutions, but also for command and arithmetic
substitutions.
)
item(tt(14.) em(Padding))(
item(tt(20.) em(Padding))(
Any padding of the value by the `tt(LPAR()l.)var(fill)tt(.RPAR())' or
`tt(LPAR()r.)var(fill)tt(.RPAR())' flags is applied.
)
item(tt(15.) em(Semantic Joining))(
item(tt(21.) em(Semantic Joining))(
In contexts where expansion semantics requires a single word to
result, all words are rejoined with the first character of tt(IFS)
between. So in `tt(${LPAR()P)tt(RPAR()${LPAR()f)tt(RPAR()lines}})'
@ -1218,6 +1241,15 @@ joined again before the tt(P) flag can be applied.
If a single word is not required, this rule is skipped.
)
item(tt(22.) em(Empty argument removal))(
If the substitution does not appear in double quotes, any resulting
zero-length argument, whether from a scalar or an element of an array,
is elided from the list of arguments inserted into the command line.
Strictly speaking, the removal happens later as the same happens with
other forms of substitution; the point to note here is simply that
it occurs after any of the above parameter operations.
)
enditem()
subsect(Examples)