diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/Zsh/expn.yo | 72 |
1 files changed, 39 insertions, 33 deletions
diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo index 6f08d7d47..123722e0f 100644 --- a/Doc/Zsh/expn.yo +++ b/Doc/Zsh/expn.yo @@ -1399,17 +1399,18 @@ substitution then applies the modifier tt(:h) and takes the directory part of the path.) ) item(tt(2.) em(Internal parameter flags))( -Any parameter flags set by one of the tt(typeset) family of commands, -in particular the tt(L), tt(R), tt(Z), tt(u) and tt(l) flags for padding -and capitalization, are applied directly to the parameter value. -Note these flags are options to the command, e.g. `tt(typeset -Z)'; -they are not the same as the flags used within parameter substitutions. - -At the outermost level of substitution, the `tt((P))' flag ignores these -transformations and uses the unmodified value of the parameter as the name -to be replaced. This is usually the desired behavior because padding may -make the value syntactically illegal as a parameter name, but if -capitalization changes are desired, use the tt(${${(P)foo}}) form. +Any parameter flags set by one of the tt(typeset) family of commands, in +particular the tt(-L), tt(-R), tt(-Z), tt(-u) and tt(-l) options for +padding and capitalization, are applied directly to the parameter value. +Note these flags are options to the command, e.g. `tt(typeset -Z)'; they +are not the same as the flags used within parameter substitutions. + +At the outermost level of substitution, the `tt((P))' flag (rule tt(4.)) +ignores these transformations and uses the unmodified value of the +parameter as the name to be replaced. This is usually the desired +behavior because padding may make the value syntactically illegal as a +parameter name, but if capitalization changes are desired, use the +tt(${${(P)foo}}) form (rule tt(25.)). ) item(tt(3.) em(Parameter subscripting))( If the value is a raw parameter reference with a subscript, such as @@ -1420,21 +1421,25 @@ subscript. Thus if tt(var) is an array, tt(${var[1][2]}) is the second character of the first word, but tt(${var[2,4][2]}) is the entire third word (the second word of the range of words two through four of the original array). Any number of subscripts may appear. Flags such as -tt((k)) and tt((v)) which alter the result of subscripting are applied. +`tt((k))' and `tt((v))' which alter the result of subscripting are applied. ) item(tt(4.) em(Parameter name replacement))( -At the outermost level of nesting only, the effect of any tt((P)) flag, -which treats the value so far as a parameter name and replaces it with the -corresponding value, is applied. This replacement occurs later if the -tt((P)) flag appears in a nested substitution. +At the outermost level of nesting only, the `tt((P))' flag is applied. This +treats the value so far as a parameter name (which may include a subscript +expression) and replaces that with the corresponding value. This +replacement occurs later if the `tt((P))' flag appears in a nested +substitution. + +If the value so far names a parameter that has internal flags (rule tt(2.)), +those internal flags are applied to the new value after replacement. ) item(tt(5.) em(Double-quoted joining))( If the value after this process is an array, and the substitution -appears in double quotes, and neither an tt((@)) flag nor a tt(#) +appears in double quotes, and neither an `tt((@))' flag nor a `tt(#)' length operator is present at the current level, then words of the value are joined with the first character of the parameter tt($IFS), by default a space, between each word (single word arrays are not -modified). If the tt((j)) flag is present, that is used for joining +modified). If the `tt((j))' flag is present, that is used for joining instead of tt($IFS). ) item(tt(6.) em(Nested subscripting))( @@ -1448,22 +1453,22 @@ returns a scalar because of the quotes). ) item(tt(7.) em(Modifiers))( Any modifiers, as specified by a trailing `tt(#)', `tt(%)', `tt(/)' -(possibly doubled) or by a set of modifiers of the form tt(:...) (see +(possibly doubled) or by a set of modifiers of the form `tt(:...)' (see noderef(Modifiers) in noderef(History Expansion)), are applied to the words of the value at this level. ) item(tt(8.) em(Character evaluation))( -Any tt((#)) flag is applied, evaluating the result so far numerically +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(${#)var(var)tt(}), is +Any initial `tt(#)' modifier, i.e. in the form tt(${#)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 rule tt(11.), and joining -did not take place at step tt(5.), any words in the value are joined +did not take place at rule tt(5.), any words in the value are joined together using the given string or the first character of tt($IFS) if none. Note that the `tt((F))' flag implicitly supplies a string for joining in this manner. @@ -1480,22 +1485,22 @@ occurrences of any of the characters in tt($IFS). Note this step, too, takes place at all levels of a nested substitution. ) item(tt(12.) em(Case modification))( -Any case modification from one of the flags tt((L)), tt((U)) or tt((C)) +Any case modification from one of the flags `tt((L))', `tt((U))' or `tt((C))' is applied. ) item(tt(13.) em(Escape sequence replacement))( -First any replacements from the tt((g)) flag are performed, then any -prompt-style formatting from the tt((%)) family of flags is applied. +First any replacements from the `tt((g))' flag are performed, then any +prompt-style formatting from the `tt((%))' family of flags is applied. ) item(tt(14.) em(Quote application))( -Any quoting or unquoting using tt((q)) and tt((Q)) and related flags +Any quoting or unquoting using `tt((q))' and `tt((Q))' and related flags is applied. ) item(tt(15.) em(Directory naming))( -Any directory name substitution using tt((D)) flag is applied. +Any directory name substitution using `tt((D))' flag is applied. ) item(tt(16.) em(Visibility enhancement))( -Any modifications to make characters visible using the tt((V)) flag +Any modifications to make characters visible using the `tt((V))' flag are applied. ) item(tt(17.) em(Lexical word splitting))( @@ -1533,7 +1538,7 @@ 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}})' the value of tt(${lines}) is split at newlines, but then must be -joined again before the tt(P) flag can be applied. +joined again before the `tt((P))' flag can be applied. If a single word is not required, this rule is skipped. ) @@ -1546,10 +1551,11 @@ 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. ) -item(tt(25.) em(Parameter name replacement))( -If the `tt((P))' flag is present and this has not yet been done, the value -so far is looked up as a parameter name. Errors may occur if the value is -neither a valid identifier nor an identifier plus subscript expression. +item(tt(25.) em(Nested parameter name replacement))( +If the `tt((P))' flag is present and rule tt(4.) has not applied, the +value so far is treated as a parameter name (which may include a subscript +expression) and replaced with the corresponding value, with internal flags +(rule tt(2.)) applied to the new value. ) enditem() |