diff options
Diffstat (limited to 'doc/Tcl.n')
| -rw-r--r-- | doc/Tcl.n | 30 |
1 files changed, 20 insertions, 10 deletions
@@ -5,7 +5,7 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: Tcl.n,v 1.9 2003/02/01 19:48:23 kennykb Exp $ +'\" RCS: @(#) $Id: Tcl.n,v 1.10 2003/11/14 20:44:43 dgp Exp $ '\" .so man.macros .TH Tcl n "8.1" Tcl "Tcl Built-In Commands" @@ -49,8 +49,17 @@ as ordinary characters and included in the word. Command substitution, variable substitution, and backslash substitution are performed on the characters between the quotes as described below. The double-quotes are not retained as part of the word. -.IP "[5] \fBBraces.\fR" -If the first character of a word is an open brace (``{'') then +.IP "[5] \fBArgument expansion.\fR" +If a word starts with the string ``{expand}'' followed by a +non-whitespace character, then the leading ``{expand}'' is removed +and the rest of the word is parsed and substituted as any other other +word. After substitution, the word is parsed again without +substitutions, and its words are added to the command being +substituted. For instance, ``cmd a {expand}{b c} d {expand}{e f}'' is +equivalent to ``cmd a b c d e f''. +.IP "[6] \fBBraces.\fR" +If the first character of a word is an open brace (``{'') and +rule [5] does not apply, then the word is terminated by the matching close brace (``}''). Braces nest within the word: for each additional open brace there must be an additional close brace (however, @@ -63,7 +72,7 @@ below, nor do semi-colons, newlines, close brackets, or white space receive any special interpretation. The word will consist of exactly the characters between the outer braces, not including the braces themselves. -.IP "[6] \fBCommand substitution.\fR" +.IP "[7] \fBCommand substitution.\fR" If a word contains an open bracket (``['') then Tcl performs \fIcommand substitution\fR. To do this it invokes the Tcl interpreter recursively to process @@ -75,7 +84,7 @@ substituted into the word in place of the brackets and all of the characters between them. There may be any number of command substitutions in a single word. Command substitution is not performed on words enclosed in braces. -.IP "[7] \fBVariable substitution.\fR" +.IP "[8] \fBVariable substitution.\fR" If a word contains a dollar-sign (``$'') then Tcl performs \fIvariable substitution\fR: the dollar-sign and the following characters are replaced in the word by the value of a variable. @@ -102,7 +111,7 @@ characters whatsoever except for close braces. There may be any number of variable substitutions in a single word. Variable substitution is not performed on words enclosed in braces. .RE -.IP "[8] \fBBackslash substitution.\fR" +.IP "[9] \fBBackslash substitution.\fR" If a backslash (``\e'') appears within a word then \fIbackslash substitution\fR occurs. In all cases but those described below the backslash is dropped and @@ -173,14 +182,14 @@ inserted. Backslash substitution is not performed on words enclosed in braces, except for backslash-newline as described above. .RE -.IP "[9] \fBComments.\fR" +.IP "[10] \fBComments.\fR" If a hash character (``#'') appears at a point where Tcl is expecting the first character of the first word of a command, then the hash character and the characters that follow it, up through the next newline, are treated as a comment and ignored. The comment character only has significance when it appears at the beginning of a command. -.IP "[10] \fBOrder of substitution.\fR" +.IP "[11] \fBOrder of substitution.\fR" Each character is processed exactly once by the Tcl interpreter as part of creating the words of a command. For example, if variable substitution occurs then no further @@ -201,8 +210,9 @@ set y [set x 0][incr x][incr x] .CE will always set the variable \fIy\fR to the value, \fI012\fR. .RE -.IP "[11] \fBSubstitution and word boundaries.\fR" -Substitutions do not affect the word boundaries of a command. +.IP "[12] \fBSubstitution and word boundaries.\fR" +Substitutions do not affect the word boundaries of a command, +except for argument expansion as specified in rule [5]. For example, during variable substitution the entire value of the variable becomes part of a single word, even if the variable's value contains spaces. |