diff options
Diffstat (limited to 'doc/Tcl.n')
| -rw-r--r-- | doc/Tcl.n | 44 |
1 files changed, 35 insertions, 9 deletions
@@ -48,7 +48,6 @@ 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. -.VS 8.5 br .IP "[5] \fBArgument expansion.\fR" If a word starts with the string .QW {*} @@ -60,10 +59,9 @@ variable substitutions; backslash substitutions are performed as is normal for a list and individual internal words may be surrounded by either braces or double-quote characters), and its words are added to the command being substituted. For instance, -.QW "cmd a {*}{b [c]} d {*}{$e f \N'34'g h\N'34'}" +.QW "cmd a {*}{b [c]} d {*}{$e f {g h}}" is equivalent to -.QW "cmd a b {[c]} d {$e} f \N'34'g h\N'34'" . -.VE 8.5 +.QW "cmd a b {[c]} d {$e} f {g h}" . .IP "[6] \fBBraces.\fR" If the first character of a word is an open brace .PQ { @@ -106,24 +104,44 @@ Variable substitution may take any of the following forms: .RS .TP 15 \fB$\fIname\fR +. \fIName\fR is the name of a scalar variable; the name is a sequence of one or more characters that are a letter, digit, underscore, or namespace separators (two or more colons). +Letters and digits are \fIonly\fR the standard ASCII ones (\fB0\fR\-\fB9\fR, +\fBA\fR\-\fBZ\fR and \fBa\fR\-\fBz\fR). .TP 15 \fB$\fIname\fB(\fIindex\fB)\fR +. \fIName\fR gives the name of an array variable and \fIindex\fR gives the name of an element within that array. \fIName\fR must contain only letters, digits, underscores, and namespace separators, and may be an empty string. +Letters and digits are \fIonly\fR the standard ASCII ones (\fB0\fR\-\fB9\fR, +\fBA\fR\-\fBZ\fR and \fBa\fR\-\fBz\fR). Command substitutions, variable substitutions, and backslash substitutions are performed on the characters of \fIindex\fR. .TP 15 \fB${\fIname\fB}\fR -\fIName\fR is the name of a scalar variable. It may contain any -characters whatsoever except for close braces. -.LP +. +\fIName\fR is the name of a scalar variable or array element. It may contain +any characters whatsoever except for close braces. It indicates an array +element if \fIname\fR is in the form +.QW \fIarrayName\fB(\fIindex\fB)\fR +where \fIarrayName\fR does not contain any open parenthesis characters, +.QW \fB(\fR , +or close brace characters, +.QW \fB}\fR , +and \fIindex\fR can be any sequence of characters except for close brace +characters. No further +substitutions are performed during the parsing of \fIname\fR. +.PP There may be any number of variable substitutions in a single word. Variable substitution is not performed on words enclosed in braces. +.PP +Note that variables may contain character sequences other than those listed +above, but in that case other mechanisms must be used to access them (e.g., +via the \fBset\fR command's single-argument form). .RE .IP "[9] \fBBackslash substitution.\fR" If a backslash @@ -192,7 +210,7 @@ be 0. The hexadecimal digits \fIhhhh\fR (one, two, three, or four of them) give a sixteen-bit hexadecimal value for the Unicode character that will be inserted. -.LP +.PP Backslash substitution is not performed on words enclosed in braces, except for backslash-newline as described above. .RE @@ -217,13 +235,15 @@ no substitutions are performed before making the recursive call and no additional substitutions are performed on the result of the nested script. .RS -.LP +.PP Substitutions take place from left to right, and each substitution is evaluated completely before attempting to evaluate the next. Thus, a sequence like +.PP .CS set y [set x 0][incr x][incr x] .CE +.PP will always set the variable \fIy\fR to the value, \fI012\fR. .RE .IP "[12] \fBSubstitution and word boundaries.\fR" @@ -232,3 +252,9 @@ 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. +.SH KEYWORDS +backslash, command, comment, script, substitution, variable +'\" Local Variables: +'\" mode: nroff +'\" fill-column: 78 +'\" End: |