1library(n) Tcl Built-In Commands library(n)
2______________________________________________________________________________
6
8 auto_execok, auto_import, auto_load, auto_mkindex, auto_qualify,
9 auto_reset, tcl_findLibrary, parray, tcl_endOfWord,
10 tcl_startOfNextWord, tcl_startOfPreviousWord, tcl_wordBreakAfter,
11 tcl_wordBreakBefore - standard library of Tcl procedures
12
14 auto_execok cmd
15 auto_import pattern
16 auto_load cmd
17 auto_mkindex dir pattern pattern ...
18 auto_qualify command namespace
19 auto_reset
20 tcl_findLibrary basename version patch initScript enVarName varName
21 parray arrayName ?pattern?
22 tcl_endOfWord str start
23 tcl_startOfNextWord str start
24 tcl_startOfPreviousWord str start
25 tcl_wordBreakAfter str start
26 tcl_wordBreakBefore str start
27______________________________________________________________________________
28
30 Tcl includes a library of Tcl procedures for commonly-needed functions.
31 The procedures defined in the Tcl library are generic ones suitable for
32 use by many different applications. The location of the Tcl library is
33 returned by the info library command. In addition to the Tcl library,
34 each application will normally have its own library of support proce‐
35 dures as well; the location of this library is normally given by the
36 value of the $app_library global variable, where app is the name of the
37 application. For example, the location of the Tk library is kept in
38 the variable tk_library.
39 To access the procedures in the Tcl library, an application should
41 source the file init.tcl in the library, for example with the Tcl com‐
42 mand
43 source [file join [info library] init.tcl]
45 If the library procedure Tcl_Init is invoked from an application's
47 Tcl_AppInit procedure, this happens automatically. The code in
48 init.tcl will define the unknown procedure and arrange for the other
49 procedures to be loaded on-demand using the auto-load mechanism defined
50 below.
51
53 The following procedures are provided in the Tcl library:
54 auto_execok cmd
56 Determines whether there is an executable file or shell builtin
57 by the name cmd. If so, it returns a list of arguments to be
58 passed to exec to execute the executable file or shell builtin
59 named by cmd. If not, it returns an empty string. This command
60 examines the directories in the current search path (given by
61 the PATH environment variable) in its search for an executable
62 file named cmd. On Windows platforms, the search is expanded
63 with the same directories and file extensions as used by exec.
64 Auto_execok remembers information about previous searches in an
65 array named auto_execs; this avoids the path search in future
66 calls for the same cmd. The command auto_reset may be used to
67 force auto_execok to forget its cached information.
68 auto_import pattern
70 Auto_import is invoked during namespace import to see if the im‐
71 ported commands specified by pattern reside in an autoloaded li‐
72 brary. If so, the commands are loaded so that they will be
73 available to the interpreter for creating the import links. If
74 the commands do not reside in an autoloaded library, auto_import
75 does nothing. The pattern matching is performed according to
76 the matching rules of namespace import.
77 auto_load cmd
79 This command attempts to load the definition for a Tcl command
80 named cmd. To do this, it searches an auto-load path, which is
81 a list of one or more directories. The auto-load path is given
82 by the global variable auto_path if it exists. If there is no
83 auto_path variable, then the TCLLIBPATH environment variable is
84 used, if it exists. Otherwise the auto-load path consists of
85 just the Tcl library directory. Within each directory in the
86 auto-load path there must be a file tclIndex that describes one
87 or more commands defined in that directory and a script to eval‐
88 uate to load each of the commands. The tclIndex file should be
89 generated with the auto_mkindex command. If cmd is found in an
90 index file, then the appropriate script is evaluated to create
91 the command. The auto_load command returns 1 if cmd was suc‐
92 cessfully created. The command returns 0 if there was no index
93 entry for cmd or if the script did not actually define cmd (e.g.
94 because index information is out of date). If an error occurs
95 while processing the script, then that error is returned.
96 Auto_load only reads the index information once and saves it in
97 the array auto_index; future calls to auto_load check for cmd
98 in the array rather than re-reading the index files. The cached
99 index information may be deleted with the command auto_reset.
100 This will force the next auto_load command to reload the index
101 database from disk.
102 auto_mkindex dir pattern pattern ...
104 Generates an index suitable for use by auto_load. The command
105 searches dir for all files whose names match any of the pattern
106 arguments (matching is done with the glob command), generates an
107 index of all the Tcl command procedures defined in all the
108 matching files, and stores the index information in a file named
109 tclIndex in dir. If no pattern is given a pattern of *.tcl will
110 be assumed. For example, the command
111 auto_mkindex foo *.tcl
113 will read all the .tcl files in subdirectory foo and generate a
115 new index file foo/tclIndex.
116 Auto_mkindex parses the Tcl scripts by sourcing them into a
118 child interpreter and monitoring the proc and namespace commands
119 that are executed. Extensions can use the (undocumented)
120 auto_mkindex_parser package to register other commands that can
121 contribute to the auto_load index. You will have to read through
122 auto.tcl to see how this works.
123 Auto_mkindex_old (which has the same syntax as auto_mkindex)
125 parses the Tcl scripts in a relatively unsophisticated way: if
126 any line contains the word “proc” as its first characters then
127 it is assumed to be a procedure definition and the next word of
128 the line is taken as the procedure's name. Procedure defini‐
129 tions that do not appear in this way (e.g. they have spaces be‐
130 fore the proc) will not be indexed. If your script contains
131 “dangerous” code, such as global initialization code or proce‐
132 dure names with special characters like $, *, [ or ], you are
133 safer using auto_mkindex_old.
134 auto_reset
136 Destroys all the information cached by auto_execok and
137 auto_load. This information will be re-read from disk the next
138 time it is needed. Auto_reset also deletes any procedures
139 listed in the auto-load index, so that fresh copies of them will
140 be loaded the next time that they are used.
141 auto_qualify command namespace
143 Computes a list of fully qualified names for command. This list
144 mirrors the path a standard Tcl interpreter follows for command
145 lookups: first it looks for the command in the current name‐
146 space, and then in the global namespace. Accordingly, if com‐
147 mand is relative and namespace is not ::, the list returned has
148 two elements: command scoped by namespace, as if it were a com‐
149 mand in the namespace namespace; and command as if it were a
150 command in the global namespace. Otherwise, if either command
151 is absolute (it begins with ::), or namespace is ::, the list
152 contains only command as if it were a command in the global
153 namespace.
154 Auto_qualify is used by the auto-loading facilities in Tcl, both
156 for producing auto-loading indexes such as pkgIndex.tcl, and for
157 performing the actual auto-loading of functions at runtime.
158 tcl_findLibrary basename version patch initScript enVarName varName
160 This is a standard search procedure for use by extensions during
161 their initialization. They call this procedure to look for
162 their script library in several standard directories. The last
163 component of the name of the library directory is normally base‐
164 nameversion (e.g., tk8.0), but it might be “library” when in the
165 build hierarchies. The initScript file will be sourced into the
166 interpreter once it is found. The directory in which this file
167 is found is stored into the global variable varName. If this
168 variable is already defined (e.g., by C code during application
169 initialization) then no searching is done. Otherwise the search
170 looks in these directories: the directory named by the environ‐
171 ment variable enVarName; relative to the Tcl library directory;
172 relative to the executable file in the standard installation bin
173 or bin/arch directory; relative to the executable file in the
174 current build tree; relative to the executable file in a paral‐
175 lel build tree.
176 parray arrayName ?pattern?
178 Prints on standard output the names and values of all the ele‐
179 ments in the array arrayName, or just the names that match pat‐
180 tern (using the matching rules of string match) and their values
181 if pattern is given. ArrayName must be an array accessible to
182 the caller of parray. It may be either local or global.
183 tcl_endOfWord str start
185 Returns the index of the first end-of-word location that occurs
186 after a starting index start in the string str. An end-of-word
187 location is defined to be the first non-word character following
188 the first word character after the starting point. Returns -1
189 if there are no more end-of-word locations after the starting
190 point. See the description of tcl_wordchars and tcl_nonword‐
191 chars below for more details on how Tcl determines which charac‐
192 ters are word characters.
193 tcl_startOfNextWord str start
195 Returns the index of the first start-of-word location that oc‐
196 curs after a starting index start in the string str. A start-
197 of-word location is defined to be the first word character fol‐
198 lowing a non-word character. Returns -1 if there are no more
199 start-of-word locations after the starting point.
200 tcl_startOfPreviousWord str start
202 Returns the index of the first start-of-word location that oc‐
203 curs before a starting index start in the string str. Returns
204 -1 if there are no more start-of-word locations before the
205 starting point.
206 tcl_wordBreakAfter str start
208 Returns the index of the first word boundary after the starting
209 index start in the string str. Returns -1 if there are no more
210 boundaries after the starting point in the given string. The
211 index returned refers to the second character of the pair that
212 comprises a boundary.
213 tcl_wordBreakBefore str start
215 Returns the index of the first word boundary before the starting
216 index start in the string str. Returns -1 if there are no more
217 boundaries before the starting point in the given string. The
218 index returned refers to the second character of the pair that
219 comprises a boundary.
220
222 The following global variables are defined or used by the procedures in
223 the Tcl library. They fall into two broad classes, handling unknown
224 commands and packages, and determining what are words.
225 AUTOLOADING AND PACKAGE MANAGEMENT VARIABLES
227 auto_execs
228 Used by auto_execok to record information about whether particu‐
229 lar commands exist as executable files.
230 auto_index
232 Used by auto_load to save the index information read from disk.
233 auto_noexec
235 If set to any value, then unknown will not attempt to auto-exec
236 any commands.
237 auto_noload
239 If set to any value, then unknown will not attempt to auto-load
240 any commands.
241 auto_path
243 If set, then it must contain a valid Tcl list giving directories
244 to search during auto-load operations (including for package in‐
245 dex files when using the default package unknown handler). This
246 variable is initialized during startup to contain, in order: the
247 directories listed in the TCLLIBPATH environment variable, the
248 directory named by the tcl_library global variable, the parent
249 directory of tcl_library, the directories listed in the tcl_pkg‐
250 Path variable. Additional locations to look for files and pack‐
251 age indices should normally be added to this variable using lap‐
252 pend.
253 env(TCL_LIBRARY)
255 If set, then it specifies the location of the directory contain‐
256 ing library scripts (the value of this variable will be assigned
257 to the tcl_library variable and therefore returned by the com‐
258 mand info library). If this variable is not set then a default
259 value is used.
260 env(TCLLIBPATH)
262 If set, then it must contain a valid Tcl list giving directories
263 to search during auto-load operations. Directories must be
264 specified in Tcl format, using “/” as the path separator, re‐
265 gardless of platform. This variable is only used when initial‐
266 izing the auto_path variable.
267 WORD BOUNDARY DETERMINATION VARIABLES
269 These variables are only used in the tcl_endOfWord,
270 tcl_startOfNextWord, tcl_startOfPreviousWord, tcl_wordBreakAfter, and
271 tcl_wordBreakBefore commands.
272 tcl_nonwordchars
274 This variable contains a regular expression that is used by rou‐
275 tines like tcl_endOfWord to identify whether a character is part
276 of a word or not. If the pattern matches a character, the char‐
277 acter is considered to be a non-word character. On Windows
278 platforms, spaces, tabs, and newlines are considered non-word
279 characters. Under Unix, everything but numbers, letters and un‐
280 derscores are considered non-word characters.
281 tcl_wordchars
283 This variable contains a regular expression that is used by rou‐
284 tines like tcl_endOfWord to identify whether a character is part
285 of a word or not. If the pattern matches a character, the char‐
286 acter is considered to be a word character. On Windows plat‐
287 forms, words are comprised of any character that is not a space,
288 tab, or newline. Under Unix, words are comprised of numbers,
289 letters or underscores.
290
292 env(n), info(n), re_syntax(n)
293
295 auto-exec, auto-load, library, unknown, word, whitespace
296Tcl 8.0 library(n)