1Tcl_RegisterConfig(3) Tcl Library Procedures Tcl_RegisterConfig(3)
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8 Tcl_RegisterConfig - procedures to register embedded configuration
9 information
10
12 #include <tcl.h>
13 void
15 Tcl_RegisterConfig(interp, pkgName, configuration, valEncoding)
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19 Tcl_Interp *interp (in) Refers to the interpreter the
20 embedded configuration informa‐
21 tion is registered for. Must
22 not be NULL.
23 const char *pkgName (in) Contains the name of the pack‐
25 age registering the embedded
26 configuration as ASCII string.
27 This means that this informa‐
28 tion is in UTF-8 too. Must not
29 be NULL.
30 Tcl_Config *configuration (in) Refers to an array of Tcl_Con‐
32 fig entries containing the
33 information embedded in the
34 binary library. Must not be
35 NULL. The end of the array is
36 signaled by either a key iden‐
37 tical to NULL, or a key refer‐
38 ring to the empty string.
39 const char *valEncoding (in) Contains the name of the encod‐
41 ing used to store the configu‐
42 ration values as ASCII string.
43 This means that this informa‐
44 tion is in UTF-8 too. Must not
45 be NULL.
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50 The function described here has its base in TIP 59 and provides exten‐
51 sions with support for the embedding of configuration information into
52 their binary library and the generation of a Tcl-level interface for
53 querying this information.
54 To embed configuration information into their binary library an exten‐
56 sion has to define a non-volatile array of Tcl_Config entries in one if
57 its source files and then call Tcl_RegisterConfig to register that
58 information.
59 Tcl_RegisterConfig takes four arguments; first, a reference to the
61 interpreter we are registering the information with, second, the name
62 of the package registering its configuration information, third, a
63 pointer to an array of structures, and fourth a string declaring the
64 encoding used by the configuration values.
65 The string valEncoding contains the name of an encoding known to Tcl.
67 All these names are use only characters in the ASCII subset of UTF-8
68 and are thus implicitly in the UTF-8 encoding. It is expected that keys
69 are legible English text and therefore using the ASCII subset of UTF-8.
70 In other words, they are expected to be in UTF-8 too. The values asso‐
71 ciated with the keys can be any string however. For these the contents
72 of valEncoding define which encoding was used to represent the charac‐
73 ters of the strings.
74 Each element of the configuration array refers to two strings contain‐
76 ing the key and the value associated with that key. The end of the
77 array is signaled by either an empty key or a key identical to NULL.
78 The function makes no copy of the configuration array. This means that
79 the caller has to make sure that the memory holding this array is never
80 released. This is the meaning behind the word non-volatile used ear‐
81 lier. The easiest way to accomplish this is to define a global static
82 array of Tcl_Config entries. See the file “generic/tclPkgConfig.c” in
83 the sources of the Tcl core for an example.
84 When called Tcl_RegisterConfig will
86 (1) create a namespace having the provided pkgName, if not yet
88 existing.
89 (2) create the command pkgconfig in that namespace and link it to
91 the provided information so that the keys from _configuration_
92 and their associated values can be retrieved through calls to
93 pkgconfig.
94 The command pkgconfig will provide two subcommands, list and get:
96 ::pkgName::pkgconfig list
98 Returns a list containing the names of all defined keys.
99 ::pkgName::pkgconfig get key
101 Returns the configuration value associated with the spec‐
102 ified key.
103
105 The Tcl_Config structure contains the following fields:
106 typedef struct Tcl_Config {
108 const char* key;
109 const char* value;
110 } Tcl_Config;
111
113 embedding, configuration, binary library
114Tcl 8.4 Tcl_RegisterConfig(3)