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Tcl_RegisterConfig(3) Tcl Library Procedures Tcl_RegisterConfig(3) ______________________________________________________________________________ NAME Tcl_RegisterConfig - procedures to register embedded configuration in- formation SYNOPSIS #include <tcl.h> Tcl_RegisterConfig(interp, pkgName, configuration, valEncoding) ARGUMENTS Tcl_Interp *interp (in) Refers to the interpreter the embedded configuration informa- tion is registered for. Must not be NULL. const char *pkgName (in) Contains the name of the pack- age registering the embedded configuration as ASCII string. This means that this informa- tion is in UTF-8 too. Must not be NULL. const Tcl_Config *configuration (in) Refers to an array of Tcl_Con- fig entries containing the in- formation embedded in the li- brary. Must not be NULL. The end of the array is signaled by either a key identical to NULL, or a key referring to the empty string. const char *valEncoding (in) Contains the name of the encod- ing used to store the configu- ration values as ASCII string. This means that this informa- tion is in UTF-8 too. Must not be NULL. ______________________________________________________________________________ DESCRIPTION The function described here has its base in TIP 59 and provides exten- sions with support for the embedding of configuration information into their library and the generation of a Tcl-level interface for querying this information. To embed configuration information into their library an extension has to define a non-volatile array of Tcl_Config entries in one if its source files and then call Tcl_RegisterConfig to register that informa- tion. Tcl_RegisterConfig takes four arguments; first, a reference to the in- terpreter we are registering the information with, second, the name of the package registering its configuration information, third, a pointer to an array of structures, and fourth a string declaring the encoding used by the configuration values. The string valEncoding contains the name of an encoding known to Tcl. All these names are use only characters in the ASCII subset of UTF-8 and are thus implicitly in the UTF-8 encoding. It is expected that keys are legible English text and therefore using the ASCII subset of UTF-8. In other words, they are expected to be in UTF-8 too. The values asso- ciated with the keys can be any string however. For these the contents of valEncoding define which encoding was used to represent the charac- ters of the strings. Each element of the configuration array refers to two strings contain- ing the key and the value associated with that key. The end of the ar- ray is signaled by either an empty key or a key identical to NULL. The function makes no copy of the configuration array. This means that the caller has to make sure that the memory holding this array is never re- leased. This is the meaning behind the word non-volatile used earlier. The easiest way to accomplish this is to define a global static array of Tcl_Config entries. See the file "generic/tclPkgConfig.c" in the sources of the Tcl core for an example. When called Tcl_RegisterConfig will (1) create a namespace having the provided pkgName, if not yet ex- isting. (2) create the command pkgconfig in that namespace and link it to the provided information so that the keys from configuration and their associated values can be retrieved through calls to pkg- config. The command pkgconfig will provide two subcommands, list and get: ::pkgName::pkgconfig list Returns a list containing the names of all defined keys. ::pkgName::pkgconfig get key Returns the configuration value associated with the spec- ified key. TCL_CONFIG The Tcl_Config structure contains the following fields: typedef struct { const char *key; const char *value; } Tcl_Config; KEYWORDS embedding, configuration, library Tcl 8.4 Tcl_RegisterConfig(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | TCL_CONFIG | KEYWORDS
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