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Text File | 1995-07-26 | 16.0 KB | 263 lines

lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) TTTTccccllll (((( )))) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) _________________________________________________________________ NNNNAAAAMMMMEEEE library - standard library of Tcl procedures SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk _c_m_d aaaauuuuttttoooo____llllooooaaaadddd _c_m_d aaaauuuuttttoooo____mmmmkkkkiiiinnnnddddeeeexxxx _d_i_r _p_a_t_t_e_r_n _p_a_t_t_e_r_n ... aaaauuuuttttoooo____rrrreeeesssseeeetttt ppppaaaarrrrrrrraaaayyyy _a_r_r_a_y_N_a_m_e uuuunnnnkkkknnnnoooowwwwnnnn _c_m_d ?_a_r_g _a_r_g ...? _________________________________________________________________ IIIINNNNTTTTRRRROOOODDDDUUUUCCCCTTTTIIIIOOOONNNN Tcl includes a library of Tcl procedures for commonly-needed functions. The procedures defined in the Tcl library are generic ones suitable for use by many different applications. The location of the Tcl library is returned by the iiiinnnnffffoooo lllliiiibbbbrrrraaaarrrryyyy command. In addition to the Tcl library, each application will normally have its own library of support procedures as well; the location of this library is normally given by the value of the $$$$_a_p_p____lllliiiibbbbrrrraaaarrrryyyy global variable, where _a_p_p is the name of the application. For example, the location of the Tk library is kept in the variable $$$$ttttkkkk____lllliiiibbbbrrrraaaarrrryyyy. To access the procedures in the Tcl library, an application should source the file iiiinnnniiiitttt....ttttccccllll in the library, for example with the Tcl command ssssoooouuuurrrrcccceeee [[[[iiiinnnnffffoooo lllliiiibbbbrrrraaaarrrryyyy]]]]////iiiinnnniiiitttt....ttttccccllll This will define the uuuunnnnkkkknnnnoooowwwwnnnn procedure and arrange for the other procedures to be loaded on-demand using the auto-load mechanism defined below. CCCCOOOOMMMMMMMMAAAANNNNDDDD PPPPRRRROOOOCCCCEEEEDDDDUUUURRRREEEESSSS The following procedures are provided in the Tcl library: aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk _c_m_d Determines whether there is an executable file by the name _c_m_d. This command examines the directories in the current search path (given by the PATH enviornment variable) to see if there is an executable file named _c_m_d in any of those directories. If so, it returns 1; if not it returns 0. AAAAuuuuttttoooo____eeeexxxxeeeecccc remembers information about previous searches in an array named aaaauuuuttttoooo____eeeexxxxeeeeccccssss; this avoids the path search in future calls for the same _c_m_d. The command aaaauuuuttttoooo____rrrreeeesssseeeetttt may be used to force aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk to forget its cached information. Page 1 (printed 7/17/95) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) TTTTccccllll (((( )))) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) aaaauuuuttttoooo____llllooooaaaadddd _c_m_d This command attempts to load the definition for a Tcl command named _c_m_d. To do this, it searches an _a_u_t_o- _l_o_a_d _p_a_t_h, which is a list of one or more directories. The auto-load path is given by the global variable $$$$aaaauuuuttttoooo____ppppaaaatttthhhh if it exists. If there is no $$$$aaaauuuuttttoooo____ppppaaaatttthhhh variable, then the TCLLIBPATH environment variable is used, if it exists. Otherwise the auto-load path consists of just the Tcl library directory. Within each directory in the auto-load path there must be a file ttttccccllllIIIInnnnddddeeeexxxx that describes one or more commands | defined in that directory and a script to evaluate to | load each of the commands. The ttttccccllllIIIInnnnddddeeeexxxx file should be | generated with the aaaauuuuttttoooo____mmmmkkkkiiiinnnnddddeeeexxxx command. If _c_m_d is | found in an index file, then the appropriate script is | evaluated to create the command. The aaaauuuuttttoooo____llllooooaaaadddd command returns 1 if _c_m_d was successfully created. The command returns 0 if there was no index entry for _c_m_d or if the script didn't actually define _c_m_d (e.g. because index information is out of date). If an error occurs while processing the script, then that error is returned. AAAAuuuuttttoooo____llllooooaaaadddd only reads the index information once and saves it in the array aaaauuuuttttoooo____iiiinnnnddddeeeexxxx; future calls to aaaauuuuttttoooo____llllooooaaaadddd check for _c_m_d in the array rather than re- reading the index files. The cached index information may be deleted with the command aaaauuuuttttoooo____rrrreeeesssseeeetttt. This will force the next aaaauuuuttttoooo____llllooooaaaadddd command to reload the index database from disk. aaaauuuuttttoooo____mmmmkkkkiiiinnnnddddeeeexxxx _d_i_r _p_a_t_t_e_r_n _p_a_t_t_e_r_n ... Generates an index suitable for use by aaaauuuuttttoooo____llllooooaaaadddd. The | command searches _d_i_r for all files whose names match | any of the _p_a_t_t_e_r_n arguments (matching is done with the gggglllloooobbbb command), generates an index of all the Tcl command procedures defined in all the matching files, and stores the index information in a file named ttttccccllllIIIInnnnddddeeeexxxx in _d_i_r. For example, the command aaaauuuuttttoooo____mmmmkkkkiiiinnnnddddeeeexxxx ffffoooooooo ****....ttttccccllll will read all the ....ttttccccllll files in subdirectory ffffoooooooo and generate a new index file ffffoooooooo////ttttccccllllIIIInnnnddddeeeexxxx. AAAAuuuuttttoooo____mmmmkkkkiiiinnnnddddeeeexxxx parses the Tcl scripts in a relatively unsophisticated way: if any line contains the word pppprrrroooocccc as its first characters then it is assumed to be a procedure definition and the next word of the line is taken as the procedure's name. Procedure definitions that don't appear in this way (e.g. they have spaces before the pppprrrroooocccc) will not be indexed. Page 2 (printed 7/17/95) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) TTTTccccllll (((( )))) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) aaaauuuuttttoooo____rrrreeeesssseeeetttt Destroys all the information cached by aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk and aaaauuuuttttoooo____llllooooaaaadddd. This information will be re-read from disk the next time it is needed. AAAAuuuuttttoooo____rrrreeeesssseeeetttt also deletes any procedures listed in the auto-load index, so that fresh copies of them will be loaded the next time that they're used. ppppaaaarrrrrrrraaaayyyy _a_r_r_a_y_N_a_m_e Prints on standard output the names and values of all the elements in the array _a_r_r_a_y_N_a_m_e. AAAArrrrrrrraaaayyyyNNNNaaaammmmeeee must be an array accessible to the caller of ppppaaaarrrrrrrraaaayyyy. It may be either local or global. uuuunnnnkkkknnnnoooowwwwnnnn _c_m_d ?_a_r_g _a_r_g ...? This procedure is invoked automatically by the Tcl interpreter whenever the name of a command doesn't exist. The uuuunnnnkkkknnnnoooowwwwnnnn procedure receives as its arguments the name and arguments of the missing command. UUUUnnnnkkkknnnnoooowwwwnnnn | first calls aaaauuuuttttoooo____llllooooaaaadddd to load the command. If this succeeds, then it executes the original command with its original arguments. If the auto-load fails then uuuunnnnkkkknnnnoooowwwwnnnn calls aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk to see if there is an executable file by the name _c_m_d. If so, it invokes the Tcl eeeexxxxeeeecccc command with _c_m_d and all the _a_r_g_s as arguments. If _c_m_d can't be auto-executed, uuuunnnnkkkknnnnoooowwwwnnnn checks to see if the command was invoked at top-level and outside of any script. If so, then uuuunnnnkkkknnnnoooowwwwnnnn takes takes two additional steps. First, it sees if _c_m_d has one of the following three forms: !!!!!!!!, !!!!_e_v_e_n_t, or ^^^^_o_l_d^^^^_n_e_w?^^^^?. If so, then uuuunnnnkkkknnnnoooowwwwnnnn carries out history substitution in the same way that ccccsssshhhh would for these constructs. Second, and last, uuuunnnnkkkknnnnoooowwwwnnnn checks to see if _c_m_d is a unique abbreviation for an existing Tcl command. If so, it expands the command name and executes the command with the original arguments. If none of the above efforts has been able to execute the command, uuuunnnnkkkknnnnoooowwwwnnnn generates an error return. If the global variable aaaauuuuttttoooo____nnnnoooollllooooaaaadddd is defined, then the auto- load step is skipped. If the global variable aaaauuuuttttoooo____nnnnooooeeeexxxxeeeecccc is defined then the auto-exec step is skipped. Under normal circumstances the return value from uuuunnnnkkkknnnnoooowwwwnnnn is the return value from the command that was eventually executed. VVVVAAAARRRRIIIIAAAABBBBLLLLEEEESSSS The following global variables are defined or used by the procedures in the Tcl library: aaaauuuuttttoooo____eeeexxxxeeeeccccssss Used by aaaauuuuttttoooo____eeeexxxxeeeeccccooookkkk to record information about whether Page 3 (printed 7/17/95) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) TTTTccccllll (((( )))) lllliiiibbbbrrrraaaarrrryyyy((((nnnn)))) particular commands exist as executable files. aaaauuuuttttoooo____iiiinnnnddddeeeexxxx Used by aaaauuuuttttoooo____llllooooaaaadddd to save the index information read from disk. aaaauuuuttttoooo____nnnnooooeeeexxxxeeeecccc If set to any value, then uuuunnnnkkkknnnnoooowwwwnnnn will not attempt to auto-exec any commands. aaaauuuuttttoooo____nnnnoooollllooooaaaadddd If set to any value, then uuuunnnnkkkknnnnoooowwwwnnnn will not attempt to auto-load any commands. aaaauuuuttttoooo____ppppaaaatttthhhh If set, then it must contain a valid Tcl list giving directories to search during auto-load operations. eeeennnnvvvv((((TTTTCCCCLLLL____LLLLIIIIBBBBRRRRAAAARRRRYYYY)))) If set, then it specifies the location of the directory containing library scripts (the value of this variable will be returned by the command iiiinnnnffffoooo lllliiiibbbbrrrraaaarrrryyyy). If this variable isn't set then a default value is used. eeeennnnvvvv((((TTTTCCCCLLLLLLLLIIIIBBBBPPPPAAAATTTTHHHH)))) If set, then it must contain a valid Tcl list giving directories to search during auto-load operations. This variable is only used if aaaauuuuttttoooo____ppppaaaatttthhhh is not defined. uuuunnnnkkkknnnnoooowwwwnnnn____aaaaccccttttiiiivvvveeee This variable is set by uuuunnnnkkkknnnnoooowwwwnnnn to indicate that it is active. It is used to detect errors where uuuunnnnkkkknnnnoooowwwwnnnn recurses on itself infinitely. The variable is unset before uuuunnnnkkkknnnnoooowwwwnnnn returns. KKKKEEEEYYYYWWWWOOOORRRRDDDDSSSS auto-exec, auto-load, library, unknown Page 4 (printed 7/17/95)