Updated 2014-05-25 22:50:37 by RLE

info script ?filename? returns or sets the name of the file containing the script currently being evaluated.

See Also  edit

main script
detect when a script is used as the main script in an interpreter. Often used in scripted libraries to run self tests.

Description  edit

If a Tcl script file is currently being evaluated, i.e. there is a call to Tcl_EvalFile() active or source is active somewhere up the current call stack, then info script returns the name of the innermost file being processed. If filename is specified, then filename becomes the new return value info script for the remainder of the evaluation of the current script. Setting a new value of info script is useful in virtual file system applications.

If there is no script currently being evaluated, info script returns an empty string.

MJL: I find the description from the manual page rather confusing and poorly worded. So here's my attempt at an explanation:

Every Tcl interpreter has an associated "script file" Tcl object, which is initially empty. This can be set by invoking info script new_value and retrieved by invoking info script. The function Tcl_FSEvalFile(), which is called by the source command, modifies the script file object as follows: The current value is saved, then set to the name of the file to be evaluated. The file's contents are evaluated, and then the saved value is restored.

P.S. Note that Tcl_EvalFile() is obsolete.

Moreover, as dburns noted in the Chatroom, "I believe info script is what you want, but the command must be executed before source finishes reading in the script...hence the info script must be executed at the top-level within the script file...if embedded in a proc within the script, it's 'too late' by the time the proc is run for 'info script' to work correctly"

schlenk 2005-04-24: The man page implies that it is impossible to get the filename a proc comes from after Tcl_FSEvalFile() or source has returned. So the only way to do it is to register this info while creating the proc or to use something like grep to look for it inside the filesystem.
# move the old proc command out of the way
rename proc ::tcl::proc
# create a replacement proc that registers all occurrences of proc creation
# into the global proc_to_filename_map variable
::tcl::proc proc args {
    global proc_to_filename_map
    set proc_to_filename_map([lindex $args 0]) [info script]
    uplevel 1 [linsert $args 0 ::tcl::proc]

With this one can easily find the file for a proc by looking into the array. For Tcl 8.4 and later one could use execution traces on the proc command to do the same thing without renaming proc, implementation is left as an exercise.

escargo 2005-08-23: There is another idiom where info script is used: where a script needs to source other related scripts so that it can run. For example:
source [file join [file dirname [info script]] tkcon.tcl]

See Also  edit

main script