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



** See Also **

   [info]:   

   [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 **

If the script currently being evaluated was read from a file, i.e. a call to
`Tcl_EvalFile()` is active or `[source]` is active somewhere up the current
call stack, `[info] script` returns the name of that file.  `[info] script`
returns the [empty string] if no evaluated script at any level was read from a
file.

If ''filename'' is given, then for the remainder of the evaluation of the
current script, `[info] script` returns that value.  It is useful in virtual
filesystem applictions to set a new value of `[info] script`. 

`[info] script` is used, for example, to `[source]` other scripts it depends
on.  For example:

======
source [file join [file dirname [info script]] tkcon.tcl]
======

To be sure no symbolic links are leading to an unexpected file, use a more
verbose variant:

======
source [file join [file dirname [file dirname [file normalize [file join [info script] ...]]]] tkcon.tcl]
======


----

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P.S. Note that `Tcl_EvalFile()` is obsolete.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



** Page Authors **

   [escargo]:   

   [PYK]:   


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