Testing and reading env variables on Windows 
Author Message
 Testing and reading env variables on Windows

Tcl 8.2b2 Bug:  Generated by Scriptics' bug entry form at
        http://www.*-*-*.com/
Responses to this post are encouraged.
------

Submitted by:  Ingemar Hansson
OperatingSystem:  Windows NT
OperatingSystemVersion:  v4.0 SP5
Synopsis:  Testing and reading env variables on Windows

ReproducibleScript:
    Set an environment variable (at DOS-level):
    set tVar=1

    # This test will return 0
    if {[info exists env(TVAR)]} {
        set tv $env(TVAR)
    }
    # The variable tv will be set !!!
    set tv $env(TVAR)

    # Now this test will return 1 !!!
    if {[info exists env(TVAR)]} {
        set tv $env(TVAR)
    }

ObservedBehavior:
    "info exists" doesn't find env variables that an access the env array
    does.

DesiredBehavior:
    There seems to be some undocumentet feature when accessing the env
    variable. Character case of index to the array doesn't matter (even
    though the documentation says it does). I like that (!!!) because that's
    the behaviour in the operating system. (Maybe it's an OS API that does
    this?).
    But the "info exists" command fails until an access with equal character
    case is done.

Comments:
    This isn't too hard to work around. Instead of the following
    construction

    if {[info exists env(TVAR)]} {
        do something
    }

    use

    if {![catch {set env(TVAR)}]} {
        do something
    }



Sun, 27 Jan 2002 03:00:00 GMT  
 
 [ 1 post ] 

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