Is set?

[Anansi]

Is there a way to return (without crashing the procedure) whether a variable is set or not set? I need this specifically for array elements, but it would also be useful (and work in a similar manner) for normal variables.

I looked in the Tcl manual and could find nothing.

[r0t3n]

Code: Select all

info exists varname - returns 1 if set, or 0 if not

info exists arrayname(arrayelement) - returns 1 if set, or 0 if not

To see if an array is set:

Code: Select all

array exists arrayname - returns 1 if the array is set, or 0 if not

[Anansi]

array exists was easy to find, but not info exists Thanks.

[Anansi]

Can I declare a variable as an array without actually writing anything on it? I want a global array to be initialized within a procedure, but if I don't initialize it outside the procedure when I try to initialize it inside it returns the "not an array" error. I'm using "global arrayname".

Ok, nevermind. Rehash just didn't reset the variables properly. A restart solved it.

[awyeah]

You mean something like this:

Code: Select all

proc name {arg1 arg2 arg3} {
 global myarray
 if {[info exists myarray($arg1)]} {
  #whatever you want to do here
 }
}

[nml375]

You could always create an empty array using this (this requires "myvar" to either be an array or not set at all.):

Code: Select all

array set myvar ""

Or perhaps something like this to make sure the variable is unset prior initialization:

Code: Select all

unset myvar
array set myvar ""

Also keep in mind, that the global-command really does'nt create, alter or otherwize directly affect any variable. All it does is link the local variable (within a proc) to the corresponding globalspace variable.

[Anansi]

Right, but it was bitching about the previously untouched variable "not being an array" when I tried to set one of its members. unsetting the variable just prior to setting it was not an option because the procedure that set the variable was called several times to set different members - unsetting the variable before setting it would mean it would never have more than one member. Fortunately, it was just a problem of eggdrop not reseting the variables well.

[nml375]

Maybe I should've been alittle clearer, the code above was intended to initialize the variable upon reset/rehash, and not be used within various procs ("array set" will overwrite any existing data in the array).

[awyeah]

Whats the use of setting an empty array and then unsetting it anyway?

[nml375]

Whats the use of setting an empty array and then unsetting it anyway?

None to my knowledge..
There is, however, a point in unsetting it and then creating an empty array