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From: greg <gregor.ebbing@gmx.de>
Newsgroups: comp.lang.tcl
Subject: Re: oo::class - my variable vs variable
Date: Fri, 5 Jul 2024 23:01:46 +0200
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Am 04.07.24 um 09:17 schrieb Mark Summerfield:
> I am trying to learn TclOO. I have created two classes P and Q which
> appear to have identical behavior. Class P uses "my variable" and Q uses
> "variable". Can someone explain the difference between them. (I am
> familiar with Python and Go if that's any help with explaining.)
> 
> oo::class create P {
>      constructor {{x 0} {y 0}} {
>          my variable x_
>          my variable y_
>          set x_ $x
>          set y_ $y
>      }
> 
>      method x {} {
>          my variable x_
>          return $x_
>      }
> 
>      method set_x {x} {
>          if {![string is integer -strict $x]} {
>              throw NOT_AN_INT "x must be an int not \"$x\""
>          }
>          my variable x_
>          set x_ $x
>      }
> 
>      method y {} {
>          my variable y_
>          return $y_
>      }
> }
> 
> oo::class create Q {
>      constructor {{x 0} {y 0}} {
>          variable x_
>          variable y_
>          set x_ $x
>          set y_ $y
>      }
> 
>      method x {} {
>          variable x_
>          return $x_
>      }
> 
>      method set_x {x} {
>          if {![string is integer -strict $x]} {
>              throw NOT_AN_INT "x must be an int not \"$x\""
>          }
>          variable x_
>          set x_ $x
>      }
> 
>      method y {} {
>          variable y_
>          return $y_
>      }
> }
> 
> puts "P"
> set p1 [P new]
> puts "p1 x=[$p1 x] y=[$p1 y]"
> $p1 set_x 5
> puts "p1 x=[$p1 x] y=[$p1 y]"
> try {$p1 set_x "invalid"} trap {} err { puts $err }
> set p2 [P new 0 -8]
> puts "p2 x=[$p2 x] y=[$p2 y]"
> $p2 set_x 17
> puts "p2 x=[$p2 x] y=[$p2 y]"
> puts "p1 x=[$p1 x] y=[$p1 y]"
> 
> puts "Q"
> set q1 [Q new]
> puts "q1 x=[$q1 x] y=[$q1 y]"
> $q1 set_x 5
> puts "q1 x=[$q1 x] y=[$q1 y]"
> try {$q1 set_x "invalid"} trap {} err { puts $err }
> set q2 [Q new 0 -8]
> puts "q2 x=[$q2 x] y=[$q2 y]"
> $q2 set_x 17
> puts "q2 x=[$q2 x] y=[$q2 y]"
> puts "q1 x=[$q1 x] y=[$q1 y]"

Hello
if the website is not known:

https://wiki.tcl-lang.org/page/Variables+in+TclOO

Gregor