From: ts <decoux@...>
Date: 2002-08-26T19:26:07+09:00
Subject: Re: warning modifying constant & 'global constant'

>>>>> "D" == David Garamond <davegaramond@icqmail.com> writes:

D> i want to protect some global variables without having to resort to 
D> setting $SAFE to 4. can we use some proxying mechanism, or override an 
D> object method to trap assignment/binding? freeze() only protect the 
D> object value, and does not prevent rebinding.

 ruby has internally read only variables, for example :

pigeon% ruby -e '$LOAD_PATH = "aaa"'
-e:1: can't set variable $LOAD_PATH (NameError)
pigeon% 

 but

pigeon% ruby -e '$LOAD_PATH << "aaa"'
pigeon% 

 well,

pigeon% ruby -e '$LOAD_PATH.freeze; $LOAD_PATH << "aaa"'
-e:1:in `<<': can't modify frozen array (TypeError)
        from -e:1
pigeon% 

 but

pigeon% ruby -e '$LOAD_PATH.freeze; $LOAD_PATH[0] << "aaa"'
pigeon% 

 etc



Guy Decoux