On Friday 09 April 2004 11:27, Muli Ben-Yehuda wrote: > > 3. What the @$([EMAIL PROTECTED] is the difference between "my" and "local"? Which > > one should I use here? > > http://prometheus.frii.com/~gnat/yapc/2000-stages/slide21.html
I didn't like so much the "dumbed down" type of explatanion in this slide, so here is my take: 1. "my" does early binding between variable name and variable storage (when the variable is defined) while "local" does late binding (when the variable is used). 2. This is very similar to the logical difference between hard link and symbolic link in the file system. 3. Technically, "my" variables are allocated on the call stack and thus behaves just like automatic variables in C. "local" variables are actually global variables which are looked up through the symbol table. What the "local" keyword does is temporarily save the global value and restore it automatically when we exit the scope. 4. Until perl-5 arrived (circa 94) only "local" existed. That's the historical reason for the non-intuitive name. During perl-6 development it was suggested to create a better term, something like "tempval" which describes more accurately its semantics (I didn't follow through to check if it was accepted after all). -- Oron Peled Voice/Fax: +972-4-8228492 [EMAIL PROTECTED] http://www.actcom.co.il/~oron "Beware of bugs in the above code; I have only proved it correct, not tried it." -- Donald E. Knuth ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
