Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!)

Ok... we'd figured that far when jeffa got:

sub bar {
         my $str = "foo";
         return scalar reverse $str;
 }
 
 print chop bar();
 
captvanhalen: $ perl foo
 Can't modify non-lvalue subroutine call in chop at foo line 6, near "
+);"
 Execution of foo aborted due to compilation errors.
[download]

Now, my question is... that's not very "DWIM" of perl... (at least not to me!) Why does reverse not return an lvalue?

Comment on Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!) Download Code

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Re: Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!) by merlyn (Sage) on Dec 26, 2001 at 21:55 UTC
How often have you wanted to say: `reverse $foo = "merlyn";` [download] in sensible code? That's why it doesn't return an lvalue! -- Randal L. Schwartz, Perl hacker	[reply] [d/l]
Re: Re: Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!) by eduardo (Curate) on Dec 26, 2001 at 22:03 UTC
Definite agreement... `reverse $foo = "merlyn";` makes little to no sense. However, `chop reverse $foo;` does seem relatively reasonable... (though I see how it quickly goes to hell in a handbasket.) I remember when in my Data Structures in C++ class they tried explaining the reason to overload some operators as lvalues, and some not... it always seemed like you could find a scenario where you may want that functionality (though I doubt `2 + 2 = $foo;` would ever be a good one :) Well... thanks to everyone for the answers! I am going to agree that it really makes very little sense to let reverse return an lvalue... though I think the obfuscation "value" alone may warrant it :)	[reply] [d/l] [select]
Re: Re: Re: Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!) by Juerd (Abbot) on Dec 26, 2001 at 22:08 UTC
though I doubt `2 + 2 = $foo;` would ever be a good one :) "2 + 2 equals $foo, for certain values of 2"... hmmm... No, really, i think `2 + $bar = 3` would be a nice way to write `$bar = 1`, but _very_ hard to make. `2;0 juerd@ouranos:~$ perl -e'undef christmas' Segmentation fault 2;139 juerd@ouranos:~$` [download]	[reply] [d/l] [select]
Re: Re: Re: First char out of a string & surprises with errors on chop reverse $string (that doesn't work!) by Juerd (Abbot) on Dec 26, 2001 at 21:56 UTC
For the same reason `2 + 2` doesn't return an lvalue. Besides, there's no reason for having reverse return an lvalue. TMTOWTDI, and `reverse chop` was never supposed to be one of them. Still, there are a lot of other WTDI. `2;0 juerd@ouranos:~$ perl -e'undef christmas' Segmentation fault 2;139 juerd@ouranos:~$` [download]	[reply] [d/l] [select]


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