Re: Should chomping a constant always raise an error?

Personally, it makes a lot of sense. Sure if there's no need to chomp a value then it shouldn't hurt. However the function *must* be assuming the input it to be modifyied in some way otherwise you'd not pass a value to it that you expect to be modified.

sub modify {
   chomp( $_[0] );
   # whatever else happens, you've just potentially modified $_[0]
}

modify('fred');
# What would you expect to happen to 'fred'?

my $f ="fred\n";
modify($f);
print $f;
#fred
[download]

sub modify2 {
   # Create a copy of the input
   my $input = $_[0];
   chomp($input);
}

modify('fred');
# works now because we're not modifying the input, but a copy of it.

my $f ="fred\n";
modify($f);
print $f;
#fred\n
[download]

Cheers!
Rick
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Comment on Re: Should chomping a constant always raise an error? Select or Download Code

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Re: can this be turned into a compile-time error? by Thilosophy (Curate) on Mar 11, 2005 at 03:56 UTC
`sub modify { chomp( $_[0] ); # whatever else happens, you've just potentially modified $_[0] } modify('fred'); # What would you expect to happen to 'fred'?` [download] Great example. For those who did not try it out, it causes a runtime exception: `Modification of a read-only value attempted at /tmp/t.pl line 2.` [download] Can `modify` somehow be declared to only take a modifiable parameter, so that we can have a compile-time error (as happens with the core `chomp`)? `Can't modify constant item in modify at -e line 1, at end of line Execution of -e aborted due to compilation errors.` [download]	[reply] [d/l] [select]
Re^2: can this be turned into a compile-time error? by QM (Parson) on Mar 11, 2005 at 18:54 UTC
Can modify somehow be declared to only take a modifiable parameter, so that we can have a compile-time error (as happens with the core chomp)? Playing Devil's Advocate, will this work? `chomp(foo(",",@list))` [download] Don't know? How about this? `chomp(join(",",@list))` [download] It seems, off the top of my naive head, that the argument to `chomp` would have to be an l-value to be guaranteed to be modifiable. Is that what you want? -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l] [select]


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