Re: Testing <> for undefined

*fixing my previous post:

You could also do something like that:

# Test if the is an argument 

if(!@ARGV) 
   { 
   die "My help message\n"; 
   } 

# Test if the argument is a file 
if(! -e $ARGV[0]) 
   { 
   print "File $ARGV0 does not exist\n"; 
   }
[download]

's -DBC

Comment on Re: Testing <> for undefined Download Code

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Re^2: Testing <> for undefined by BbTrumpet (Acolyte) on Jul 08, 2004 at 16:41 UTC
I have done this in the past, and it seems to work fine: my $file = $ARGV[0] ? $ARGV[0] : die "USAGE: prog.pl file_pathname\n"; open(FILE,"$file") or die "Unable to open file $file\n";	[reply]
Re^3: Testing <> for undefined by Roy Johnson (Monsignor) on Jul 08, 2004 at 16:57 UTC
I have to say that I hate your use of the trinary operator there. You're expressing that you want to assign `die`'s result to `$file`. Instead: `my $file = $ARGV[0] or die "Usage: prog.pl file_pathname\n";` [download] (as a bonus, you don't have the redundant mention of `$ARGV[0]`). Better, if the filename might be zero: `@ARGV or die "Usage: prog.pl file_pathname\n"; my $file = $ARGV[0];` [download] We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply] [d/l] [select]