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Re: Re: Re: Re: Test for standard input

by mikfire (Deacon)
on Oct 03, 2002 at 18:05 UTC ( #202597=note: print w/replies, xml ) Need Help??

in reply to Re: Re: Re: Test for standard input
in thread Test for standard input

Sorry, I cannot resist. Your code is ummmm doing lots of things that I do not think are what you intend.
$ARGS = @ARGV; if ( -t and $ARGS eq 0 ) { }
The more idiomatic way of saying this is
die "No input found\n" if ( -t and @ARGV == 0 );
I would also like to point out that you are testing the wrong kind of equality in your code -- you used the string equality test ( eq ) instead of the numeric test ( == ). In this case it worked, but it will someday drive you nuts trying to hunt this kind of bug down.

$names++, shift if $ARGV[0] eq "-l";
If I have figured this out correctly, you are trying to parse some command line options. I would strongly recommend using Getopt::Long, a core module that does this job very well.

I am assuming you really mean to shift the argument you just parsed out of @ARGV. Unfortunately, shift with no arguments assumes you mean @_, which is not @ARGV. Again, it likely works in this case, but I really doubt this is your intended affect.

The same holds true for the next line.

@ARGV = "-" unless @ARGV;
This code will never be executed. I am assuming it is a hold-over from your previous problems. The 'if' at the top of the program makes certain that @ARGV has to have something in it.

The assignment back to @ARGV is a little.... ugly IMHO. It took me several tries to figure out what it is doing. I would likely write this expression as

exit 0 unless ( grep { -T or $_ eq "-" } @ARGV );
but this is likely more a stylistic thing.

Oh, good use of the -w flag. It appears, though, you forgot to use strict. It will seem a pain at first, but it will really help as your programs get longer and more complex.


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Re: Re: Re: Re: Re: Test for standard input
by BUU (Prior) on Oct 03, 2002 at 23:57 UTC
    <pedantry>shift in a non subroutine context shifts from @ARGV.</pedantry>
      Damn. I have been programming perl for years now and I did not know this. Thanks!


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[choroba]: if you modify them, Perl will crash with "Modification of a read-only value attempted" for $1
[choroba]: I can't replicate the situation, but I remember it was very hard to debug

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