Re: Check for existance in a hash of hashes

  DB<1> $a{foo}->{bar} = "zoikes"

  DB<2> print "yup\n" if exists $a{foo}
yup

  DB<3> print "yup\n" if exists $a{foo}->{bar}
yup

  DB<4> print "yup\n" if exists $a{foo}->{baz}

  DB<5> print "yup\n" if exists $a{foo} && exists $a{foo}->{bar}
yup

  DB<6> print "yup\n" if exists $a{foo} && exists $a{foo}->{baz}

  DB<7>
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Comment on Re: Check for existance in a hash of hashes Download Code

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Re2: Check for existence in a hash of hashes by dragonchild (Archbishop) on Mar 27, 2002 at 18:46 UTC
`$a{foo}{bar} = 'blah'; print "Yep\n" if exists $a{foo} && $a{foo}{bar}; print "Nope\n" if exists $a{bar}{baz}; print "Whoops!\n" if exists $a{bar};` [download] ------ We are the carpenters and bricklayers of the Information Age. Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.	[reply] [d/l]
Re: Re2: Check for existence in a hash of hashes by Fletch (Bishop) on Mar 27, 2002 at 18:51 UTC
You've created `$a{bar}` by your second check, just as `perldoc -f exists` explains. Although the deepest nested array or hash will not spring into existence just because its existence was tested, any intervening ones will. Thus "$ref->{"A"}" and "$ref->{"A"}->{"B"}" will spring into existence due to the existence test for the $key element above. This happens anywhere the arrow operator is used, including even:...	[reply] [d/l] [select]
Re4: Check for existence in a hash of hashes by dragonchild (Archbishop) on Mar 27, 2002 at 18:57 UTC
I know that. You know that. Did the original poster know that? Did all the readers of this thread know that? When you post a solution, you should post the common caveats, gimmes, and gotchas as well. Otherwise, those who may not be as fluent as the saints will get frustrated. ------ We are the carpenters and bricklayers of the Information Age. Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.	[reply]