LPM: H*lp with undef?

[Mik Firestone]

$in{' '} = '';			# Init your constant

$some_field = $in{"myfield"} || ' ';				# Line 51
$foo 	   = "Their field has: " . $in{$some_field};		# Line 52

should take care of this problem.  Yes, the purists will likely object.


HTH,
  Mik
On Thu, 18 Nov 1999, David Hempy wrote:

> 
> Okay, I'm a bit stumped here regarding very simple use of a hash.  I want
> to say:
> 
> 	$some_field = $in{"myfield"};				# Line 51
> 	$foo = "Their field has: " . $in{$some_field};		# Line 52
> 
> Problem is, if there is no $in{"myfield"}, then $some_field is undef, and I
> get:
> 
> 	"Use of uninitialized value at mailform.bat line 52."
> 
> I do not know in advance whether there will be "myfield" or not...it is
> optional.  I had expected the . operator to quietly ignore my attempt to
> concatenate a string and undef, as that seems like a pretty perlish sort of
> thing from what I've seen.  
> 
> I *think* the problem is trying to use . and undef together...I don't think
> searching for an undef key in the hash is the problem, but I'm not crystal
> clear on that one.
> 
> 
> 
> The cleanest solution I've come across so far is:
> 
> 	$foo = "Their field has: " . $in{$some_field} if defined($some_field);
> 
> This still seems pretty cludgey, and not nearly as graceful as the scripts
> Rich and Nat share with us.  There are a dozen places I use optional fields
> in this CGI script, and would much rather just use them blindly regardless
> of whether they are undef or not, instead of testing their values all over
> the place.
> 
> Can I change the assignment of $some_field so it gets a more benign value
> that won't cause errors later on and won't require testing?
> 
> 
> Am I missing something here?  Am I trying to push a rope up a hill?  Any
> suggestions?
> 
> 
> -dave
> 
> 
> 
> --
> David Hempy
> Internet Database Administrator
> Kentucky Educational Television
> 
> 


-- 
Mik Firestone fireston at lexmark.com
When I become an Evil Overlord:
I will be secure in my superiority. Therefore, I will feel no need to prove it
by leaving clues in the form of riddles or leaving my weaker enemies alive to
show they pose no threat.