Re: Annoying warnings...

( reftype $x or '' ) eq 'HASH'
Has any of you, by any chance, found a more clueful approach to dealing with these annoying warnings?

Ugg — that's ugly, and quite obfuscated: it isn't apparent from glancing at that code exactly what it does or that it's written like that to avoid a warning. Creating a new block with that particular warning disabled at least has the advantage of making it absolutely clear what you're doing.

A clearer way of doing the above without a block is simply to test $x for being true (since all refs are true) first — this avoids the mysterious empty string constant and translates quite well into the equivalent English:

$x && reftype $x eq 'HASH'

(By the way I think it's slightly insulting of you to ask if any of us have suggestions for this "by any chance" — implying that we only discover things randomly rather than through having intelligence or talent!)

Smylers

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Re^2: Annoying warnings... by adrianh (Chancellor) on Jul 16, 2005 at 14:51 UTC
Ugg — that's ugly, and quite obfuscated: it isn't apparent from glancing at that code exactly what it does or that it's written like that to avoid a warning I disagree. That's a common idiomatic way of resolving the problem of false/undef in some expressions and I see it in lots of code. The only problem with this strategy is that it sometimes gets used in places where non-undef false values like '0' shouldn't be ignored, which can lead to odd bugs. Not a problem in this instance. `$x && reftype $x eq 'HASH'` As already pointed out this breaks for true non-reference values. In this particular instance I'd probably make it a bit more explicit the exact thing I'm looking for: `# I want a reference whose type is 'HASH' ref $x && reftype $x eq 'HASH';` [download]	[reply] [d/l] [select]
Re^2: Annoying warnings... by tlm (Prior) on Jul 16, 2005 at 13:07 UTC
A clearer way of doing the above without a block is simply to test $x for being true (since all refs are true) first... Well, not quite. The code you proposed would still result in a warning if `$x` is 1, for example: `% perl -MScalar::Util=reftype -we '$x=1; my $y=($x and reftype $x eq q +(HASH))' Use of uninitialized value in string eq at -e line 1.` [download] What needs to be tested is that the value returned by `reftype $x` is defined. So your solution should be cast as `...( reftype $x and reftype $x eq 'HASH' )...` [download] or, two avoid the duplicate calls to `reftype`: `{ my $temporary_variable = reftype $x; ...( $temporary_variable and $temporary_variable eq 'HASH' )... }` [download] Update: Fixed missing `"$x and "` in the one-liner. the lowliest monk	[reply] [d/l] [select]