Re: Shortcut operator for $a->{'b'}=$b if $b;

Something like

{ $a->{'b'} = do {$b or last} }
[download]

might abort the assignment if $b is not true. I can't test it at the moment. Another idea that occurs to me is

($a->{'b'} = $b) or delete $a->{'b'};
[download]

which expresses pretty directly what you said in your last sentence.

Caution: Contents may have been coded under pressure.

Comment on Re: Shortcut operator for $a->{'b'}=$b if $b; Select or Download Code

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Re^2: Shortcut operator for $a->{'b'}=$b if $b; by japhy (Canon) on Sep 20, 2005 at 16:54 UTC
I'd change the first one to simply: `{ $a->{b} = $b \|\| last }` [download] Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l]
Re^2: Shortcut operator for $a->{'b'}=$b if $b; by ikegami (Patriarch) on Sep 20, 2005 at 16:52 UTC
Tested. `last` does the trick.	[reply] [d/l]
Re^2: Shortcut operator for $a->{'b'}=$b if $b; by Aristotle (Chancellor) on Sep 20, 2005 at 20:35 UTC
It doesn’t “abort” the assignment – the logical OR is evaluated first, then possibly the `last`, and if that is evaluated, it prevents the assignment from evaluating at all. And thus it works. Makeshifts last the longest.	[reply] [d/l]
Re^3: Shortcut operator for $a->{'b'}=$b if $b; by CountZero (Bishop) on Sep 20, 2005 at 21:15 UTC
And thereby logical false values do not get assigned, which is not as per the specs. CountZero "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law	[reply]
Re^4: Shortcut operator for $a->{'b'}=$b if $b; by Roy Johnson (Monsignor) on Sep 20, 2005 at 22:21 UTC
You should re-read the OP's post. It says "The point is to have no key 'b' exist if $b is false." Caution: Contents may have been coded under pressure.	[reply]