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

I assume you mean $b is a long expression, so you'd rather avoid having it twice. If so, you could topicalize $b:

{
   local $_ = $b;
   $a->{b} = $_ if defined $_;
}
[download]

or (update)

$a->{b} = $_ foreach grep defined, $b;
[download]

or you could add everything then remove undefined values:

delete @$a{ grep { not defined $a->{$_} } keys %$a };
[download]

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

Replies are listed 'Best First'.
Re^2: Shortcut operator for $a->{'b'}=$b if $b; by rokadave (Sexton) on Sep 20, 2005 at 16:27 UTC
Yes. If there's no shortcut operator, then your suggestion is the cleanest it'll get. I was hoping there existed an "assign-if-true" operator.	[reply]
Re^3: Shortcut operator for $a->{'b'}=$b if $b; by ikegami (Patriarch) on Sep 20, 2005 at 16:32 UTC
You could write the operator yourself: `sub assign_if_defined { $_[0] = $_[1] if defined $_[1]; } assign_if_defined($a->{'b'}, $b);` [download] By the way, I'm using `defined` since you said you didn't want empty keys. Checking for truthfullness (as you have been doing) removes both empty and false keys. Just remove the word `defined` for a truth test.	[reply] [d/l] [select]
Re^4: Shortcut operator for $a->{'b'}=$b if $b; by leriksen (Curate) on Sep 21, 2005 at 03:24 UTC
Maybe someone can suggest how to define a '?=' operator `$a->{'b'} ?= $b;` assigns $b to $a->{'b'} if $b is defined, does not autovivify $a->{'b'} if $b not defined is that possible? - I'm thinking of `use overload` but I dimly recall that there is a finite set of operators you can overload and ?= isnt one of them. ...reality must take precedence over public relations, for nature cannot be fooled. - R P Feynmann	[reply] [d/l] [select]
Re^5: Shortcut operator for $a->{'b'}=$b if $b; by ikegami (Patriarch) on Sep 21, 2005 at 05:28 UTC


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