Re^2: Does eval cause that much of a performance hit?

What are the alternatives:

my $foo;
if( $baz ) {
    $foo = $bar;
}
[download]

my $foo; 
$foo = $bar if $baz;
[download]

Of course, if you're setting $foo, then presumably your gonna use it at some point later. And unless your enamoured with testing every variable for undef prior to using it, then in most cases there is a sensible default that it can be initialised to. In which case:

my $foo = 0;
$foo = $bar if $baz;
[download]

Of course, that can be done "long hand" also if that's you preference.

And that's the point. Using this particular flaw in the Perl semantics as a justifiction for a style preference is disingenuous.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

Comment on Re^2: Does eval cause that much of a performance hit? Select or Download Code

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Re^3: Does eval cause that much of a performance hit? by grinder (Bishop) on May 06, 2009 at 13:38 UTC
What are the alternatives An alternative to your alternatives `my $foo = defined($baz) ? $bar : undef;` [download] or, with a sensible default, as an explicit undef is pretty dumb, `my $foo = defined($baz) ? $bar : 0;` [download] This saves at least a nextstate and an assignment, for no loss of readability. • another intruder with the mooring in the heart of the Perl	[reply] [d/l] [select]
Re^4: Does eval cause that much of a performance hit? by BrowserUk (Patriarch) on May 06, 2009 at 13:50 UTC
I agree with you, except that we've now moved so far from the OPs point: prefer things like a three line if construct than a trailing if., and perrin's response that we're almost on a different subject. 'sides which, the same people that eshew the trailing if also tend to reject the ternary as too complex/confusing/unclear/short. as an explicit undef is pretty dumb, I'm not sure where you saw the explicit undef? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^5: Does eval cause that much of a performance hit? by grinder (Bishop) on May 06, 2009 at 15:02 UTC
I don't think the topic has drifted. The point I wanted to make was that a ternary conditional is a viable alternative to introducing a scope (a 3-line if), if statement modifiers are not favoured by local shop practices. (Which is a reasonable edict, even if I don't agree with it myself). I'm not sure where you saw the explicit undef? There was none. It came about in my snippet from employing a ternary, which requires one to put something "in the else" part. • another intruder with the mooring in the heart of the Perl	[reply]
Re^3: Does eval cause that much of a performance hit? by perrin (Chancellor) on May 06, 2009 at 20:03 UTC
I was teasing. I use trailing if, although only in certain circumstances: it fits on one line without any obfuscation and it's an interrupt, like a next or return. But the flaw I pointed out with "my...if" is serious and scary and everyone should be aware of it.	[reply]
Re^4: Does eval cause that much of a performance hit? by BrowserUk (Patriarch) on May 06, 2009 at 20:22 UTC
I apologise for missing the humour. And you're right about "my..if".	[reply]


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