Re^4: Compiler Optimization

You're giving the optimiser too much credit

Ok ... and I'm somewhat relieved about that :-)
But can ($var || 2) ever be false ?

The code provided initially by the OP was:

if ($var || 2) {
    # do stuff here
}
else {
    # won't do stuff 
}
[download]

If ($var || 2) is inevitably true, then that code is a rather silly (even obfuscating) construct.
All that was really needed was:

$var || 2;
# do stuff here
[download]

or simply:

$var;
# do stuff here
[download]

Is it safe for the OP to make such alterations, or do I overlook something ?
Afterthought: I'm actually now wondering whether the original code was in fact ($var | 2) and not ($var || 2)

Cheers,
Rob

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Re^5: Compiler Optimization by BrowserUk (Patriarch) on Feb 25, 2015 at 02:42 UTC
But can ($var \|\| 2) ever be false ? No way I can see. So yes, the OPs code should be reducible to just `$var;` though that will produce a warning: `Useless use of private variable in void context ...`. And `$var \|\| 2;` gets `Useless use of a constant in void context ...` Replace the 2 with 1: `$var \|\| 1;` to take advantage of a special case that produces no warning and deparses as: `C:\Users\HomeAdmin>perl -MO=Deparse -Mstrict -wle"my $var = 1; $var \|\| + 1;" BEGIN { $^W = 1; } BEGIN { $/ = "\n"; $\ = "\n"; } use strict 'refs'; my $var = 1; '???' unless $var; -e syntax OK` [download] Or: `1 if $var;` [download] which achieves the same thing. Or, if he's happy there are no ties involved, ditch the whole darn thing. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' 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". I'm with torvalds on this In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked	[reply] [d/l] [select]

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Re^5: Compiler Optimization
by BrowserUk (Patriarch) on Feb 25, 2015 at 02:42 UTC

But can ($var || 2) ever be false ?

No way I can see. So yes, the OPs code should be reducible to just $var; though that will produce a warning: Useless use of private variable in void context ....

And $var || 2; gets Useless use of a constant in void context ...

Replace the 2 with 1: $var || 1; to take advantage of a special case that produces no warning and deparses as:

C:\Users\HomeAdmin>perl -MO=Deparse -Mstrict -wle"my $var = 1; $var ||
+ 1;"
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict 'refs';
my $var = 1;
'???' unless $var;
-e syntax OK
[download]

Or:

1 if $var;
[download]

which achieves the same thing.

Or, if he's happy there are no ties involved, ditch the whole darn thing.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

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". I'm with torvalds on this

In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked

[reply]
[d/l]
[select]