Re^2: Test Number of Elements In Array

I use it all the time now by habit, and I never have to worry about accidentally assigning instead of comparing.

The downsite is having "magic" numbers in your source code. And the trick only works when comparing against a literal, not a variable. If you write:

my $SPECIAL_SIZE = 10;
...
if ($SPECIAL_SIZE == @array) {
   ...
}
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and you mistype '=' instead of '==', you're out of luck again. Now, using use constant SPECIAL_SIZE => 10; will save you, but constants defined that way aren't easy to interpolate.

As usual with programming, doing X to avoid Y compromises on Z. Personally, I prefer not having 'magic numbers' in my source code, relying on test cases to avoid the '=' typo.

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Re^3: Test Number of Elements In Array by liverpole (Monsignor) on Jun 07, 2009 at 15:45 UTC
"The downsite is having "magic" numbers in your source code." One doesn't introduce any new "magic numbers", if instead of writing: `if (@wishes == 3) { print "The genie has granted all of your wishes\n"; }` [download] One writes: `if (3 == @wishes) { print "The genie has granted all of your wishes\n"; }` [download] "And the trick only works when comparing against a literal, not a variable." Granted. But that doesn't make it any less useful to use for constants, which was my point. Speaking of magic numbers, I think one can get too carried away with their usage. I would argue the following goes a bit overboard ... `my $days_per_year = 365; # In case the number of days in a year chang +es ;-) ... if (@calendar < $days_per_year) { warn "Hold on, Cinderella -- you're calendar isn't full yet.\n"; }` [download] The above example is based on a college classmate of mine who, back in the days of BASIC, had the constant "dpy" ("Days per year") in a startup script, so when he needed it, he could type "dpy" instead of "365"! s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/	[reply] [d/l] [select]
Re^4: Test Number of Elements In Array by akho (Hermit) on Jun 07, 2009 at 15:58 UTC
It's buggy no matter if you use a constant or not. Last year had 366 days. Things change even when you don't expect them to.	[reply]