in reply to Re: How to no goto or gosub
in thread How to no goto or gosub

I'm curious. Every post has suggested either if (not $gas_cost < 1) or if ($gas_cost >= 1). Am I the only one who immediately thought unless ($gas_cost < 1)?

Do I just think strangely, or is unless too unclear for most people to consider using? (or is there some other reason for not using it?)

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Re^3: How to no goto or gosub
by choroba (Cardinal) on Jan 19, 2016 at 12:36 UTC
    The OP seemed as a beginner question to me. I tried not to introduce unnecessary details. On the other hand, I usually use unless in post-position only, to prevent an else from creeping in. 
    ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

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      Yeah, that makes sense :)

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Re^3: How to no goto or gosub
by shilo (Novice) on Jan 19, 2016 at 14:59 UTC

    I find that unless() has a very small useful footprint. Sure, may be OK when there is a single condition:

    unless ($things_went_wrong) { # do some stuff }

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    But, when there are multiple conditions, it gets tougher to keep straight: 

    unless ($result < $HIGHEST_VALUE && ! $bad_results{$result}) { # stuff
+ }

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    And then there is this legal, but almost much harder to follow, control structure: 

    unless ($result) {
    ## Do some stuff
}
elsif (!$result) {
    ## Do some other stuff
}
else {
    ## yet other stuff... 
}

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    In the end, 'unless(') is just a way to type 'if (!)', but with more keystrokes and it has a better chance of making your brain hurt. And, you never have to worry about decoding double negatives, or re-writing them if your control statements need to grow down the line if you just use 'if (!)'.

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      And then there is this legal, but almost much harder to follow, control structure:

      I've often wondered how many brains would explode if there was an unless ( ... ) { ... } elsless ( ... ) { ... } else { ... } construct in the language :-)

      Cheers,

      JohnGG

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      Yeah, I tend to stay away from elsif. Of course there are exceptions (aren't there always?), but I find that creating a logic flow that depends on lots of elsif calls just encourages people to continue expanding the structure long beyond the point it should have been refactored (case in point - one of our monolithic scripts has something like 30 or 40 chained elsif statements)

      Yes, I agree that unless has a small useful footprint, but I also think that if and elsif (especially the latter) are very easy to abuse.

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Re^3: How to no goto or gosub
by Anonymous Monk on Jan 19, 2016 at 09:15 UTC
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      Hmm, my personal opinion is that unless $condition is clearer than if !$condition and if $condition is clearer than unless !$condition. Horses for courses, I guess :)

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Re^3: How to no goto or gosub
by Discipulus (Canon) on Feb 05, 2016 at 21:44 UTC
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