in reply to Re: Re: Re: OR operator
in thread OR operator

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(jeffa) 5Re: OR operator
by jeffa (Bishop) on Apr 10, 2003 at 21:15 UTC
    I fail to see the big deal in using $_ on the left or the right. I mean, tomAYto tomAHto. Where i see people making a big deal about this is with code that uses the numerical comparison operator, which can easily be mistyped, yielding an assignment operator: 
    perl -le'print "Yep" if $_ = 42'

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    Switch the two operands and you get a syntax error: 
    perl -le'print "Yep" if 42 = $_'

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    Me? I still use the former, because if i make that mistake i want to be punished ;) ... but i can definitely see recommending the later to someone else. But ... as for 'readabilty', i say use whichever makes the most sense to the author.

    Is today's date April 10th or the 10th of April? ;)

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
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Re: Re: Re: Re: Re: OR operator
by DrManhattan (Chaplain) on Apr 10, 2003 at 17:13 UTC
    I think we're actually on the same page here. In my mind, $color is "this thing" and $_ is e.g. "blue". The code asks, "Is $color red", "Is $color green", or "Is $color blue?" To me, $_ eq $color reads, "Is red $color", "Is blue $color", or "Is green $color?" which seems backwards.

    -Matt

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      I think we're actually on the same page here. In my mind, $color is "this thing" and $_ is e.g. "blue".

      But "for" topicalizes. $_ is the topic. $_ is more variable than $color, $_ is the thing. 

      for (qw/green blue red/) {
    if ($color eq $_) { ... }
}

for each of green, blue and red:
    if the color is it, do something

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      for (qw/green blue red/) {
    if ($_ eq $color) { ... }
}

for each of green, blue and red:
    if it is the color, do something

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      I read $_ as "the thing" or "it". How do you read $_?

      Juerd
- http://juerd.nl/
- spamcollector_perlmonks@juerd.nl (do not use).

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        I read $_ as "the thing" or "it". How do you read $_?

        The original poster wanted this: 

        if ($color eq "blue || $color eq "red" || $color eq "green")

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        My second post essentially stated ... 
        if ($color eq $_)

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        ... and dynamically replaced $_ with "blue", "red", or "green". Thus to me, $_ eq $color is like stating ... 
        if ("blue eq $color || "red" eq $color || "green" eq $color)

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        ... which isn't intuitive.

        -Matt

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