Beefy Boxes and Bandwidth Generously Provided by pair Networks
Do you know where your variables are?

Re^2: $1 not "freezing" in an addition

by ikegami (Pope)
on Dec 16, 2012 at 14:44 UTC ( #1009071=note: print w/replies, xml ) Need Help??

in reply to Re: $1 not "freezing" in an addition
in thread $1 not "freezing" in an addition

So your problem is that the recursive call to butter is evaluated before $1.

Quotes around $1 or using a subexpression like (0+$1) coerces Perl into changing the evaluation order,

Both of those statements are completely false. In all existing builds of Perl, the LHS of addition is always evaluated before it's RHS, so $1 is evaluated first in $1+f(). Keep in mind that $1 evaluates to a scalar, not a string. It's "+" that extracts the string from it, by which point the scalar's value has changed.

Study the following:

$_ = 3; print sub :lvalue { print "$_+"; $_ }->() + sub :lvalue { print "10="; ++$_; 10 }->(), "\n";

You can clearly see $_ being evaluated before 10 even though the value to which $_ is set by the RHS is used by the addition.

(Sorry for making a chain of post. I initially assumed your post was correct and that it just had a small problem, so I commented on it before reading on. And then the same thing happened another time. Only after that did I realize the entire post is wrong.)

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1009071]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others taking refuge in the Monastery: (7)
As of 2017-12-13 02:31 GMT
Find Nodes?
    Voting Booth?
    What programming language do you hate the most?

    Results (344 votes). Check out past polls.