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Re^3: capture vars undef

by Chady (Priest)
on Jul 28, 2004 at 06:20 UTC ( #377937=note: print w/ replies, xml ) Need Help??

in reply to Re^2: capture vars undef
in thread capture vars undef

They haven't gone out of scope. Here's an attempt at explaining that:

In the first example, you have two if blocks, the first if block provides a new scope for the second block, so what you have is something like this:

# provided by the outermost if $1 = undef; $2 = undef; $3 = undef; { # provided by the inner if $1 = 'aa'; $2 = 'bb'; $3 = 'cc'; }

Note that one if block will not kill the $<digit> vars, but once the inner block finishes, then its variables are destroyed, and you get the outer block's $<digit>s

Here's an example that might explain it better:

$_ = "aabbccdd"; if ( /^(\w\w)\w\w(\w\w)\w\w$/ ) { if ( /^\w\w(\w\w)\w\w(\w\w)$/ ) { print "inner: $1 $2\n"; } print "mid: $1 $2\n"; # the inner if's vars are still accessible h +ere } print "outer: $1 $2\n";

This will print aa cc and not your expected bb dd in the outer block.

Update: here's another way to think of it:

$_ = "aabbccdd"; /^(\w\w)\w\w(\w\w)\w\w$/; { /^\w\w(\w\w)\w\w(\w\w)$/; { print "inner: $1 $2\n"; } print "mid: $1 $2\n"; } print "outer: $1 $2\n";

He who asks will be a fool for five minutes, but he who doesn't ask will remain a fool for life.

Chady |

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