Beefy Boxes and Bandwidth Generously Provided by pair Networks
Keep It Simple, Stupid
 
PerlMonks  

Re^3: Bug in substitution operator?

by rhesa (Vicar)
on Jan 10, 2009 at 21:09 UTC ( #735432=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Bug in substitution operator?
in thread Bug in substitution operator?

update: my example went the wrong way. This is the issue:

use strict; my $v = 'x'; print qq"$v{a}"; __END__ xa
versus
use strict; my $v = 'x'; print qq{$v{a}}; __END__ Global symbol "%v" requires explicit package name at -e line 3.
I think the following quote from perlop under "Gory details of parsing quoted constructs" sheds some light on this quirk:

Note also that the interpolation code needs to make a decision on where the interpolated scalar ends. For instance, whether "a $b -> {c}" really means:
"a " . $b . " -> {c}";
or:
"a " . $b -> {c};
Most of the time, the longest possible text that does not include spaces between components and which contains matching braces or brackets. because the outcome may be determined by voting based on heuristic estimators, the result is not strictly predictable. Fortunately, itís usually correct for ambiguous cases.

I don't see this as a bug. Remember that the right-hand-side of s/// is just a double-quoted string, subject to the usual interpolation rules.

The same disambiguation is needed in regular interpolated strings. Consider this snippet:

use strict; my $var = "this"; print "$var{whatever}"; __END__ Global symbol "%var" requires explicit package name at -e line 3.
To fix the syntax error, and get the desired output, you do this:
use strict; my $var = "this"; print "${var}{whatever}"; __END__ this{whatever}


Comment on Re^3: Bug in substitution operator?
Select or Download Code
Re^4: Bug in substitution operator?
by polettix (Vicar) on Jan 10, 2009 at 23:10 UTC
    I get the same error in both examples:
    use strict; my $v = 'x'; print qq"$v{a}"; __END__ Global symbol "%v" requires explicit package name at rhesa1.pl line 3. Execution of rhesa1.pl aborted due to compilation errors.
    I agree that the attention should be moved to double quotes, anyway. This gives the very same error as above:
    use strict; my $v = 'x'; print qq{$v\{a\}}; __END__ Global symbol "%v" requires explicit package name at rhesa3.pl line 3. Execution of rhesa3.pl aborted due to compilation errors.
    while this doesn't:
    use strict; my $v = 'x'; print "$v\{a\}"; __END__ x{a}
    I'm not convinced that it'is an incarnation of the problem described in the documentation, anyway: in our case we have a different behaviour in the very same string when the double-quoted string is delimited with different characters, which is not what's discussed in the docs.

    perl -ple'$_=reverse' <<<ti.xittelop@oivalf

    Io ho capito... ma tu che hai detto?

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://735432]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others cooling their heels in the Monastery: (9)
As of 2014-07-22 22:03 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    My favorite superfluous repetitious redundant duplicative phrase is:









    Results (129 votes), past polls