Re: How do I use a block as an ‘or’ clause instead of a simple die?

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Re^2: How do I use a block as an ‘or’ clause instead of a simple die? by ikegami (Patriarch) on Apr 18, 2009 at 17:35 UTC
The limit of `if` is encountered if you declare a variable. `if (!open(my $fh, '<', $qfn)) { ... } print $fh $s; # XXX` [download] `if (my ($y) = f($x)) { # Returns () on error. ... } print defined($y) ? $y : '[undef]'; # XXX` [download] Solutions: Declare the var earlier: `my $fh; if (!open($fh, '<', $qfn)) { ... }` [download] `my $y; if (($y) = f($x)) { # Returns () on error. ... }` [download] Save the result: `my $success = open(my $fh, '<', $qfn); if (!$success) { ... }` [download] `my $success = my ($y) = f($x); # Returns () on error. if (!$success) { ... }` [download] Use `do`: `open(my $fh, '<', $qfn) or do { ... };` [download] `my ($y) = f($x) # Returns () on error. or do { ... };` [download]	[reply] [d/l] [select]

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if

if (!open(my $fh, '<', $qfn)) {
   ...
}

print $fh $s;  # XXX
[download]

if (my ($y) = f($x)) {   # Returns () on error.
   ...
}

print defined($y) ? $y : '[undef]';  # XXX
[download]

Solutions:

Declare the var earlier:

my $fh;
if (!open($fh, '<', $qfn)) {
   ...
}
[download]

my $y;
if (($y) = f($x)) {   # Returns () on error.
   ...
}
[download]

Save the result:

my $success = open(my $fh, '<', $qfn);
if (!$success) {
   ...
}
[download]

my $success = my ($y) = f($x);  # Returns () on error.
if (!$success) {
   ...
}
[download]

Use do:

open(my $fh, '<', $qfn)
   or do { ...
         };
[download]

my ($y) = f($x)   # Returns () on error.
   or do { ...
         };
[download]