Re: Declare my variable in sysread

It's the same trick as in

while (my $line = <$fh>) {
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which is a shorthand for

while (defined( my $line = readline($fh) )) {
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where, again, my $line appears as an ~~argument~~ operand of = which in turn is an ~~argument~~ operand of defined. my has two effects, one compile time and one run time. In compile time, you declare a lexical variable, and in runtime, you use it as an lvalue (i.e. assign a value to it). Variables declared in block conditions (if, while, unless, until) are accessible until the last conditional operator block.

if (my $x = func()) {
    print "$x accesible here";
} elsif ($x eq 0) { # even here,
   print "and also here: $x";
}
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Updated.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

Comment on Re: Declare my variable in sysread - Mojo::File::slurp Select or Download Code

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Re^2: Declare my variable in sysread - Mojo::File::slurp by ikegami (Patriarch) on Dec 22, 2018 at 00:43 UTC
my $line appears as an argument of defined. No, it doesn't. It's an operand of `=`, not `defined`.	[reply] [d/l] [select]
Re^3: Declare my variable in sysread - Mojo::File::slurp by choroba (Cardinal) on Dec 22, 2018 at 00:46 UTC
But the = is, in turn, an ~~argument~~ operand to defined. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re^4: Declare my variable in sysread - Mojo::File::slurp by ikegami (Patriarch) on Dec 22, 2018 at 00:56 UTC
Yes, `=` is an operand of `defined`, but your whole point is that `sysread($file, my $buf, ...)` is like `defined(my $line)`, but your code doesn't use `defined(my $line)`.	[reply] [d/l] [select]
Re^2: Declare my variable in sysread - Mojo::File::slurp by ikegami (Patriarch) on Dec 22, 2018 at 00:52 UTC
my $line appears as an argument of = which in turn is an argument of defined. You're still claiming `my $line` is an argument of `defined`, and it's not. Operators have operands (not arguments), and the variable `$line` is `defined`'s operand.	[reply] [d/l] [select]