what is "}{"?

[zenny lenny]

I DID check the FAQ first.

Two questions:

1. This code adds a column of numbers: perl -lne '$x+=$_}{print $x;'

What is the purpose of "}{"?

2. Is there any way to search groups or the web for symbols like "}
{"? Google seems to ignore symbols like this.

 

[Brian McCauley]

I DID check the FAQ first.

Two questions:

1. This code adds a column of numbers: perl -lne '$x+=$_}{print $x;'

What is the purpose of "}{"?

It is the end of one block (executed once per line) and the start of
another block (executed once).

It makes sense if you know what -n actually does.

The above is simply short for:

2. Is there any way to search groups or the web for symbols like "}
{"?

Not that I know of.

However you could perhaps grep the Perl manual - this trick may be
mentioned in there somewhere.

 

[Klaus]

1. This code adds a column of numbers: perl -lne '$x+=$_}{print $x;'
What is the purpose of "}{"?

You are using "-n" in a very clever way indeed:

perldoc perlrun:
....so with '$x+=$_}{print $x;'
your program will be...

LINE:
while (<>) {
$x+=$_}{print $x;
}

....or reformatted...

LINE:
while (<>) {
$x+=$_
}
{ print $x; }

-- Klaus

 

[Michele Dondi]

You are using "-n" in a very clever way indeed:

s/You are/Someone is/; #


Michele

 

[Michele Dondi]

Subject: what is "}{"?

Michele

 

[Wade Ward]

Heh, that's intentional obfuscation. Abigail explains it
here (see the "Counting Lines" section):

http://ucan.foad.org/~abigail/Perl/Talks/Japhs/

The -n switch (see 'perldoc perlrun') wraps your
code, similar to -p but without the continue and
print portion.

You can also use a module to make things clearer:

$ perl -MO=Deparse -nle '$x+=$_}{print $x;'

BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = <ARGV>)) {
chomp $_;
$x += $_;
}
{
print $x;
}
-e syntax OK

Aren't they just curly braces that are guaranteed to be unmatched? A google
search would hit every entry that has two or more sets of curly braces.

 

[Dr.Ruud]

zenny lenny schreef:

1. This code adds a column of numbers: perl -lne '$x+=$_}{print $x;'

What is the purpose of "}{"?

Try -MO=Deparse like this:

perl -MO=Deparse -ne'$x+=$_}{print $x'

 

[Michele Dondi]

== What is the purpose of "}{"?
==


Self reflection. Do you see a vase, or two faces looking at each other?

A yo-yo. With no string.


Michele