A question about regexp

ruby-talk
1

Hi,

I’m trying to make the following code works but I don’t know how…

···

def mygrep( exp )
ar = [ “element1”, “element2” ]
ar.grep( exp ) { |e|
# works…
print "grep: #$&\n"
yield e
}
end

mygrep( /(.*)/ ) { |e|

doesn’t work…

print “mygrep: #$&\n”
}

Displaying $& in the inner loop of grep works fine, but when it enter my own
block, $& is put back to nil. Is there a way to keep the value of $& (and
all others $1…)?

Thankx,
Ben.

2

Displaying $& in the inner loop of grep works fine, but when it enter my own
block, $& is put back to nil. Is there a way to keep the value of $& (and
all others $1...)?

Well, $~ is a local, and thread local variable and perhaps in your case it
best to give this variable to the block, something like

   def mygrep( exp )
      ar = [ "element1", "element2" ]
      ar.grep( exp ) { |e|
         yield e, $~
      }
   end

   mygrep( /(.*)/ ) { |e, match|
      # doesn't work...
      print "mygrep: #{match[0]}\n"
   }

$~ is an object MatchData

pigeon% ri MatchData

···

------------------------------------------------------------------------
     class: MatchData
------------------------------------------------------------------------
     MatchData is the type of the special variable $~, and is the type
     of the object returned by Regexp#match and Regexp#last_match. It
     encapsulates all the results of a pattern match, results normally
     accessed through the special variables $&, $', $`, $1, $2, and so
     on.

------------------------------------------------------------------------
     , begin, end, length, offset, post_match, pre_match, size,
     string, to_a, to_s
------------------------------------------------------------------------
pigeon%

Guy Decoux

3

I’d say it should read

def mygrep( exp )
ar = [ “element1”, “element2” ]
ar.grep( exp ) { |e|
# works…
print “grep: #$&\n”
yield e
}
end

mygrep( /(.*)/ ) { |e|

does work now

print “mygrep: #{e}\n”
}

I would not have the block rely on some global var being set.

robert

“Ben Thomas” ben.thomas@wickedstudios.com schrieb im Newsbeitrag
news:_4hka.1431$u13.938880113@news.nnrp.ca…

Hi,

I’m trying to make the following code works but I don’t know how…

def mygrep( exp )
ar = [ “element1”, “element2” ]
ar.grep( exp ) { |e|
# works…
print “grep: #$&\n”
yield e
}
end

mygrep( /(.*)/ ) { |e|

doesn’t work…

print “mygrep: #$&\n”
}

Displaying $& in the inner loop of grep works fine, but when it enter my
own
block, $& is put back to nil. Is there a way to keep the value of $&
(and

···

all others $1…)?

Thankx,
Ben.

4

Hi,

···

At Tue, 8 Apr 2003 01:06:20 +0900, ts wrote:

Displaying $& in the inner loop of grep works fine, but when it enter my own
block, $& is put back to nil. Is there a way to keep the value of $& (and
all others $1…)?

Well, $~ is a local, and thread local variable and perhaps in your case it
best to give this variable to the block, something like

You can assign a MatchData to $~ and use $& and so on, but I
don’t recommend it.

–
Nobu Nakada