[25797] in Perl-Users-Digest
Perl-Users Digest, Issue: 8036 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Sun May 1 14:05:28 2005
Date: Sun, 1 May 2005 11:05:08 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Sun, 1 May 2005 Volume: 10 Number: 8036
Today's topics:
Re: Looking for Perl Grammar <khamis@wellcode.com>
Re: Looking for Perl Grammar <pilkowsk@informatik.uni-marburg.de>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Sun, 01 May 2005 13:41:23 +0200
From: Khamis Abuelkomboz <khamis@wellcode.com>
Subject: Re: Looking for Perl Grammar
Message-Id: <d52f8u$52d$04$1@news.t-online.com>
Fabian Pilkowski wrote:
> * Khamis Abuelkomboz schrieb:
>
>>However I still find clauses like
>>
>>if ( s{foo}{bar} ) ...
>>if ( s[foo][var] ) ...
>>if ( s<foo><bar> ) ...
>>
>>I still don't figure out what could be used as "brackets" for the
>>s|tr|m commands???? So I'm looking as example for grammar descriping
>>how the (s, tr, qq) could be built, something like
>>
>>S: s OP1 expr OP2 expr OP3
>>OP1: '/' | '{' | '[' | ':' | ...
>>OP2: '/' | '}{' | '][' | ...
>>OP3: '/' | '}' | ']' | ':' | ...
>>
>>I'm still guissing :-)
>
>
> This is mentioned in `perldoc perlop` in the section named "Quote and
> Quote-like Operators".
>
> Non-bracketing delimiters use the same character fore and aft, but
> the four sorts of brackets (round, angle, square, curly) will all
> nest, which means that
>
> q{foo{bar}baz}
>
> is the same as
>
> 'foo{bar}baz'
>
> [...]
>
> There can be whitespace between the operator and the quoting
> characters, except when # is being used as the quoting character.
> q#foo# is parsed as the string foo, while q #foo# is the operator q
> followed by a comment. Its argument will be taken from the next
> line. This allows you to write:
>
> s {foo} # Replace foo
> {bar} # with bar.
>
> So, for s/// you could start with a grammar similar to
>
> S: s WS BRACKETED WS BRACKETED | s WS DELIM expr DELIM expr DELIM
> BRACKETED: '(' expr ')' | '<' expr '>' | '[' expr ']' | '{' expr '}'
> WS: WHITE-SPACES *
> DELIM: '/' | '!' | ':' | '^'
>
> I'm not deeply familiar with grammar descriptions. Is there a way to
> ensure that each DELIM is the same char?
>
> Don't forget to add the special behavior of »#« to your grammar. And of
> course, do you want to allow comments between the BRACKETED parts as in
> the example above? ;-)
>
> regards,
> fabian
Hello!
Thank you all for your input. I still have a question, I found something like:
local $SIG{__DIE__} = sub {};
local $SIG{__WARN__} = sub {};
What does it mean? Does it define two local variables or two elements of an array? What does "sub
{}" here meen?
I thougt, (my|local|our) declare variables without those nasty brackets!
thanks
khamis
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------------------------------
Date: Sun, 1 May 2005 14:23:53 +0200
From: Fabian Pilkowski <pilkowsk@informatik.uni-marburg.de>
Subject: Re: Looking for Perl Grammar
Message-Id: <3dk022F6ur5olU1@individual.net>
* Khamis Abuelkomboz schrieb:
>
> Thank you all for your input. I still have a question, I found something like:
>
> local $SIG{__DIE__} = sub {};
> local $SIG{__WARN__} = sub {};
>
> What does it mean? Does it define two local variables or two elements
> of an array? What does "sub {}" here meen?
In Perl, there is a global hash called %SIG (see `perldoc perlvar` to
learn what it is for). Here, you want to localize the elements __DIE__
and __WARN__ (see `perldoc -f local`). The »sub« actually returns a code
ref of the closure (anonymous sub) you just created. In this case, the
closure is empty.
regards,
fabian
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 8036
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