Re: Defining Characters in Word Boundary?

is it possible to define the characters that '\b' matches? I am processing latex code, and their macro character space is \ a-zA-Z \. I would like to write

\\$keyword\b

Unless I'm understanding your intentions wrong, that's the purpose of \b.

Example: m/\bChi_2\b/

I don't think the underscore will cause you problems within the defined \b \b but I'm sure I'll be corrected shortly if I'm wrong. :)

Through help in the chatterbox and "Mastering Regular Expressions" pg. 89, I learned that \w has included _ since Perl 2. So /\bChi_2\b/ will not match.

"...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote

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Re^2: Defining Characters in Word Boundary? by ikegami (Patriarch) on Jan 19, 2011 at 23:17 UTC
I believe he's saying that "`_2`" isn't part of the macro, so `$keyword = 'Chi'; '...\\Chi_2...' =~ /\\$keyword\b/` should match.	[reply] [d/l] [select]
Re^3: Defining Characters in Word Boundary? by luis.roca (Deacon) on Jan 19, 2011 at 23:39 UTC
Ugh! — Apologies to the OP. I misread that. "...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote	[reply]
Re^2: Defining Characters in Word Boundary? by ikegami (Patriarch) on Jan 21, 2011 at 01:42 UTC
I'm not sure why you added the update. I don't see what it adds, and it's not true. `/\bChi_2\b/` will match plenty of strings. `'Chi_2' =~ /\bChi_2\b/ # Match '!Chi_2!' =~ /\bChi_2\b/ # Match` [download] Maybe you had a specific string in mind, but I don't see how this relates to the OP. He would not use `Chi_2` in the regex pattern. In a world where an identifier matches `/^\w+\z/`, you might do something like `($_ = '\\Chi+3' ) =~ s/\\Ch\b/$ch/g; # Won't replace ($_ = '\\Chi+3' ) =~ s/\\Chi\b/$chi/g; # Will replace ($_ = '\\Chi_2+3') =~ s/\\Chi\b/$chi/g; # Won't replace` [download] But what if identifiers match `/^[a-zA-Z]\z/`? You'd want the following behaviour: `($_ = '\\Chi+3' ) =~ s/\\Ch???/$ch/g; # Won't replace ($_ = '\\Chi+3' ) =~ s/\\Chi???/$chi/g; # Will replace ($_ = '\\Chi_2+3') =~ s/\\Chi???/$chi/g; # Will replace` [download] That's the OP's question. As I've already mentioned, I recommend extracting the identifier, then checking if it's one of interest. This can be as simple as the following: `/\\([a-zA-Z]+)/ exists($vars{$1}) ? $vars{$1} : "\\$1" /eg` [download] The technique scales well, and it avoids the problem of matching something you've previously replaced.	[reply] [d/l] [select]
Re^3: Defining Characters in Word Boundary? by luis.roca (Deacon) on Jan 21, 2011 at 04:45 UTC
"Maybe you had a specific string in mind, but I don't see how this relates to the OP. He would not use Chi_2 in the regex pattern. I did have a very similar string in mind. In a world where an identifier matches /^\w+\z/, you might do something like" `($_ = '\\Chi_2+3') =~ s/\\Chi\b/$chi/g; # Won't replace` I understand my update isn't contributing to the OP's original question. I'm not trying to distract from his post or the thread, simply attempting to correct what I said regarding the underscore having no effect on the RegEx's success (again the one I had in mind). In my original reply I was referring to matching 'Chi' within 'Chi_2' using \b. I previously said that I didn't think the underscore would be a problem. However after some help in the CB from erix and Tanktalus it was shown that an underscore would interfere with this particular match: `say (("Chi_2" =~ /\bChi\b/) ? "match" : "no match");` returns: "no match" * Thanks again to Tantalus for this control structure. Again, apologies for any confusion caused. "...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote	[reply] [d/l] [select]
Re^4: Defining Characters in Word Boundary? by ikegami (Patriarch) on Jan 21, 2011 at 07:12 UTC
In my original reply I was referring to matching 'Chi' within 'Chi_2' using \b So you meant `/\bChi\b/` wouldn't match. That makes more sense.	[reply] [d/l]