I would guess there's some basic string or regex syntax that I'm missing
here. I've looked at the gsub and string documentation, and either I
missed it or I should be looking elsewhere.
Can someone give me a clue and help me move forward with my mother's day
hacking session?
I would guess there's some basic string or regex syntax that I'm missing
here.
In double quoted strings escaped characters do not have literal
meanings. For instance, in a double quoted string "\n" is not two
characters--it is one character that represents a newline. Double
quoted strings interpret all escaped characters, which means that \1
gets interpreted into something( but who knows what!).
On the other hand, with single quoted strings there are only a couple of
automatic substitutions that take place, and interpreting \1 is not one
of them. So with single quoted strings \1 means \1.
If you need to use double quoted strings, then you need to literally
have \1 in your string, which requires the use of additional backslashes
to escape the \ in "\1". So try "\\1". With ruby if one backslash is
not enough, keep adding more backslashes until whatever you are trying
accomplish works!
If you need to use double quoted strings, then you need to literally
have \1 in your string, which requires the use of additional backslashes
to escape the \ in "\1". So try "\\1". With ruby if one backslash is
not enough, keep adding more backslashes until whatever you are trying
accomplish works!
That does not work as 7stud did not mention the most important point: even with proper escaping this won't work as the string interpolation takes place *before* gsub is invoked and hence URI.escape will insert something but not the matched portion. In your tests it has probably worked because $2 was properly set from the previous match.
Whether this is something you want or not depends on you but AFAIK mixing quote types is not allowed here so we probably rather not want to do the replacement in that case.
Note that my regexp has another weakness: the quote character not used to quote the URI should be allowed as part of the URI. I did not want to complicate things too much but if you want to deal with this the regular expression must be made a bit more complex.
Kind regards
robert
···
On 11.05.2009 02:18, Sarah Allen wrote:
7stud -- wrote:
If you need to use double quoted strings, then you need to literally have \1 in your string, which requires the use of additional backslashes to escape the \ in "\1". So try "\\1". With ruby if one backslash is not enough, keep adding more backslashes until whatever you are trying accomplish works!
even with proper escaping this won't work as the string interpolation
takes place *before* gsub is invoked and hence URI.escape will insert
something but not the matched portion. In your tests it has probably
worked because $2 was properly set from the previous match.
really? so the ${...} gets evaluated before the param is passed to gsub,
but the block is passed as code, so then it is evaluated after.
Using the previous attempt, with a fresh irb session, I can see the
issue:
NoMethodError: private method `gsub' called for nil:NilClass
from
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/uri/common.rb:289:in
`escape'
from (irb):8
Note that my regexp has another weakness: the quote character not used
to quote the URI should be allowed as part of the URI. I did not want
to complicate things too much but if you want to deal with this the
regular expression must be made a bit more complex.
Wow, interesting. That would be incorrect HTML that the browser doesn't
deal with well, so I'll not worry about it for this case, but I would be
curious how it might be handled.
even with proper escaping this won't work as the string interpolation
takes place *before* gsub is invoked and hence URI.escape will insert
something but not the matched portion. In your tests it has probably
worked because $2 was properly set from the previous match.
really? so the ${...} gets evaluated before the param is passed to gsub,
All method parameters are evaluated before method invocation - this is
true for every method invocation in Ruby.
but the block is passed as code, so then it is evaluated after.
In the case of gsub the block is invoked once for each match.
Using the previous attempt, with a fresh irb session, I can see the
issue:
NoMethodError: private method `gsub' called for nil:NilClass
from
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/uri/common.rb:289:in
`escape'
from (irb):8
Note that my regexp has another weakness: the quote character not used
to quote the URI should be allowed as part of the URI. I did not want
to complicate things too much but if you want to deal with this the
regular expression must be made a bit more complex.
Wow, interesting. That would be incorrect HTML that the browser doesn't
deal with well, so I'll not worry about it for this case, but I would be
curious how it might be handled.
Basically you need an alternative and more capturing groups along the lines of
