Python -Vs- Ruby: A regexp match to the death!
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From: MRAB on 8 Aug 2010 21:14 rantingrick wrote: > Hello folks, > [snip] > --------------------- > Strings > --------------------- > Single line strings are exactly the same in both languages except in > Ruby double quoted strings are backslash interpreted and single quote > strings are basically raw. Except Ruby introduces more cruft (as > usual) in the form of what i call "lazy man" stings.... > >>>> a = %w{ one two three} > ["one", "two", "three"] >>>> s = %{one two three} > one two three >>>> repat = %r{one two three} > /one two three/ > > ... only good for hand coding! > From Perl. > ---------------------- > Multi Line Strings > ---------------------- > Ha. Ruby does not really have multi line strings. Ruby has what they > call a "Here Doc". Besides picking the most boneheaded name for such > an object they also introduced and even more boneheaded syntax. To > define a "Here Doc" (god i hate that name!) you start with double > greater than ">>" and immediately follow with an identifier token of > you choice (it can be anything your dirty little mind can come up > with. > >>> HEREDOC > this is the body > of a > here doc. Why the > hell did they not just > use triple quotes like Python did. > Now i will need to remember some token to know where' > i stopped > HEREDOC > > As you can see it is another example of tacked on functionality that > was not carefully considered before hand. Anyway here are the > regexp's... > > Python: r'""".*?"""' > Python: r"'''.*?'''" > Ruby: r'<<(\w+).*?(\1)' > Also from Perl. I don't know what the point of your post was. We already know that we prefer Python; that's why we're here! :-) And anyway, being nasty about other languages feels unPythonic to me...
From: Steven D'Aprano on 8 Aug 2010 21:15 On Sun, 08 Aug 2010 17:43:03 -0700, rantingrick wrote: > Ha. Ruby does not really have multi line strings. Except, of course, it does, as you go on to show. > Ruby has what they > call a "Here Doc". Besides picking the most boneheaded name for such an > object It's standard terminology that has been around for a long time in many different languages. http://en.wikipedia.org/wiki/Here_document > they also introduced and even more boneheaded syntax. To define a > "Here Doc" (god i hate that name!) you start with double greater than > ">>" and immediately follow with an identifier token of you choice (it > can be anything your dirty little mind can come up with. > >>>HEREDOC > this is the body > of a > here doc. Why the > hell did they not just > use triple quotes like Python did. > Now i will need to remember some token to know where' i stopped > HEREDOC Incorrect. [steve(a)sylar ~]$ irb irb(main):001:0> s = >>END SyntaxError: compile error (irb):1: syntax error s = >>END ^ from (irb):1 irb(main):002:0> s = <<-END irb(main):003:0" Multi-line text irb(main):004:0" goes here irb(main):005:0" END => "Multi-line text\ngoes here\n" irb(main):006:0> puts s Multi-line text goes here => nil irb(main):007:0> > As you can see it is another example of tacked on functionality that was > not carefully considered before hand. I disagree. It's an old and venerable technique, and very useful on the rare occasion that you have lots of quotation marks in a string. Whether those rare occasions are common enough to require specialist syntax is another question. In Python, the idea is that two heredocs (''' and """) is enough for anybody. That makes it difficult to write a string literal like, e.g.: Python strings have four delimiters: (1) single quote ' (2) double quote " (3) single-quote here-doc ''' (4) double-quote here-doc """ plus equivalent raw-strings of each kind. Trying writing that as a single literal in Python without escapes. There are work-arounds, of course, like using implicit concatenation, but they're ugly. In Ruby they decided to be more general, so you can define whatever heredoc you need to quote whatever literal string you need. That's not bone-headed. -- Steven
From: rantingrick on 9 Aug 2010 03:29 On Aug 8, 8:15 pm, Steven D'Aprano <st...(a)REMOVE-THIS- cybersource.com.au> wrote: > In Ruby they decided to be more general, so you can define whatever > heredoc you need to quote whatever literal string you need. That's not > bone-headed. Devils Advocate! PS: Man you're irb main was so full of cobweb i could barley see the code... haa... haaaa... hachew!. ;-)
From: Steven D'Aprano on 9 Aug 2010 04:21 On Mon, 09 Aug 2010 00:29:19 -0700, rantingrick wrote: > On Aug 8, 8:15 pm, Steven D'Aprano <st...(a)REMOVE-THIS- > cybersource.com.au> wrote: > >> In Ruby they decided to be more general, so you can define whatever >> heredoc you need to quote whatever literal string you need. That's not >> bone-headed. > > Devils Advocate! > > PS: Man you're irb main was so full of cobweb i could barley see the > code... haa... haaaa... hachew!. ;-) irb's default prompt is a bit too verbose for my tastes, but Python allows you to customise its prompt too. You'll often see people here posting copy/pastes with a customised prompt, so obviously some people like that sort of thing. Me, my biggest gripe with the interactive interpreter is that using >>> as a prompt clashes with > as the standard quoting character in email and news, but Guido has refused to even consider changing it. And that it's quite finicky about blank lines between methods and inside functions. Makes it hard to paste code directly into the interpreter. And that pasting doesn't strip out any leading prompts. It needs a good doctest mode. -- Steven
From: Stefan Schwarzer on 9 Aug 2010 07:42
Hi Steven, On 2010-08-09 10:21, Steven D'Aprano wrote: > And that it's quite finicky about blank lines between methods and inside > functions. Makes it hard to paste code directly into the interpreter. > > And that pasting doesn't strip out any leading prompts. It needs a good > doctest mode. ipython [1] should help here: IPython 0.10 -- An enhanced Interactive Python. ? -> Introduction and overview of IPython's features. %quickref -> Quick reference. help -> Python's own help system. object? -> Details about 'object'. ?object also works, ?? prints more. In [1]: %paste? Type: Magic function Base Class: <type 'instancemethod'> String Form: <bound method InteractiveShell.magic_paste of <IPython.iplib.InteractiveShell object at 0xb740096c>> Namespace: IPython internal File: /usr/lib/pymodules/python2.6/IPython/Magic.py Definition: %paste(self, parameter_s='') Docstring: Allows you to paste & execute a pre-formatted code block from clipboard. The text is pulled directly from the clipboard without user intervention. The block is dedented prior to execution to enable execution of method definitions. '>' and '+' characters at the beginning of a line are ignored, to allow pasting directly from e-mails, diff files and doctests (the '...' continuation prompt is also stripped). The executed block is also assigned to variable named 'pasted_block' for later editing with '%edit pasted_block'. You can also pass a variable name as an argument, e.g. '%paste foo'. This assigns the pasted block to variable 'foo' as string, without dedenting or executing it (preceding >>> and + is still stripped) '%paste -r' re-executes the block previously entered by cpaste. IPython statements (magics, shell escapes) are not supported (yet). See also -------- cpaste: manually paste code into terminal until you mark its end. Unfortunatey, when I enter In [2]: %paste at the prompt it gives me (before I pasted anything) In [2]: %paste ------------------------------------------------------------ File "<string>", line 1 http://pypi.python.org/pypi/ipython/0.10 ^ SyntaxError: invalid syntax So far, I couldn't find anything on the net on this. [1] http://pypi.python.org/pypi/ipython Stefan |