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digitalmars.D.bugs - [Issue 1630] New: Few suggestions for std.conv (D language 2.0)

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1630

           Summary: Few suggestions for std.conv (D language 2.0)
           Product: D
           Version: 2.006
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: aarti interia.pl


First of all I found new additions to Phobos really great! Thanks!

I would like to suggest here some extensions which could be useful:
1. parse() function does not allow to apply additional, user defined
transformations on consumed tokens. I mean for example additional checking for
matching parsed token to regular expression pattern. It would be probably
better to have just template function consume(T)() which returns consumed token
of specific type as string. Then it would be possible to convert consumed token
with to!(T) template. I see here 2 possibilities: replace parse with consume or
add additional template consume.

2. Conversion function template to!(T)() works great. It can even convert
arrays into string. Unfortunately the other way (converting from string into
array) is not possible, although I think it should. If it work properly it
would allow easy serialization of complex types. If request would be applied,
then probably it would be necessary to change representation of strings in
serialized form to use "" or ''. (See also next point.)

3. String parsing functions. It seems to be quite common task to parse
delimited with "" or '' strings from text. I think that in case of such
delimited strings there should be also escape characters supported, so e.g.
when in delimited string there is \" it should be properly interpreted as
character, not as delimiter. (BTW. Conversion to/from escape characters is also
quite common, so some functions in standard library would be great also.). I
think that quite a good solution would be to allow 3 forms for strings:
delimited with ", delimited with ' and without delimiters. In 3rd case there
should be no conversion for escape characters.

4. It should be possible to add custom parsers and converters. It will allow
full serialization solution on compile time.

In my library Doost/ProgramOptions I can not use much of new functionality
directly because of above problems.


--
Oct 31 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1630





------- Comment #1 from andrei metalanguage.com  2007-10-31 12:02 -------
1. parse() is meant to use known-in-advance data formats; a function closer to
what you mention is string.munch. An obvious addition will be to allow munch
with a regex, which is exactly what you mention.

2. to!(T) also has a more limited charter. Converting strings to arrays was not
considered appropriate for implementing at this level because there are so many
options (e.g., having the size prefix the string, various quoting mechanisms
etc.) that any particular design would have been too constraining. Some
higher-level, more abstract serialization ideas would be welcome. to!(T) does
not seem like the right level.

3. A Perl-like quotemeta function does indeed belong to the standard library
(probably in the string module though).

4. This is a bit vague. Adding a full-blown serialization solution is
worthwhile, but it will take some time. The to!(T) and parse!(T) families of
functions are only meant as backends for such a framework, not parts of its
architecture.


--
Oct 31 2007
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1630


Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei metalanguage.com
         AssignedTo|nobody puremagic.com        |andrei metalanguage.com


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