use Perl

• Thanks (Score:2)

  by Juerd (1796)

  That's a very clear explanation of what I've thought for some time, but was unable to phrase.
  
  A quick way to upgrade yourself from level 2 to 3 is reading http://juerd.nl/site.plp/perluniadvice [juerd.nl] ;-).
  • Re:Thanks (Score:2)

    by miyagawa (1653) on 2008.02.20 17:50 (#61177) Homepage Journal

    Thank *you* for the good tutorial.
    
    So, I've been thinking there need to be some standards for CPAN modules to declare if it accept/return strings or bytes. (If they need to handle both)
    
    For instance, HTML::Parser has an instance method called utf8_mode [cpan.org].
    
    Another example (that triggered me to write this entry) is Catalyst's uri_for() method [cpan.org]. At some release the developers changed the implementation to accept only strings (UTF-8 flagged or not) in its %query_values hash.
    
    Based on the complaints and patches made by Japanese developers, they changed the code to accept both strings OR utf-8 bytes, by doing utf8::encode() if utf8::is_utf8(); Like said in the post, this might break latin-1 strings if it's not explicitly upgraded by users using utf8::upgrade() before passing it to the method.
    
    I was suggesting them to make another method, like uri_for_bytes, so as it won't do any utf8::encode() inside the module to treat everything as bytes. But another idea flashed me like "Hey, perl has a core pragma to say that".
    
    bytes.pm.
    
    Does this sound crazy if we change the behavior of these modules by looking at %^H hash values to see if bytes.pm is enabled? (Maybe we can wrap it like bytes::enabled). I know enabling bytes.pm affects functions like index(), substr() and length() globally, so this might not be what you want. They just might want to pass one argument as bytes, and let the other modules/behaviors still be in Unicode semantics. Maybe some packaged scope for bytes pragma?
    
    Hmm.

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    • Strings or bytes (Score:2)

      by Juerd (1796)

      Strings or bytes is not the right distinction, because both kinds are strings. I usually call them "text string" and "binary string", or "character string" and "byte string". Sometimes I call the former "Unicode string" to emphasize that all text strings are Unicode strings.
      
      A trap is the UTF-8 string, which is a byte string representing characters, and has "the flag" off (which to perluninewbies is confusing because this flag is called UTF8). Compare this with the result of pack "N*", LIST, which is a byte
      • Re: (Score:2)

        by miyagawa (1653)

        Hm, just to clarify, I prefer to use characters vs. bytes like you say. If I sometimes use "strings" somewhere, it's just a slip of keystrokes, or I meant Unicode strings instead.
        
        And also, I'm a bit afraid that you misunderstood what I meant with mention to bytes.pm. I didn't mean we should call "use bytes" in this situation to force string operations to be bytes-wise. Not at all.
        
        I meant declaring "use bytes" *might be* a good way for programmers to tell the module authors "Hey I want this module to do what
        • Re: (Score:2)

          by Juerd (1796)

          "use bytes;" is lexical: it cannot influence what a module does. I don't know who to thank for this, but I'm happy that at least my code won't be broken at a distance by the numerous uninformed and misinformed people who throw a "use bytes" at their code to replace one kind of (for them) vague behavior with another kind of vague behavior. :)
          
          Experience has show so far that the only workable way of supporting both byte strings and text strings in your function, is to provide two separate functions, or a mecha
          • Re: (Score:2)

            by miyagawa (1653)

            Agreed in both: we should use two different functions to accept characters or bytes, and also BLOB.pm would be useful to DWIM. :)