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Re: PATCH: provide %c and %u8c formatting in pickle printf()

From: Jose E. Marchesi
Subject: Re: PATCH: provide %c and %u8c formatting in pickle printf()
Date: Sat, 05 Oct 2019 12:37:28 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)

    >     But that seems a bit overkill?  An alternative, probably more natural,
    >     is to catch EOF around the loop, do the right thing, then re-raise:
    >     try
    >       THE_LOOP_INCLUDING_draw_ascii_line;
    >     catch if E_eof
    >     {
    >       draw_ascii_line;
    >       raise E_eof;
    >     }
    > Thinking about this... we have this in dump:
    >  try print_data :offset offset :top top :step 16#B;
    >  catch if E_eof { print "\n"; }
    > If we make `offset' and `top' globals in print_data (as opposed to
    > function arguments) then we could abstract the ascii printing into a
    > print_ascii_line function, and call it in that catch:
    >  try print_data :offset offset :top top :step 16#B;
    >  catch if E_eof { print_ascii_line; print "\n"; }
    Thinking a bit more about the problem, we can solve a lot of the
    issues by not goig through the loop twice, but only once: while going
    through the bytes, we print them out in hex but allso append the ASCII
    representation to a string, byte by byte. Once the end is reached, we
    just print the string with the collected ASCII representation. This
    solves several problems
       o it makes the code more compact and readable; just one loop and a
    final print
       o No complicated EOF catching per character, just at the very end,
    we print the half-collected line at the end (essentially your version
    above, but not a function call, but the collected ASCII)
       o it will probably also slightly easier to do the space-padding of
    lines in normal cases of running out of bytes (the other class of

Yes, that's a good idea.  It also avoids mapping each byte twice, which
is costly.
    Does pickle support appending characters to a string ? Or maybe
    address an character-array and set characters there.

Appending characters to a string:

 defvar bytes = "";
 bytes = bytes + 'x' as string;

Getting a character from a string:

 (poke) bytes[0]

Alternatively you can initialize an array of a constant number of
characters, and use it as a buffer.  The resulting code would be faster.

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