Re: Copy-on-write strings and mutation-sharing strings

[Marius Vollmer]

Kevin Ryde <address@hidden> writes:

> Marius Vollmer <address@hidden> writes:
>>
>> go crazy and try to break them!
>
> The build script (the scheme bit, not any C code) in the guile-gtk-1.2
> cvs exposes some breakage.  It bombs in a string-ref, looking like
> taking a substring has caused truncation of the originating string,
> maybe.

Now that is embarassing!  I got the substring operation totally wrong,
not taking into account that the substringed string might itself be a
substring.

I don't have time right now to fix it, but this is so embarrasing, I
must start blathering right away about how embarassing it is... should
be fixed today.

A simple test case is:

    guile> (substring (substring "0123456789" 3) 0 4)
    "0123"

The second substring gets a string with STRING_START != 0, which is
totally ignored.  Also mutation-sharing substrings would crash Guile,
as in:

    guile> (substring (substring/shared "0123456789" 3) 0 4)
    "'\x02
    \x00"

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