Re: gEDA-user: Unicode and Guile [was: couple of questions on attributes.]

[Peter Brett <peter@xxxxxxxxxxxxx>]

[ This is a really dull e-mail. You can probably safely skip it. ]

John Doty <jpd@xxxxxxxxx> writes:

> On Jun 28, 2011, at 4:17 AM, Peter Brett wrote:
>
>> 1) We need to support gnetlist backends when gEDA is compiled against
>>   Guile 1.8.x, which doesn't understand UTF-8. BTW, if you want to use
>>   non-ASCII characters in your attributes, I highly recommend to use
>>   Guile 2.x.
>
> Actually, UTF-8 attributes (names and values) work fine with Guile
> 1.8-based gEDA. The clever design of UTF-8 makes code intended for
> ASCII "just work" so long as it doesn't need to pick wide characters
> out of a string.

Let me spell it out:

Guile 1.8.x does not understand UTF-8, which means the vast majority of
standard Scheme string functions don't work according to the RnRS
specifications [1].

Guile 2.x does understand UTF-8, which means that all standard Scheme
string functions work according to the RnRS specifications.

If you are moderately careful, you can use Guile 1.8.x without running
into string encoding problems [2].  If you use Guile 2.x, you won't run
into string encoding problems.

Therefore, I *recommend* that if you wish to use non-ASCII Unicode in
your schematics or symbols, you should upgrade to using Guile 2.x.
Mainly because then things *will* actually "just work".

I hope that's clear enough for everybody.

                             Peter

[1] N.b. I do not necessarily mean that "they don't work".  I *do* mean
    that you can quite efficiently generate invalid UTF-8 that makes
    apps barf and people who triage bug reports cry.  Luckily, most
    gnetlist backends don't use anything other than string=?, format and
    string-append, which have no issues.

[2] Believe me, string encoding problems are incredibly tedious.

-- 
Peter Brett <peter@xxxxxxxxxxxxx>
Remote Sensing Research Group
Surrey Space Centre



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