[asdf-devel] source file encoding

[Pascal J. Bourguignon]

Faré <fahree at gmail.com> writes:

> On Fri, Apr 13, 2012 at 02:44, Douglas Crosher <dtc-asdf at scieneer.com> wrote:
>> The only practical solution seems to be to detect the encoding from the file.
>> I could write portable code for ASDF to read an ASCII header line
>> and look for encoding declarations, and handle a few common headers
>> (emacs has 'coding', LispWorks seems to use 'encoding' or 'external-format').
>> Auto-detection could handle some of the common codings,
>> but could be a big chunk of code.
>> The quicklisp project may be prepared to patch in headers
>> to system definition file using non-ASCII encodings,
>> and this could be largely automated.
>>
> Yes, this is a valid approach, though it is somewhat heavy in coding
> and will grow ASDF by a few hundred more lines of code.
> Don't forget to support the way Emacs detects encoding, etc.
> It is certainly more than I am willing to code,
> and making the semantics of loading more complex than I am comfortable with.
> Before you code it yourself,

There's no need to code it yourself, I've already done it:
https://gitorious.org/com-informatimago/com-informatimago/blobs/master/tools/make-depends.lisp#line316


> I'd like to hear about other users here what they think.
>
> An additional small thing I don't like about the approach is that
> you have to open a file twice, once to detect encoding,
> the other time to load or compile-file it, which is not atomic
> and can be slightly nasty (if e.g. the file is actually a URL or
> mounted on a weird filesystem or whatnot).
> But that's secondary.

You have to do what you have to do.  FILE-LENGTH has to read the whole
file to compute the number of characters in an UTF-8 file.


> Also, I'm not sure how big the market for such support is.
> There again, I'd like to hear from potential users.

Having written the above, I'd tend to be in favor of this approach.  On
the other hand, nowadays I put -*- coding:utf-8 -*- in all my files…


> PS: This long discussion on a relatively minor topic reminds me of
> Parkinson's Law of Triviality. What color should the bikeshed be painted?

It's not entirely trivial, you can spend quite some time on encoding
problems.


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/
A bad day in () is better than a good day in {}.