Re: Babel, Python and UTF-8

From: Dan Davison <dandavison7@gmail.com>
To: "Thomas S. Dye" <tsd@tsdye.com>
Cc: Vincent Beffara <vbeffara@ens-lyon.fr>, emacs-orgmode@gnu.org
Subject: Re: Babel, Python and UTF-8
Date: Mon, 06 Dec 2010 18:23:59 +0000	[thread overview]
Message-ID: <87sjyaep4w.fsf@gmail.com> (raw)
In-Reply-To: <9CDC3D4C-6C60-49C7-B7AB-205511BFC8C1@tsdye.com> (Thomas S. Dye's message of "Mon, 6 Dec 2010 06:42:55 -1000")

"Thomas S. Dye" <tsd@tsdye.com> writes:

> Hi Dan,
>
> Emacs configuration is one of the highest barriers to entry for
> potential adopters of Org-mode, IMO.  The idea of context-sensitive
> configuration is potentially terrific.  It gets the user to work more
> quickly than would otherwise be the case.  The problem I've run into
> is that exiting a buffer doesn't change the configuration back to some
> initial, or base, state.  I'm on to the next task but still configured
> to do the last thing.

Hi Tom,

I think someone else suggested using buffer-local variables to address
this problem, and I think that's the correct suggestion. One of the
examples below shows how to set a buffer-local value:

[...]

> #+source: document-config
>> #+begin_src emacs-lisp
>> (set (make-local-variable 'org-edit-src-content-indentation) 0)
>> #+end_src

As it happens, for that particular setting to be useful requires a patch
that is pending review, but, in general, I think this is the way to do
what you're describing.

Dan

>>
>> #+source: start-ess
>> #+begin_src R :session *R session*
>>  a <- 1
>> #+end_src
>>
>> # Local variables:
>> # eval:(sbe "document-config")
>> # eval:(sbe "start-ess")
>> # End:
>>
>>
>> Dan
>>
>>>>
>>>> Very cool ! That does all I want, thanks for the info. For multi-
>>>> line it
>>>> is a bit heavy to write, with lots of \n and preamble .= "lskjd",
>>>> but I
>>>> can live with that. Unless there is a way already to write something
>>>> like this ?
>>>>
>>>> #+source: my-preamble
>>>> #+begin_src python :return preamble
>>>>  # -*- coding: utf-8 -*-"
>>>>  import os,sys,whatever
>>>> #+end_src
>>>>
>>>> #+begin_src python :preamble
>>>> (org-babel-get-and-expand-source-code-
>>>> body my-preamble) :return s
>>>>  s = "é"
>>>> #+end_src
>>>>
>>>> There is org-babel-get-src-block-info but it looks at the block
>>>> around
>>>> (point), not by name ... so I guess it would not be too hard to
>>>> write
>>>> the extraction method, but it might be somewhere in the code
>>>> already.
>>>>
>>>
>>> Yes, the following uses an internal Babel function, but is probably
>>> much
>>> simpler
>>>
>>> #+results: my-preamble
>>> : # -*- coding: utf-8 -*-
>>> : import os,sys,whatever
>>>
>>> #+begin_src python :preamble (org-babel-ref-resolve "my-
>>> preamble") :return s
>>> s = ""
>>> #+end_src
>>>
>>> Note that as written this will return the following python error
>>>
>>> Traceback (most recent call last):
>>>  File "<stdin>", line 2, in <module>
>>> ImportError: No module named whatever
>>>
>>>>
>>>>>> One naive question : why is the code path different for tangling
>>>>>> and
>>>>>> evaluation ? One would think that a natural way for evaluation
>>>>>> would be
>>>>>> to tangle the current block (plus included noweb stuff etc) into a
>>>>>> temporary file and eval that file ... and that would enable
>>>>>> shebang for
>>>>>> evaluation as well. There must be something I am missing here.
>>>>>
>>>>> Tangling works for *any* programming language, even those which
>>>>> have yet
>>>>> to be created and have no explicit Emacs or Org-mode support,
>>>>> this is
>>>>> because on tangling the code block is simply treated as text.
>>>>
>>>> As far as I understood from testing, tangling does adapt to the
>>>> language
>>>> (at least to implement :var in a suitable way), so I was under the
>>>> impression that evaluating could be implemented as some kind of
>>>> wrapping
>>>> around the tangled output - and obviously the wrapping would have
>>>> to be
>>>> language-specific even if for the most part the tanglong is not.
>>>>
>>>
>>> Yes, some language specific features (e.g. variable expansion) can be
>>> used by the tangling mechanisms if such features are defined for the
>>> language in question, however tangling can be done in the absence
>>> of any
>>> language specific features and thus works for any arbitrary language.
>>>
>>> That shebang and preamble should remain separate for the other
>>> reasons
>>> mentioned in my previous email.
>>>
>>>>
>>>> I am just discovering all of this, sorry if I have horrible
>>>> misconceptions about the thing ...
>>>>
>>>
>>> No problem, it is a fairly (but I don't think overly) complex system.
>>>
>>>>
>>>> Regards,
>>>>
>>>>        /v
>>>>
>>>>
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