Ken Mankoff <mankoff@gmail.com> writes:

> On 2014-03-11 at 08:47, zwz wrote:
>> In my setup, there is 
>> (setq org-export-exclude-tags '("private" "exclude")
>>
>> and In my test.org:
>>
>> * test
>>
>> ** Not exported                :exclude:
>>    #+BEGIN_SRC ditaa :file test.png :cmdline -E
>>           +--------+---+---+---+---+---+---+---+  +---+---+---+---+---+---+---+---+
>>       x   | 0 cRED | 0 | 0 | 0 | 0 | 0 | 0 | 0 |  | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 |
>>           +--------+---+---+---+---+---+---+---+  +---+---+---+---+---+---+---+---+
>>    #+END_SRC
>>
>> ** blah blah
>>    blah blah blah
>>
>>
>> When I try to export it to pdf, the test.png is still generated,
>> although it is not used for the pdf at all.
>> So I think the export procedure may be optimized for more efficiency.
>
> No, because I often have code and sections I don't want exported, but
> I want their side-effects active. For example, code with sessions
> where part is not exported, but I need that code run so code
> elsewhere, using the same session, is able to run and be exported.

AFAIK, this depends if you use a session. When you are using a session,
*all* code blocks are evaluated, if you do not set the header argument
session, only the ones which are exported are evaluated - precisely the
reason you give.

Rainer

>
>   -k.
>
>

-- 
Rainer M. Krug

email: RMKrug<at>gmail<dot>com