Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Preserve notebook's $ContextPath between sessions /

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104998] Re: [mg104967] Preserve notebook's $ContextPath between sessions /
  • From: Leo Alekseyev <dnquark at gmail.com>
  • Date: Tue, 17 Nov 2009 05:14:39 -0500 (EST)
  • References: <4e3ad400911161117o4867d19bi39f5a63a09ad3f4c@mail.gmail.com>

> Using the "Other..." context mechanism precisely solves the problem you a sked
> about in your original email (i.e., close a notebook, re-open it...presum ably in
> the same session...and get $ContextPath preserved).  Your response adds several

Ah, I didn't test this in the same session; you are right.  But this
is not what I was looking for.  If I already have a session running,
chances are I can just copy/paste the relevant cells from some
notebook that's already open.


> other requests which, if implemented, would leave the system considerably more
> customizable, but considerably less general and easy to use.  It would also tie
> our hands in certain ways.

Well, that's not necessarily true -- the current behavior is probably
optimal for the average user and I don't advocate changing the
defaults, just providing an option for customizing them.

> I'm not sure why you couldn't just solve your problems by adding the explicit
> code you want in initialization cells.  They'll evaluate first every single time
> you open (or close, then re-open) the notebook, and it allows you total
> flexibility in configuring things however you want to configure them.

That is one solution, and I am already using it in places.  That still
requires me to copy/paste the initialization cells when I create a new
notebook.

You are right in that everything I want to do can be done one way or
another; I was just hoping to be able to wrap it in a concise utility
function (but it doesn't seem possible for reasons described in
previous messages).

--Leo

> On Mon, 16 Nov 2009 14:17:46 -0500, Leo Alekseyev wrote:
>> John, thanks for your response.
>>
>> Since there can be many session-dependent volatile contexts, it
>> probably wouldn't be a good idea to save them all by default -- which
>> is probably why that feature isn't there.  On the other hand, it would
>> be nice to offer the user a greater control over this: for instance, I
>> am simply trying to avoid doing
>>
>> SetOptions[EvaluationNotebook[],CellContext->Notebook];
>> Needs/@{"foo`","bar`"} (* which have already been autoloaded by
>> init.m, but are now hidden *)
>> AppendTo[$ContexPath,"Global`"]; (* in some sessions it's good to have
>> a "read-only" access to global context *)
>>
>> at the start of every notebook that I want to set up like that.
>> Specifying a "Other..." context as you suggested doesn't solve this
>> problem because the packages and loaded contexts are still hidden.
>>
>> I am just surprised there isn't an easy mechanism to save/retrieve the
>> context info.
>>
>> By poking around I noticed there's a variable
>> Global`Private`SavedContextInfo["$ContextPath"].
>> However, it looks like the SavedContextInfo variables cannot be made
>> persistent -- correct me if I am wrong.
>>
>> I tried writing the following wrapper function:
>>
>> test2[] := (SetOptions[EvaluationNotebook[],
>> CellContext -> Notebook]; (AppendTo[$ContextPath, #1] &) /@
>> Global`Private`SavedContextInfo["$ContextPath"]; $ContextPath =
>> DeleteDuplicates[$ContextPath])
>>
>> However, it appears that only the SetOptions[EvaluationNotebook[],
>> CellContext -> Notebook] command takes effect when written like this
>> *unless invoked twice in two separate cells with a fully-qualified
>> symbol name.  This seems kind of inelegant (and trying to do this
>> voodoo programmatically by manipulating notebooks with kernel
>> functions is ugly and doesn't work well).  I am still curious if there
>> is a good way around this.
>>
>> --Leo
>>
>>
>> On Mon, Nov 16, 2009 at 10:44 AM, John Fultz <jfultz at wolfram.com> wrote:
>>> Yes, that's right.  Mathematica is not just changing the context, but
>>> trying to
>>> sandbox a number of evaluation side effects from notebooks which are
>>> operating
>>> in another context, including...
>>>
>>> * $Context (of course)
>>> * $ContextPath
>>> * The state of In[]/Out[] numbering
>>> * The Out[] history
>>>
>>> In a notebook set with a unique notebook-level context, no attempt is
>>> made to
>>> recover the same context when you close and open the notebook again,
>>> and the
>>> context you used isn't stored anywhere in the file.  I don't think th=
at
>>> occurred
>>> to anyone here when designing the feature, and I'm not entirely certain
>>> whether
>>> it would be generally desirable to do so.
>>>
>>> But, what you want to do is easy enough.  Instead of specifying a
>>> notebook-unique context, specify a named context of your choice (i.e.,
>>> the
>>> "Other..." option).  Everything will be remembered as long as it's
>>> using the
>>> same context name, and by hard-coding the name, you can guarantee that.
>>>  Down
>>> side...you'll have to make sure you pick a unique name.  But that's
>>> probably not
>>> so difficult...you could choose a name based upon the file name, for
>>> example.
>>> You could write a button which does this, too.  I'll leave that as an
>>> exercise
>>> for the reader.
>>>
>>> Sincerely,
>>>
>>> John Fultz
>>> jfultz at wolfram.com
>>> User Interface Group
>>> Wolfram Research, Inc.
>>>
>>>
>>> On Sun, 15 Nov 2009 05:56:32 -0500 (EST), dnquark wrote:
>>>> I have fallen into the habit of making the default context of the
>>>> notebooks private by issuing the command
>>>> SetOptions[EvaluationNotebook[], CellContext->Notebook]
>>>> at the start of every notebook session.  However, I typically add
>>>> several other contexts to $ContextPath; I even wrote a utility
>>>> function to easily do all this automatically.
>>>>
>>>> It turns out, though, that upon closing and reopening the notebook
>>>> Mathematica puts only "Notebook$$xx`" and "System`" contexts in
>>>> $ContextPath.  My question is -- is there a way to make _my custom_
>>>> $ContextPath persistent between sessions in the same way as
>>>> {"Notebook$
>>>> $xx`", "System`"} context list is persistent?..  Or at least, can I
>>>> store custom metadata with the notebook -- i can always write a
>>>> wrapper function to retrieve it.
>>>>
>>>> Thanks,
>>>> --Leo
>
>
>
>


  • Prev by Date: Re: Re: Re: Wrong limit?
  • Next by Date: Re: Undo in Mathematica
  • Previous by thread: Re: shadow warning with function parameters and local module variables
  • Next by thread: Define a function as a graphics directive?