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Re: original meaning of System` functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115377] Re: original meaning of System` functions
  • From: hemmecke <hemmecke at gmail.com>
  • Date: Sun, 9 Jan 2011 02:20:06 -0500 (EST)
  • References: <ig3pm2$jif$1@smc.vnet.net>

If it is impossible to access the original meaning of Mathematica
System` functions,
it is also impossible to truely protect implementation details of a
package.

Or is there a reliable way to hide the source code of a package?

Suppose someone has redefined

Unprotect[SetAttributes]; SetAttributes[_,_]:={}
Attributes[SetAttributes] = {Protected, Locked}

before loading the package code. The source code would be available
just by typing

??F

where F is an exported function of the package.

Ralf

On 01/06/2011 05:50 PM, Daniel Lichtblau wrote:
> Ralf Hemmecke wrote:
>> True, it looks impossible, but maybe there is still a way to get
>> System`ClearAll in its original Mathematica meaning. I simply want to
>> get access to the builtin behaviour of the "function". Possible or
>> impossible?
>>
>> Note, I am not asking for user-defined functions, but rather for
>> modified system-defined constructs. Deep inside the Mathematica
>> kernel, the original meaning must have been hardcoded. How to access
>> that?
>>
>> Ralf
>
> I may be misunderstanding the question, but I will mention that many of
> the System` function DownValues are implemented in C code. So you would
> not be able to access the actual definitions, if that is what you are
> seeking.
>
> If it is just that you want a way to "restore" those definitions for
> usage, that might be done within Block but not if you Lock/Protect the
> new definitions. Or at least not in a way I can see; this is a bit out
> of my usual area of coding.
>
> Daniel
>
>
>> On 01/05/2011 01:12 PM, Leonid Shifrin wrote:
>>> Hi,
>>>
>>> Since you both Protected and Locked these commands, it looks like you
>>> made all the steps to ensure that their definitions can not be altered
>>> in the same session, and thus their original definitions can not be
>>> inspected or used (at least AFAIK). Given the nature of these commands,
>>> I wonder whether this confirmation of impossibility to undo these
>>> changes was what you were actually after :)
>>>
>>> Regards,
>>> Leonid
>>>
>>>
>>> On Tue, Jan 4, 2011 at 3:51 PM, hemmecke <hemmecke at gmail.com
>>> <mailto:hemmecke at gmail.com>> wrote:
>>>
>>> Is there any way to call the original Mathematica behaviour of a
>>> function from the System context in case it has previously been
>>> unprotected and redefined?
>>>
>>> For example, how can I access the original meaning of ClearAll after
>>>
>>> Unprotect[ClearAll,Clear]; ClearAll[__]:=True;Clear[__]:=True;
>>>
>>> ?
>>>
>>> I just temporarily (i.e. in some safe environment) want to access the
>>> system defined meaning, but actually don't want to undo any modified
>>> behaviour.
>>>
>>> Ralf
>>>
>>> In[1]:= Unprotect[ClearAll,Clear]; ClearAll[__]:=True;Clear[__]:=True;
>>>
>>> In[2]:= SetAttributes[ClearAll,{Protected, Locked}]
>>>
>>> In[3]:= SetAttributes[Clear,{Protected, Locked}]
>>>
>>> In[4]:= a[x_]:=x^3
>>>
>>> In[5]:= ClearAll[a]
>>>
>>> Out[5]= True
>>>
>>> In[6]:= ClearAll[ClearAll]
>>>
>>> Out[6]= True
>>>
>>> In[7]:= System`ClearAll[a]
>>>
>>> Out[7]= True
>>>
>>> In[8]:= ??a
>>> Global`a
>>>
>>> a[x_] := x^3
>>>
>>>
>>
>


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