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Re: original meaning of System` functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115290] Re: original meaning of System` functions
  • From: Ralf Hemmecke <hemmecke at gmail.com>
  • Date: Thu, 6 Jan 2011 02:07:05 -0500 (EST)

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

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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