# Unexpected error related to Unprotecting StringPartition

Posted 5 months ago
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 Unprotect@StringPartition StringPartition[n_Integer, d_Integer] := Function[str, StringPartition[str, n, d]] results in the following error on my machine: SetDelayed::write: Tag StringPartition in StringPartition[n_Integer,d_Integer] is Protected. I have added operator definitions to many other built-in functions using this methodology and StringPartition is the first one that gives me this error.Please let me know if I'm missing something here or if this error message is a bug?Thanks, Rian
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Posted 5 months ago
 I have a quite interesting observation of this function as well: In[1]:= Attributes[StringPartition] Out[1]= {Protected, ReadProtected} In[2]:= Unprotect@StringPartition Out[2]= {StringPartition} In[3]:= Attributes[StringPartition] Out[3]= {ReadProtected} In[4]:= StringPartition[n_Integer,d_Integer]:=Function[str,StringPartition[str,n,d]] During evaluation of In[4]:= SetDelayed::write: Tag StringPartition in StringPartition[n_Integer,d_Integer] is Protected. Out[4]= $Failed In[5]:= Attributes[StringPartition] Out[5]= {Protected,ReadProtected} Somehow the function is automatically protected again. It does not happen for Log in this online doc Answer Posted 5 months ago  From V11.3, I feel comfortable to deal with this type of operator definition with Curry In[3]:= op=Curry[StringPartition,{3,1,2}][1][2] Out[3]= Curry[StringPartition,{3,1,2}][1,2] In[4]:= op["abc"] Out[4]= {a,c} Answer  If you look at the definition of StringPartition, you'll see that it is just a stub loading a package, not a real function (in a fresh kernel, of course): ClearAttributes[StringPartition, {Protected, ReadProtected}] Definition@StringPartition StringPartition := SystemDumpAutoLoad[Hold[StringPartition], Hold[StringPart, StringPartition], "StringUtilities"] /; SystemDumpTestLoad The package redefines StringPartition and protects it again: StringPartition; ClearAttributes[StringPartition, {Protected, ReadProtected}] Definition@StringPartition StringPartition[StringUtilitiesDumpargs___]:=With[{StringUtilitiesDumpres=StringUtilitiesDumpoStringPartition[StringUtilitiesDumpargs]},StringUtilitiesDumpres/;StringUtilitiesDump`res=!=$Failed] This explains the behavior you observe. The workaround is to preload the package before making any new definitions as I made above. But remember that modifying built-in functions is dangerous and isn't recommened until you know exactly what you do...
Posted 5 months ago
 Hi Shenghui,Thank you for your response.I am familiar with Curry, however I would like to avoid defining a new symbol (op in your example) and instead would like to add an operator definition to the existing, built-in symbol StringPartition.Yes you are right, the unexpected behavior I was referring to in my question is exactly the fact that StringPartition for some reason automatically re-protects itself.Do you know why this is or how to go about fixing it?Thanks, Rian
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