What's purpose of function System`Private`LookupCodeByName and System`Private`LookupNameByCode

Question

These are useful function from their name.And they are kernel function since:

System`Private`HasAnyCodesQ /@ {System`Private`LookupCodeByName, 
  System`Private`LookupNameByCode}

{True, True}

But how to use them?

Are you really going to eventually ask about all the undocumented functions? — J. M.'s missing motivation, Jan 22 '17 at 16:53
But these turn out not be that interesting. One can do the same thing with top-level functions, pretty much as efficiently as needed. I think many of the internal functions are just auxiliary functions written for other higher-level functions. — Michael E2, Jan 22 '17 at 18:59

score 14 · Accepted Answer · edited May 17 '17 at 14:06

14

I tried random inputs until I got something to work. It looks like it has to do with character codes:

System`Private`LookupNameByCode[200]

"CapitalEGrave"

And then we can plug in the reverse:

System`Private`LookupCodeByName["CapitalEGrave"]

Edit by yode as J.M.'s comment

Grid[DeleteCases[{#, FromCharacterCode[#], 
     System`Private`LookupNameByCode[#]} & /@ 
   Range[100, 174], {_, _, $Failed}], Frame -> All]

edited May 17 '17 at 14:06

Alexey Popkov

answered Jan 22 '17 at 16:55

Greg Hurst

So, a bit like FromCharacterCode[] and ToCharacterCode[], but with the character names and not the characters themselves. – J. M.'s missing motivation Jan 22 '17 at 16:56
...and they (Lookup*) fail on ASCII characters. – Michael E2 Jan 22 '17 at 18:08
@MichaelE2 ... and also fail on such special characters as \! and \( etc.: System`Private`LookupNameByCode[ToCharacterCode["\!\(\)"]]. – Alexey Popkov May 17 '17 at 14:11

1 Answers1