Re: Cell["\<\ ... \>", ... ; TextData[...]

*To*: mathgroup at smc.vnet.net*Subject*: [mg114775] Re: Cell["\<\ ... \>", ... ; TextData[...]*From*: John Fultz <jfultz at wolfram.com>*Date*: Thu, 16 Dec 2010 05:51:39 -0500 (EST)

Cell[_String] is equivalent to Cell[TextData[{_String}]] as far as the front end is concerned. The former is just an abbreviation of the latter syntax, which is necessarily used when the contents are more complex (e.g., contain styles or buttons). The \<\> business dates back to a hoarier day (in my opinion) in the design of strings in Mathematica. Once upon a time, Mathematica had an odd interpretation of newlines which I probably made more sense in the days of 80 character terminal usage. You'll have to forgive me...my memory is fuzzy here, and I don't have an old Mathematica text to double-check this from my current location...but I believe the issue was something like this... "abc\ d" ...with the newlines and spaces as shown, being equivalent to "abc d" (with just the single space). The \<\> business forced everything inside the string to really be interpreted literally, with backslash at the end of a line meaning to simply escape the newline, and do nothing special to leading spaces. Since the Mathematica notebook format generally wraps at about 70 characters, the non-literal interpretation would have made the representation of more than 70 consecutive spaces difficult. The modern Mathematica notebook format (introduced in 1996) was always made to be interpreted properly as a Mathematica expression should you call Get[] on it from the kernel. So this syntax was standardized, and is still used today. Now, the kernel simply ignores the \<\> delimiters as you can see below: In[1]:== StringLength["\<x\>"] Out[1]== 1 Sincerely, John Fultz jfultz at wolfram.com User Interface Group Wolfram Research, Inc. On Wed, 15 Dec 2010 07:51:11 -0500 (EST), kj wrote: > > > When I examine the source code of Mathematica notebooks, I often > see Cell objects whose first argument is preceded by > > "\<\ > > and followed by > > \ > \>" > > E.g. > > Cell["\<\ > Yet another undocumented item.\ > \>", "Text"... > > What do these delimiters mean? And how do they differ from the > TextData symbol? (The latter is also undocumented, but at least > I've seen "cameo appearances" of it in the documentation.) > > TIA! > > ~kj