On Tue, 25 Feb 2020 08:14:33 -0500, Tony Thigpen wrote:
>"regular expressions". What a misnamed item. It should be called "geek
>readable only expressions". :-)
>
The name is adopted from formal language theory, clearly a geeky field.
An alternative name is Chomsky type-3.
https://en.wikipedia.org/wiki/Chomsky_hierarchy#Type-3_grammars
It refers not to the template but to the target. I shudder to envision a
formal grammer for UNIX regexen.
On Tue, 25 Feb 2020 12:11:24 +0000, Seymour J Metz wrote:
>What is happening is that everything in the template before the string match
>'.'
>is a sub-pattern applied to the fragment to the left of the period. ...
>
Good description. Does IBM use the term "sub-pattern" anywhere in its
documentation?
On Tue, 25 Feb 2020 13:24:09 +0000, Seymour J Metz wrote:
>While the Eunix RE syntax is grotesque, the regexen are incredibly useful. I
>just wish that
>they had adopted the pattern syntax from SNOBOL or Wylbur.
>
There are two poles of UI design style:
o Ergonomic or keystroke economy. Frequently used
commands are single keystrokes with no lexical separator
between the command and its argument, as in the XEDIT
"/target" for a string search.
o Orderly command grammar.
I suspect that TSO begat CLIST and linemod EDIT, which begat
ISPF commands. Good in a script; terrible from the keyboard.
A very simple regex pattern, / ' " /, was formerly available in ISPF
EDIT only as F x'407d407f40'! Now that ISPF has regexen, it can
be the relatively transparent F R' ['] " '. But only the hex can be
used as a replacement.
-- gil
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