use-livecode Digest, Vol 222, Issue 8

[Mark Smith]

So, playing around a bit more I discovered “a.*” does not return words that “start with”, but rather words that “contain” the letter. So that explains “apple, banana”. What isn’t clear to me is I get the exact same result using “a.” with no asterisk, but if I search for “y.” it returns nothing rather than cherry. Consequentially I realize my confusion is due to a limitation of what these characters mean to regex. Can anyone clarify for me what the “.” and “*” are doing to change the filter? 

Thanks

> On Mar 7, 2022, at 11:05 AM, Mark Smith <marksmithhfx at gmail.com> wrote:
> 
> I am not an expert in regex or filtering by any means so Quentin’s message prompted me to take a closer look. I started with the dictionary entry for filter and I found this simple example:
> filter items of "apple,banana,cherry" with regex pattern "b.*"
> 
> Since we are not specifying a destination, the result is going into the “it" variable. I tried that and got the expected result “banana”. Next I tried “c.*” and got cherry and “d.*’ and got nothing. All good. Finally I tried “a.*” and got “apple, banana”. I was a bit surprised by that. Does anyone know why “a.*” breaks the pattern of returning a single item? Does it have something to do with the item being in the first position in the string? 
> 
> BTW, I did try putting the result into a variable and displaying that (… into temp; put temp) and got the same result. 
> 
> Also, I thought I might try a few experiments using “without regex pattern” and using “a.*” as the argument returned “cherry” so at least whatever it is doing it is consistent.
> 
> Mark
> 
> 
>> On Mar 7, 2022, at 8:58 AM, Quentin Long via use-livecode <use-livecode at lists.runrev.com <mailto:use-livecode at lists.runrev.com>> wrote:
>> 
>> sez j. landman gay:
>>> Interesting idea. There are 25 letters on each board, some are always repeats. I think I'd need 
>>> a good regex so I wouldn't have to run the filter command multiple times. How's your regex?
>> 
>> I see you've already implemented something, but just for grins, here's my thought re: the One True Regex for this situation:
>> AbsentChars is the name of a variable which contains all the letters that *aren't* on the board. My first attempt at the regex is…
>> filter lines of WordList without "*[AbsentChars]*"
>> However, that will remove all words that contain at least one letter in the specific character string "absentchars", which is not what I want. So, bring out the "do" keyword…
>> do ("filter lines of WordList without" && quote & "*" & AbsentChars & "*" & quote)
>> 
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