Thx for those reviews.
And interesting paper.
Phil
On Sat, Dec 15, 2018, 04:20 Richard O'Keefe <rao...@gmail.com wrote:
> Starting from the top:\
> (0) It's not *wrong* to start a selector with a capital letter, but
> it is certainly unusual.
> (1) Intention-revealing names are good. That's why this name is bad.
> It does not *delete* anything.
> (2) The comment again says "delete" but nothing is deleted. Comments
> that mislead are worse than no comments.
> (3) An issue I have seen over and over in student code (in other
> programming languages) is writing regular expressions as string
> literals where they are used, so that every time you try a match
> the regular expression gets recompiled, over and over again.
> You're not exactly doing that, but you *are* rebuilding patterns
> over and over again. It would make more sense to hold a
> forbiddenPatterns collection.
> (4) You are saying "(coll reject: [..test..]) notEmpty", building an
> entire collection just to ask whether it has any members. What
> you want to know is "are there any elements of coll that do not
> satisfy the test", which can be expressed as
> (coll allSatisfy: [..test..]) not. (Sadly there is no
> #notAllSatisfy:, although #notAnySatisfy: *does* exist under the
> name #noneSatisfy:.
> (5) #match: is a highly risky way to look for a substring. What if
> you want to look for a literal # or * ? What if you need to
> look for 'Boring' but not 'boring'? ("Boring" is a perfectly
> good surname.)
> (6) You really don't need the "result" variable.
>
> allowedWords
> "Answer those words which do not contain any forbiddenWord
> as a substring."
> ^words select: [:each |
> forbiddenWords noneSatisfy: [:forbidden |
> <<each includes forbidden as a substring>>]]
>
> (7) You can find out how to do the <<part>> by looking at the methods
> for String. You will find several candidate methods.
> (8) Of course, if there are W words and F forbidden words, in the
> worst case you'll do W*F substring inclusion tests. This is not
> good. "Multiple pattern matching" is a much-studied problem,
> see for example Wu and Manber's paper
>
> http://web.archive.org/web/20130203031412/http://www.inf.fu-berlin.de/inst/ag-bio-expired/FILES/ROOT/Teaching/Lectures/WS0506/WeiterfThemenBioinf/papers/FastAlgorithmMultiPatternSearching-WuManbers-TR94.pdf
> There is more recent work also.
>
> Does anyone know whether there's a multiple pattern algorithm for
> Pharo? One could always fall back on ternary search trees...
>
>
>
> On Fri, 14 Dec 2018 at 05:13, Roelof Wobben <r.wob...@home.nl> wrote:
>
>> Hello,
>>
>> I have this code :
>>
>> FindAndDeleteWordsWithForbiddenParts
>> "deletes all the words that contain forbidden parts"
>>
>> | result |
>> result := words
>> select: [ :word |
>> [ (forbiddenWords reject: [ :forbidden | '*' , forbidden , '*'
>> match: word ]) isNotEmpty ]
>> on: NotFound
>> do: [ false ] ].
>> ^ result
>>
>>
>> but I see warnings that I have to use a stream instead of string
>> concentation.
>>
>> Anyone hints how to do so ?
>>
>> Roelof
>>
>>
>>
