Re: [Pharo-users] Testing a Unicode Character's Category

[Prof. Andrew P. Black]

Hi Richard,

Normally I agree with you, and prefer boolean methods 

        inCatagoryCc: aChar
        isCategorySm: aChar
to 
        categoryOf: aChar == #Cc
        categoryOf: aChar == #Sm

In this particular case, though, the category codes are part of the Unicode 
Standard, so perhaps exposing them isn’t so bad.  Moreover, there is meaning 
encoded into the symbols — for example, all the letter categories start with L. 
 So one could write an isLetter test like this

Character >> isLetter
        ^ (Unicode categoryOf: self) first == $L

rather than 

Character >> isLetter
        Unicode inCategoryLl ifTrue: [ ^ true ].
        Unicode inCategoryLm ifTrue: [ ^ true ].
        Unicode inCategoryLo ifTrue: [ ^ true ].
        Unicode inCategoryLt ifTrue: [ ^ true ].
        Unicode inCategoryLu ifTrue: [ ^ true ].
        ^ false

There is still the disadvantage that a typo in the Category name (typing #L1, 
for example, when one means #Ll) is likely to go undetected.

        Andrew