Re: valid values?
On Tue, 5 Mar 2019 at 01:23, Brad Gilbert wrote: > > Somewhere on the Internet I layed out the rules that I think that > should normally be followed, but I am not sure where. > Perhaps: https://stackoverflow.com/questions/54338491/string-matching-in-main-parameters -- Norman Gaywood, Computer Systems Officer School of Science and Technology University of New England Armidale NSW 2351, Australia ngayw...@une.edu.au http://turing.une.edu.au/~ngaywood Phone: +61 (0)2 6773 2412 Mobile: +61 (0)4 7862 0062 Please avoid sending me Word or Power Point attachments. See http://www.gnu.org/philosophy/no-word-attachments.html
Re: valid values?
On Mon, Mar 4, 2019 at 8:22 AM Brad Gilbert wrote: ... > Somewhere on the Internet I layed out the rules that I think that > should normally be followed, but I am not sure where. ... It would be nice to find it and add to the docs. -Tom
Re: valid values?
An Array isn't a type of Str. @ ~~ Str; # False Array ~~ Str; # False You can have an array that has a type constraint. (my Str @) ~~ Array[Str]; # True (my @ of Str) ~~ Array[Str]; # True Or you could check that all of the values of the Array are of some type. (my @ = ) ~~ *.all ~~ Str (my @ = ) ~~ (.all ~~ Str) This is one of the few times that it is acceptable to have a ~~ in a smart-match. sub test1(:@array? where .all ~~ Str) { say 'ok' } test1; # ok test1 array => ; # ok test1 array => (1,2,3); # Constraint type check failed in binding to parameter '@array'; … Somewhere on the Internet I layed out the rules that I think that should normally be followed, but I am not sure where. On Mon, Mar 4, 2019 at 5:32 AM Fernando Santagata wrote: > > Hi Brad, > > How far should I follow the rule that I should not use a smartmatch in a > where clause? > > I'm thinking of this: > > > sub test1(:@array? where Str) { say 'ok' } > &test1 > > test1() > Constraint type check failed in binding to parameter '@array'; expected > anonymous constraint to be met but got Array ($[]) > in sub test1 at line 1 > in block at line 1 > > > sub test2(:@array? where .all ~~ Str) { say 'ok' } > &test2 > > test2() > ok > > The where clause in test1() doesn't work, but is the clause in test2() > dangerous (action at a distance)? Should I rephrase it differently? > > On Mon, Mar 4, 2019 at 5:29 AM Brad Gilbert wrote: >> >> The `where` clause is already a smart-match, adding `~~` to it is not >> only redundant, it can cause confusing action at a distance. >> (By that I mean the right side of `where` is exactly the same as the >> right side of `~~`) >> >> You wouldn't write this: >> >> * ~~ (* ~~ 1|2|4|8|16) >> >> So don't write this either: >> >> … where * ~~ 1|2|4|8|16 >> >> --- >> >> It should be >> >> sub mysub(Int $value where 1|2|4|8|16) >>{ >> say "Got $value" >> } >> >> On Sun, Mar 3, 2019 at 4:16 AM Fernando Santagata >> wrote: >> > >> > Hi Todd, >> > is this what you're looking for? >> > >> > sub mysub(Int $value where * ~~ 1|2|4|8|16) >> > { >> > say "Got $value" >> > } >> > >> > mysub 2; # Got 2 >> > mysub 3; # Constraint type check failed in binding to parameter '$value'; >> > expected anonymous constraint to be met but got Int (3) >> > >> > On Sun, Mar 3, 2019 at 11:09 AM ToddAndMargo via perl6-users >> > wrote: >> >> >> >> Hi All, >> >> >> >> I want to pass an integer to a sub. The only >> >> valid values of the integer are 1, 2, 4, 8, and 16. >> >> >> >> Other than using "if" to test their values, is >> >> there a way to state that an integer can only >> >> have certain predefined values? >> >> >> >> Many thanks, >> >> -T >> >> >> >> -- >> >> ~~~ >> >> Having been erased, >> >> The document you're seeking >> >> Must now be retyped. >> >> ~~~ >> > >> > >> > >> > -- >> > Fernando Santagata > > > > -- > Fernando Santagata
Re: valid values?
Hi Brad, How far should I follow the rule that I should not use a smartmatch in a where clause? I'm thinking of this: > sub test1(:@array? where Str) { say 'ok' } &test1 > test1() Constraint type check failed in binding to parameter '@array'; expected anonymous constraint to be met but got Array ($[]) in sub test1 at line 1 in block at line 1 > sub test2(:@array? where .all ~~ Str) { say 'ok' } &test2 > test2() ok The where clause in test1() doesn't work, but is the clause in test2() dangerous (action at a distance)? Should I rephrase it differently? On Mon, Mar 4, 2019 at 5:29 AM Brad Gilbert wrote: > The `where` clause is already a smart-match, adding `~~` to it is not > only redundant, it can cause confusing action at a distance. > (By that I mean the right side of `where` is exactly the same as the > right side of `~~`) > > You wouldn't write this: > > * ~~ (* ~~ 1|2|4|8|16) > > So don't write this either: > > … where * ~~ 1|2|4|8|16 > > --- > > It should be > > sub mysub(Int $value where 1|2|4|8|16) >{ > say "Got $value" > } > > On Sun, Mar 3, 2019 at 4:16 AM Fernando Santagata > wrote: > > > > Hi Todd, > > is this what you're looking for? > > > > sub mysub(Int $value where * ~~ 1|2|4|8|16) > > { > > say "Got $value" > > } > > > > mysub 2; # Got 2 > > mysub 3; # Constraint type check failed in binding to parameter > '$value'; expected anonymous constraint to be met but got Int (3) > > > > On Sun, Mar 3, 2019 at 11:09 AM ToddAndMargo via perl6-users < > perl6-users@perl.org> wrote: > >> > >> Hi All, > >> > >> I want to pass an integer to a sub. The only > >> valid values of the integer are 1, 2, 4, 8, and 16. > >> > >> Other than using "if" to test their values, is > >> there a way to state that an integer can only > >> have certain predefined values? > >> > >> Many thanks, > >> -T > >> > >> -- > >> ~~~ > >> Having been erased, > >> The document you're seeking > >> Must now be retyped. > >> ~~~ > > > > > > > > -- > > Fernando Santagata > -- Fernando Santagata
Re: valid values?
On 3/3/19 8:29 PM, Brad Gilbert wrote: It should be sub mysub(Int $value where 1|2|4|8|16) { say "Got $value" } :-)