question of regexp select

[Tom Reilly]

Regexp error?
Page 538 Programming Ruby

m = /(.)(.)(\d+)(\d)/.select("TXH1138: The Movie")
p m.to_a


rb_tmp.rb:1: private method `select' called for /(.)(.)(\d+)(\d)/:Regexp
(NoMethodError)

Exit code: 1

Why should there be a NoMethodError for select?

Thanks
Tom Reilly

 

[daz]

Regexp error?
Page 538 Programming Ruby

m = /(.)(.)(\d+)(\d)/.select("TXH1138: The Movie")
p m.to_a


rb_tmp.rb:1: private method `select' called for /(.)(.)(\d+)(\d)/:Regexp
(NoMethodError)


Why should there be a NoMethodError for select?

There's no method Regexp#select, AFAIK.

PickAxe I shows:

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
p m.to_a #-> ["HX1138", "H", "X", "113", "8"]


Is that a second edition misprint?


daz

 

[Mark Hubbart]

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LgoKY2hlZXJzLApNYXJrCg==

 

[daz]

538 is the section on MatchData, which has a #select. Regexp has no
#select method.

So is the example the same as in the rdoc?:
http://www.ruby-doc.org/core/classes/MatchData.html#M000496

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
m.to_a #=> ["HX1138", "H", "X", "113", "8"]
m.select(0, 2, -2) #=> ["HX1138", "X", "113"]

i.e. it creates a MatchData object before calling select?

Therefore the confusion is due to a bug in MatchData#select -

:in `select': wrong number of arguments (3 for 0) (ArgumentError)

<re.c>

static VALUE
match_select(argc, argv, match)
int argc;
VALUE *argv;
VALUE match;
{
if (argc > 0) {
rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
}
else { [...]

rb_cMatch = rb_define_class("MatchData", rb_cObject);
[...]
rb_define_method(rb_cMatch, "select", match_select, -1);

</re.c>


daz

 

[ts]

d> m.select(0, 2, -2) #=> ["HX1138", "X", "113"]

sub(/select/, "values_at")


Guy Decoux

 

[daz]

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
m.to_a #=> ["HX1138", "H", "X", "113", "8"]
m.select(0, 2, -2) #=> ["HX1138", "X", "113"]

MatchData#select is deprecated (May 2003) - use #values_at:

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
p m.to_a #=> ["HX1138", "H", "X", "113", "8"]
p m.values_at(0, 2, -2) #=> ["HX1138", "X", "113"]


PickAxe bug.


(No need to post because Guy just answered

daz