Inner classes: Difference between revisions

=={{header|J}}==

J allows inner classes, but because such classes are always public,

there is little or no utility to be had nesting classes in J.

Class definition for task:

<syntaxhighlight lang=J>coclass 'baggagecheck'

create=: {{

data=: keys=: i.0

mysn=: '' conew 'serialnumber'

}}

create_serialnumber_=: {{number=: 0}}

destroy_serialnunber_=: codestroy

get_serialnumber_=: {{number=: 1+number}}

destroy=: {{

destroy__mysn ''

codestroy ''

}}

checkin=: {{

sn=.get__mysn''

data=: data,<y

keys=: keys,sn

sn

}}

checkout=: {{

r=.>(keys i. y){data

b=. keys~:y

data=: b#data

keys=: b#keys

r

}}</syntaxhighlight>

Example use:

<syntaxhighlight lang=J> checker=: '' conew 'baggagecheck'

checkin__checker 'suitcase'

1

checkin__checker 'box'

2

checkin__checker 'bicycle'

3

checkout__checker 2

box

</syntaxhighlight>