隨筆 groovy閉包

|||

class

enclosing
assert
whatisthisobject()
==this                   
def whatisthis =
assert
whatisthis()
==this}}
class
enclosedininnerclass
}void
run()}
class
nestedclosurescl(
)}assert
nestedclosures()
==this
}}

class

enclosing
assert
whatisownermethod()
==this                   
def whatisowner =
assert
whatisowner()
==this}}
class
enclosedininnerclass
}void
run()}
class
nestedclosurescl(
)}assert
nestedclosures()
== nestedclosures            
}}

class

enclosing
def cl2 =
assertcl(
)==cl2(
)assertcl(
)==this                                 
def enclosed =
.call()
}assert
enclosed()
== enclosed                       
}}

class

person
def p =
newperson
(name:
'igor'
)def cl =
cl.delegate = p                                 
assertcl(
)=='igor'

def x =

1def gs =
"x = $"
assert gs ==
'x = 1'
//true
x =2
assert gs ==
'x = 2'
//false

解決方法：

def x =

1def gs =
"x = $"
assert gs ==
'x = 1'
x =2
assert gs ==
'x = 2'

def ncopies =

def twice = ncopies.
curry(2
)assert
twice
('bla')==
'blabla'
assert
twice
('bla')==
ncopies(2
,'bla'
)

def ncopies =

def blah = ncopies.
rcurry
('bla'
)assert
blah(2
)=='blabla'
assert
blah(2
)==ncopies(2
,'bla'
)

def fib

fib =
assert
fib(15)
==610
// slow!

fib =

.memoize()
assert
fib(25)
==75025
// fast!

def plus2  =

def times3 =
def times3plus2 = plus2 << times3
assert
times3plus2(3
)==11assert
times3plus2(4
)==plus2
(times3(4
))def plus2times3 = times3 << plus2
assert
plus2times3(3
)==15assert
plus2times3(5
)==times3
(plus2(5
))// reverse composition
assert
times3plus2(3
)==(times3 >> plus2)(3
)

def factorial

factorial =
factorial = factorial.
trampoline()
assert
factorial(1
)==1assert
factorial(3
)==1*
2*3assert
factorial
(1000
)// == 402387260.. plus another 2560 digits

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