In javascript I can do following:
var some = 100;
var param1 = 1;
func1(param1, function(res1) {
var param2 = res1 + some;
func2(param2, function(res2) {
// ...
});
});
In php same:
$some = 100;
$param1 = 1;
func1($param1, function($res1) use ($some) {
$param2 = $res1 + $some;
func2($param2, function($res2) {
// ...
});
});
How can I do same thing in python?
................................................
Pass functions as arguments.
some = 100
def callback1(res1):
param2 = res1 + some
func2(param2, callback2)
def callback2(res2):
...
param1 = 1
func1(param1, callback1)
I see that you tagged asynchronous as well. Python is NOT asynchronous. But python functions are also first class objects just like javascript and php. So, you can do the same thing in python as well.
def func1(data, nextFunction = None):
print data
if nextFunction:
nextFunction()
def func(data, nextFunction = None):
print data
nextFunction(data * 10)
func(1, func1)
Output
1
10
Inline function definitions are restricted in python but it is still possible with lambda functions. For example,
data = ["abcd", "abc", "ab", "a"]
print sorted(data, key = lambda x: len(x)) # Succinctly written as key = len
Output
['a', 'ab', 'abc', 'abcd']
Functions are first class objects in Python, and you can nest them as well.
EG:
#!/usr/local/cpython-3.3/bin/python
some = 100
param1 = 1
def func1(param1, function):
param2 = res1 + some;
def func2(param2, function):
pass
func2(param2, function)
Decorators are just syntactic wrappers for "thing that can execute arbitrary code before and after another function." That's what you're doing with a callback, and hey: flat is better than nested.
def func1(fn):
def wrapped(arg):
return fn(arg+1)
return wrapped
def func2(fn):
def wrapped(arg):
return fn(arg+2)
return wrapped
@func1
@func2
def func3(x):
return x + 3
print(func3(1))
#prints 7
