Is it possible in python to write a lambda function that does not need any parameters passed to it? For instance, is there a way to translate this function:
def file_opener():
f = open('filename.txt').read()
return f
or any other function with no passed input into a lambda expression?
You certainly can do it..
x = lambda : 6
print(x()) # prints -> 6
You probably shouldn't though. Once you feel the need to bind a function to a variable name you should go the long road instead (def ..) as you do it in your example.
lambda. They are used to write anonymous functions. Once you assign them to a variable, you should have used def.Try this (Recommended as no hard-coding is present):
file = lambda f: open(f).read()
print (file('open.txt'))
If you don't want to pass filename as an argument then use this:
f = lambda: open('open.txt').read()
print (f())
f).
lambda to a variable completely invalidates the reason for having lambdas in the first place. lambda is used to write anonymous functions. If you want a named function, use def. This may just be a toy example but do we really need another example of improper use of lambda?Just try it!
>>> open('filename.txt', 'w').write('this is filename.txt contents')
29
>>> def call_this(fctn):
... return fctn()
...
>>> print(call_this(lambda: open('filename.txt').read()))
this is filename.txt contents
It works
