I have this function:
def check_if_year(years):
if years.isnumeric():
year = int(years)
How would I recall year in that function to use it outside of the function and into another function? Thanks in advance.
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7 Answers
You should recall that function using return
def check_if_year(years):
if years.isnumeric():
year = int(years)
return year
This returns/recalls year
2 Comments
David Ehrmann
If years might be multiple years in, say, a list, he could be looking to use yield and a generator.
Srivatsan
@DavidEhrmann but his want is to only use year outside the function say as a variable etc..
def check_if_year(years):
if years.isnumeric():
year = int(years)
return year
Comments
You should return from the function:
def check_if_year(years):
if years.isnumeric():
return int(years)
You can then assign year as:
year = check_if_year(somestring)
outside that function.
3 Comments
user3294540
try: file_name_one = input("First file name: ") file_stream = open(file_name_one, "r") for line in file_stream: year_str = line[:4] years = year_str check_if_year(years) year = check_if_year(years) check_leap_year(year) i get an attribute error
user3294540
so i did year = check_if_year(years) then check_leap_year(year) which is my second function but i get an attribute error
jonrsharpe
It would be helpful to provide the full traceback - is
check_leap_year also assuming year will be a string? E.g. do you call isdigit() again?You can return the value of year as input to another funcion.
def check_if_year(years):
if years.isnumeric():
year = int(years)
return year # function returns year
y = check_if_year(years) # Call the check_if_year function and store the result in y
another_function(y) # Pass the return value year to another function
Comments
Your function is actually mostly useless - what are you going to do if year is not numeric anyway ?
The simplest solution is to just try to build an int from whatever year is and handle the exception (how you want to handle it depends on the context) :
try:
year = int(year)
except ValueError as e:
handle_the_problem_one_way_or_another(year, e)
else:
call_some_other_func(year)
answered Feb 19, 2014 at 19:45
bruno desthuilliers
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Comments
def remember_year( year ): # Return a function that 'remembers' the value of year
return lambda x: x + year
plus10 = remember_year( 10 )
print plus10( 5 )
>> 15
Comments
I would propose that EAFP is more Pythonic than the LBYL approach you have:
def check_if_year(years):
try:
return int(years)
except ValueError as e:
print e
# do something with the fact you have a bad date...
Interact this way:
>>> check_if_year('1999')
1999
>>> check_if_year('abc')
invalid literal for int() with base 10: 'abc'
Then if you wanted to 'put inside another function' you could do something like this:
def leap_year(st):
def check_if_year(year):
try:
return int(year)
except ValueError as e:
raise
n=check_if_year(st)
if n % 400 == 0:
return True
if n % 100 == 0:
return False
if n % 4 == 0:
return True
# else
return False
print leap_year('1900') # False
print leap_year('2000') # True
print leap_year('next year') # exception
4 Comments
bruno desthuilliers
your except clause is worse than useless.
dawg
@brunodesthuilliers That is kinda harsh. It is just an ignored
except clause. (Or at least one that only prints the exception as an example.) Who says that an except needs to do anything? It is a simple example to show the OP an alternate way to code a simple function. What would YOU have the except do in this case? It is up to the OP what is to be done with a bad year string.bruno desthuilliers
"Errors should never pass silently." (Zen of Python) - and I've lost days debugging bad code that silently swallowed exceptions or assumed too much about what went wrong exactly. Remember that your answer will be read by a lot of newcomers that may understand it as being a good practice - which it's not. wrt/ "What would I do", it really depends on the context - either let the exception propagate, wrap it into another more specific exception, or something more complex (like in the case of a HTTP form validation), but I would certainly not just print the exception and call it a day.
dawg
@brunodesthuilliers: This is not meant to be production code. It is a simple example of
try/except that the OP can choose to learn more about or not. Since what is to be done with a bad year string is not specified in the original, it makes no sense to specify it here. The second example I added (based on the OP's comments) does exactly what you say it should: die on a bad string.