Question

How does time.localtime() work exactly? I can call up the “array” (tupple, I think it is called – because it is immutable?) and reference/index components of it. For example:

>>> time.localtime()[0]
2010

But if I do:

print time.localtime()
time.struct_time(tm_year=2010, tm_mon=2, tm_mday=7, tm_hour=14, tm_min=46, tm_sec=58, tm_wday=6, tm_yday=38, tm_isdst=0)

First: How does time.localtime() know to return time.struct_time()?

Second: If I type print time.struct_time() it wants additional values to be passed to it (thus not giving me the same values it returned from time.localtime()) – how do I know what those values could possibly be? I checked the python documentation and I couldn’t make ‘heads nor tails’ of it. Really just looking for an example here…

Third: When I index the tupple/array for time.localtime() it returns the proper associated value, “2010” for example, rather than “tm_year=2010” – how does it know to do this (generally speaking not asking for a lot here).

Forth: If I wanted to “call” tm_year from time.localtime() how can I do this? What I am doing (and don’t ‘feel’ right about) is the following:

tm_year = str(time.localtime()[0])
tm_mon = str(time.localtime()[1])
tm_mday = str(time.localtime()[2])
tm_hour = str(time.localtime()[3])
tm_min = str(time.localtime()[4])

NOTE: I am saving them as strings for other reasons not explained in this question, just wanted to point out that I am creating my own variables (named exactly the same as they are in the tupple) and then just referencing the index value associated with the value I want

Is there a way to to just call time.localtime(tm_year) (I know that doesn’t work as is, but just brainstorming…)

Thanks in advance… (and I have read “http://docs.python.org/library/time.html” but I am sure I missed some important information… any advice?)

-J

Answer 1

time.localtime()[0] calls __gettiem__() on the time.struct_time instance. This is how it gets this list/tuple like behaviour from. Here is a really simple example

>>> class MyTime(object):
...     def __init__(self, year, month, mday, hour, minute):
...         self.data =  year, month, mday, hour, minute
...     def __getitem__(self, idx):
...         return self.data[idx]
...     def __str__(self):
...         return "MyTime(tm_year=%s, tm_mon=%s, tm_mday=%s, tm_hour=%s, tm_min=%s)"%self.data
... 
>>> x=MyTime(2010,2,7,14,46)
>>> x[0]
2010
>>> x[1]
2
>>> print x
MyTime(tm_year=2010, tm_mon=2, tm_mday=7, tm_hour=14, tm_min=46)

time.struct_time is a class. time.localtime() returns an instance of the class, which explains the difference when you try to print them

You can load up your 5 variables like this

>>> tm_year,tm_mon,tm_mday,tm_hour,tm_min=map(str,time.localtime()[:5])