Why Does pytz Assign a 7-Hour, 37-Minute Offset to Asia/Hong_Kong?

Pytz Timezone Enigma: Unraveling the 7-Hour Offset Mystery

In the realm of timezone handling, pytz often takes the lead. However, some users have encountered an unexpected anomaly when working with the 'Asia/Hong_Kong' timezone: why does pytz assign it an unusual 7-hour and 37-minute offset?

Further investigation reveals intriguing observations:

import pytz
pytz.timezone('Asia/Hong_Kong')
# Outputs: <DstTzInfo 'Asia/Hong_Kong' LMT+7:37:00 STD>

Curiously, this offset doesn't seem accurate. However, the following code snippet uncovers a more perplexing discrepancy:

import pytz
from datetime import datetime
hk = pytz.timezone('Asia/Hong_Kong')

dt1 = datetime(2012,1,1,tzinfo=hk)
dt2 = hk.localize(datetime(2012,1,1))
if dt1 > dt2:
   print "Why?"

This code surprisingly prints "Why?", insinuating that dt1 is greater than dt2. What could be the underlying cause behind these peculiar behaviors?

Decoding the Enigma: A Historical Twist

Unraveling this timezone enigma requires a meticulous examination of timezone history. The default timezone and offset extracted by pytz are based on the earliest known records, which can sometimes deviate from current norms. When localized via localize, the proper timezone name and offset are appropriately assigned.

In the case of 'Asia/Hong_Kong,' its earliest recorded offset was indeed 7 hours and 37 minutes (LMT 7:37:00). However, this offset has since been modified. Simply initializing a datetime object with the timezone information (dt1) doesn't allow for automatic adjustment.

Resolving the Anomalous Behavior:

To resolve this discrepancy, it's recommended to rely on the localize method to correctly assign timezone information to datetime objects. By explicitly using localize, pytz ensures the utilization of the appropriate timezone name and offset, reflecting the current timekeeping conventions.

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