In my program I want to import simplejson or json based on OS being Linux or Windows. I take the OS name as input from the user. Now, is it correct to do it with a condition like this?
osys = raw_input("Press l for linux, w for Windows:")
if (osys == "w"):
import json as simplejson
else:
import simplejson
I've seen this idiom used a lot, so you don't even have to do OS sniffing:
try:
import json
except ImportError:
import simplejson as json
simplejson as json as it is likely a newer (faster) version of the standard json module.
ujson for speedTo answer the question in your title but not the particular case you provide, it's perfectly correct, tons of packages do this. It's probably better to figure out the OS yourself instead of relying on the user; here's pySerial doing it as an example.
import sys
if sys.platform == 'cli':
from serial.serialcli import Serial
else:
import os
# chose an implementation, depending on os
if os.name == 'nt': # sys.platform == 'win32':
from serial.serialwin32 import Serial
elif os.name == 'posix':
from serial.serialposix import Serial, PosixPollSerial, VTIMESerial # noqa
elif os.name == 'java':
from serial.serialjava import Serial
else:
raise ImportError(
"Sorry: no implementation for your platform ('{}') available".format(
os.name
)
)
This should be only used in cases where you're assuming and need a strong guarantee that certain interfaces/features will be there: e.g. a 'file' called /dev/ttyX. In your case: dealing with JSON, there's nothing that is actually OS-specific and you are only checking if the package exists or not. In that case, just try to import it, and fall-back with an except if it fails:
try:
import some_specific_json_module as json
except ImportError:
import json
simplejson or json is available. You're quoting code from inherently OS-specific imports, which is a very different case. See Matt's answer for the correct approach.
json package and was trying to answer the more general "can you do conditional imports of modules" question.It is not advisable to use to bind json or simplejson with OS platform. simplejson is newer and advanced version of json so we should try to import it first.
Based on python version you can try below way to import json or simplejson
import sys
if sys.version_info > (2, 7):
import simplejson as json
else:
import json
platform.platform()orplatform.system()should do what you need, rather than having a user have to input something every time the code is run.jsonandsimplejson.jsonis in the standard library since 2.6;simplejsonis a third-party library. The reasons to look forsimplejsonare because it's needed (older Python version) or preferred (consciously installed by the user to take advantage of extra functionality). Whether or notsimplejsonis available, has nothing to do with the operating system.