python default configuration reuse of variables

Question

class DefaultConfig(object):
    class S3(object):
        DATA_ROOT = 's3://%(bucket_name)s/NAS'
        DATA_LOCATION = '{}/%(instrument_id)s/%(run_id)s'.format(DefaultConfig.S3.DATA_ROOT)

The code above gives me the following error.

      File "./s3Utils.py", line 5, in <module>
    from InfraConfig import InfraConfig as IC
  File "/opt/src/datasource/src/main/python/util/InfraConfig.py", line 4, in <module>
    class DefaultConfig(object):
  File "/opt/src/datasource/src/main/python/util/InfraConfig.py", line 6, in DefaultConfig
    class S3(object):
  File "/opt/src/datasource/src/main/python/util/InfraConfig.py", line 14, in S3
    DATA_LOCATION = '{}/%(instrument_id)s/%(run_id)s'.format(DefaultConfig.S3.DATA_ROOT)
NameError: name 'DefaultConfig' is not defined

Why is it unable to find DefaultConfig.S3.DATA_ROOT Also, this is my attempt at writing structured configuration with reuse of values of DefaultConfig. Is there a way to do this without writing a yml file?

@ŁukaszRogalski: This actually is an MCVE.

user2357112
– user2357112

2016-09-15 19:04:58 +00:00
Commented Sep 15, 2016 at 19:04 — user2357112
– user2357112, Commented Sep 15, 2016 at 19:04
@user2357112 yep, I misread and misinterpreted the question

Łukasz Rogalski
– Łukasz Rogalski

2016-09-15 19:32:06 +00:00
Commented Sep 15, 2016 at 19:32 — Łukasz Rogalski
– Łukasz Rogalski, Commented Sep 15, 2016 at 19:32

FunkySayu · Accepted Answer · 2016-09-15 19:03:38Z

2

It is unable to find the DefaultConfing because DefaultConfig is not defined at the moment S3 is created.

Remember that class are objects. Because there are objects, that means they need to be instantiate. Python instantiate a class at the end of its definition, and therefore register it in the globals. Because the class definition is not finished, you can't use the DefaultConfig name.

answered Sep 15, 2016 at 19:03

FunkySayu

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Comments

Jimilian · Accepted Answer · 2016-09-15 19:12:45Z

1

You should use it without any prefixes:

class DefaultConfig(object):
  class S3(object):
    DATA_ROOT = 's3://%(bucket_name)s/NAS'
    DATA_LOCATION = '{}/%(instrument_id)s/%(run_id)s'.format(DATA_ROOT)

 print DefaultConfig.S3.DATA_LOCATION

returns:

> s3://%(bucket_name)s/NAS/%(instrument_id)s/%(run_id)s

edited Sep 15, 2016 at 19:12

answered Sep 15, 2016 at 19:01

Jimilian

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