python Programming Glossary: sentinel

Why is if not someobj: better than if someobj == None: in Python?

http://stackoverflow.com/questions/100732/why-is-if-not-someobj-better-than-if-someobj-none-in-python

two numbers ... and to check for identity only when using sentinel values None meaning not initialized for a member field for exemple..

Call exiftool from a python script?

http://stackoverflow.com/questions/10075115/call-exiftool-from-a-python-script

subprocess import os import json class ExifTool object sentinel ready n def __init__ self executable usr bin exiftool self.executable.. self.process.stdout.fileno while not output.endswith self.sentinel output os.read fd 4096 return output len self.sentinel def get_metadata.. output os.read fd 4096 return output len self.sentinel def get_metadata self filenames return json.loads self.execute..

python - returning a default value

http://stackoverflow.com/questions/12265695/python-returning-a-default-value

value share improve this question You need to use a sentinel to detect that a default value was not set sentinel object def.. use a sentinel to detect that a default value was not set sentinel object def func someparam default sentinel if default is not.. was not set sentinel object def func someparam default sentinel if default is not sentinel print You passed in something else..

default value of parameter as result of instance method

http://stackoverflow.com/questions/13075044/default-value-of-parameter-as-result-of-instance-method

The common idiom here is to set the default to some sentinel value None is typical although some have suggested Ellipsis.. You might also see an instance of object used for the sentinel. SENTINEL object class Example object def __init__ self data..

How to get/set local variables of a function (from outside) in Python?

http://stackoverflow.com/questions/1360721/how-to-get-set-local-variables-of-a-function-from-outside-in-python

know which constant in co.co_consts is which this uses a sentinel value to figure it out. Depending on whether you can constrain..

file.tell() inconsistency

http://stackoverflow.com/questions/14145082/file-tell-inconsistency

f.readline '' print f.tell This uses the iter function sentinel argument to turn any callable into an iterator. share improve..

Finding a key recursively in a dictionary

http://stackoverflow.com/questions/14962485/finding-a-key-recursively-in-a-dictionary

any of your dictionaries. In that case you could set up a sentinel object for this function and return that in the case that you.. you don't find anything Then you can check against the sentinel to know if you found something or not. share improve this answer..

interleaving 2 lists of unequal lengths [duplicate]

http://stackoverflow.com/questions/19883826/interleaving-2-lists-of-unequal-lengths

'no' 'yes' 'why' Using roundrobin recipe from itertools no sentinel value required here from itertools import def roundrobin iterables..

Reading Huge File in Python

http://stackoverflow.com/questions/744256/reading-huge-file-in-python

a sorted list of the keys we need to lookup # there is a sentinel at the end of list to simplify the code # we use pointer to.. 1 if pointer len list 1 break # end of list 1 is due to sentinel Coded binary search seek solution thanks kigurai entries 24935502..

Multiple writes get handled as single one

http://stackoverflow.com/questions/9959616/multiple-writes-get-handled-as-single-one

of the message then the message. Separate messages with a sentinel byte. Here's an example of a class to buffer received data using.. an example of a class to buffer received data using a sentinel byte import socket class Client object def __init__ self self.buffer.. def get_msg self '''Append raw data to buffer until sentinel is found then strip off the message leaving the remainder in..

How to create a generator/iterator with the Python C API?

http://stackoverflow.com/questions/1815812/how-to-create-a-generator-iterator-with-the-python-c-api

max T_UINT offsetof SequenceObject max 0 NULL NULL Sentinel static int Sequence_Init SequenceObject self PyObject args PyObject.. object n Returns iterator of range 0 sequence.max . NULL Sentinel Define new object type PyTypeObject Sequence_Type PyObject_HEAD_INIT.. NULL next PyCFunction Generator_next METH_NOARGS NULL NULL Sentinel static void Generator_dealloc GenericEventObject self if self..

python Pool with worker Processes

http://stackoverflow.com/questions/9038711/python-pool-with-worker-processes

for data in the_real_source request_queue.put data # Sentinel objects to allow clean shutdown 1 per worker. for i in range..