Which is not how Stack Overflow is meant to work; it is not a dialogue forum. That said "extract a subset" sounds to me similar to a pretty strange way to explain the whole process of working out which aspects of a list meet a problem.
When the answer from Niklas B. is very in depth, when we wish to locate an product in an inventory it is sometimes practical for getting its index:
In git revert -m, the -m alternative specifies the father or mother selection. This is required since a merge commit has more than one mother or father, and Git would not know instantly which parent was the mainline, and which mother or father was the department you need to un-merge.
For those who merge the updated aspect branch (with D at its tip), none of the adjustments manufactured in A or B will likely be in the result, since they had been reverted by W. Which is what Alan observed.
Essentially it's When you've got a condition with is shared throughout multiple threads and prior to the to start with execution with a provided state is concluded, another execution commences and the new thread’s Original state for a specified Procedure is Incorrect since the earlier execution has not done.
– jstine Commented Sep 28, 2015 at fifteen:38 The challenge with this technique, is usually that if you have a vital bit of code with regards to the file not present, Placing it in the besides: clause will make that an exception arising During this element within your code will elevate a complicated message (second error lifted in the course of the processing of the first a single.)
This is certainly very true because it's the one response which states this REALLY IMPORTANT proven fact that I by no means realized ahead of: "you will find three distinct branches to delete!" I'd no idea! This all makes so a lot more perception now, and it sheds a great deal of mild on all one other responses here now far too. Thanks!
Now out there since Python three.4, import and instantiate a Route item Together with the file identify, and Test the is_file approach (Be aware this returns Accurate for symlinks pointing to normal files likewise):
If you are on Python 2, you'll be able to backport the pathlib module from pypi, pathlib2, or in any other case Test isfile from the os.path module:
Consequently, you'll have seven in link "ai". Though you did two steps, however the the two Procedure confirm the exact same thread and no-one other thread will interfere to this, Which means no race ailments! Share Improve this response Abide by
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The C4 commit is in master branch read more and we need to revert to that, that may be mum or dad 1 and -m 1 is needed here (use git log C4 to verify the former commits to substantiate mother or father branch).
The point being, y can be 10, or it could be anything, dependant upon whether or not Yet another thread modified x in between the Examine and act. You don't have any serious method of being aware of.
A race problem occurs when two threads obtain a shared variable simultaneously. The very first thread reads the variable, and the 2nd thread reads the exact same worth in the variable. Then check here the first thread and 2nd thread carry out their functions on the value, they usually race to view which thread can compose the worth previous to the shared variable.