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Rails migrations: self.up and self.down versus change
... For example, in your case what is the reverse operation of add_column to call when you rollback? Of course it's remove_column. What is the inverse of create_table? It's drop_table. So in these cases rails know how to rollback and define a down method is superfluous (you can see in the documentation...
How can I keep my fork in sync without adding a separate remote?
...:
There isn't anything to compare.
someone:master is up to date with all commits from me:master. Try switching the base for your comparison.
Click on switching the base on this page:
Then you get to see all the commits made to someone/foobar after the day you forked it.
Click on Create p...
Logging levels - Logback - rule-of-thumb to assign log levels
...y requires human intervention. The "2AM rule" applies here- if you're on call, do you want to be woken up at 2AM if this condition happens? If yes, then log it as "error".
warn: an unexpected technical or business event happened, customers may be affected, but probably no immediate human intervent...
What does an exclamation mark mean in the Swift language?
...pple have chosen to declare the types as implicitly unwrapped, making the calling code more convenient, but less safe.
Perhaps Apple might comb through their frameworks in the future, removing the uncertainty of implicitly unwrapped ("probably never nil") parameters and replacing them with optional...
From inside of a Docker container, how do I connect to the localhost of the machine?
...as described in qoomon's answer.
2020-01: some progress has been made. If all goes well, this should land in Docker 20.04
TLDR
Use --network="host" in your docker run command, then 127.0.0.1 in your docker container will point to your docker host.
Note: This mode only works on Docker for Linux...
How to hide databases that I am not allowed to access
... I connect to my Heroku - Postgresql database via pgAdmin3 , It lists all the tables (about 2600). Every time I open the pgAdmin3 I have to find my own database.
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How to detect if a property exists on an ExpandoObject?
...a dynamic invocation, with the case you get in the internals. More specifically, it is explicitly implemented: github.com/mono/mono/blob/master/mcs/class/dlr/Runtime/…
– Dykam
Feb 4 '15 at 18:04
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Why are nested weights bad for performance? Alternatives?
...with non-zero weights, then the number of measurements
increase exponentially.
It's better to use RelativeLayouts and adjust your view according to the places of other views without using specific dpi values.
share
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Hidden features of Python [closed]
...ue, and then comparing True < 10, which is also True, then no, that's really not what happens (see the last example.) It's really translating into 1 < x and x < 10, and x < 10 and 10 < x * 10 and x*10 < 100, but with less typing and each term is only evaluated once.
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Calendar Recurring/Repeating Events - Best Storage Method
... didn't want to have a large number of rows, and I wanted to easily lookup all events that would take place on a specific date.
The method below is great at storing repeating information that occurs at regular intervals, such as every day, every n days, every week, every month every year, etc etc. ...