Basically, you check if an object is an instance of a specific class. You normally use it, when you have a reference or parameter to an object that is of a super class or interface type and need to know whether the actual object has some other type (normally more concrete). Example: Note that if … Read more
Let me give some information on them: quit() simply raises the SystemExit exception.Furthermore, if you print it, it will give a message:>>> print (quit) Use quit() or Ctrl-Z plus Return to exit >>> This functionality was included to help people who do not know Python. After all, one of the most likely things a newbie will try to … Read more
git pull origin master pulls the master branch from the remote called origin into your current branch. It only affects your current branch, not your local master branch. It’ll give you history looking something like this: Your local master branch is irrelevant in this. git pull is essentially a combination of git fetch and git merge; it fetches the remote branch then … Read more
For problems where it seems to be an error on a line you think is correct, you can often remove/comment the line where the error appears to be and, if the error moves to the next line, there are two possibilities. Either both lines have a problem or the previous line has a problem which is being carried forward. … Read more
Xpenology isn’t a linux OS like Ubuntu or other common distribution. It’s a bootloader for synologys operating system DSM, which they use on their NAS devices. DSM is running on a custom linux version developed by Synology, so it’s also not real compareable to desktop/server distributions in a direct way. Its optimized for running on … Read more
UNION removes duplicate records (where all columns in the results are the same), UNION ALL does not. There is a performance hit when using UNION instead of UNION ALL, since the database server must do additional work to remove the duplicate rows, but usually you do not want the duplicates (especially when developing reports). UNION Example: Result: UNION ALL example: Result:
SQL Server databases use two files – an MDF file, known as the primary database file, which contains the schema and data, and a LDF file, which contains the logs. See wikipedia. A database may also use secondary database file, which normally uses a .ndf extension. As John S. indicates, these file extensions are purely convention … Read more
There are several differences between HashMap and Hashtable in Java: Hashtable is synchronized, whereas HashMap is not. This makes HashMap better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized ones. Hashtable does not allow null keys or values. HashMap allows one null key and any number of null values. One of HashMap’s subclasses is LinkedHashMap, so in the event that you’d want predictable iteration order (which is insertion order by default), you … Read more
First make sure you have checked the most voted answer. I’m not sure if it’s exactly your problem, but in my case, I wasn’t able to upgrade Django to 1.2.4 – I was always finishing with 1.2.3 version, so I uninstalled Django with: Then I removed <virtualenv>/build/Django directory and finally I installed the proper version with:
Really the ideal way to do this is to not use pull at all, but instead fetch and reset: (Altering master to whatever branch you want to be following.) pull is designed around merging changes together in some way, whereas reset is designed around simply making your local copy match a specific commit. You may want to consider slightly different options to clean depending on your system’s … Read more