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MySQL Error 1215: Cannot add foreign key constraint
... @www.jensolsson.se You are correct, if the PK includes one or more string columns then they must use the same character set and collation. In this specific case the PK was an INT so the character set of the table and/or columns was not relevant.
– Ike Walker
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Renaming a virtualenv folder without breaking it
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You need to adjust your install to use relative paths. virtualenv provides for this with the --relocatable option. From the docs:
Normally environments are tied to a
specific path. That means that you
cannot move an environment around or
copy ...
Hadoop “Unable to load native-hadoop library for your platform” warning
...e native Hadoop library $HADOOP_HOME/lib/native/libhadoop.so.1.0.0 was actually compiled on 32 bit.
Anyway, it's just a warning, and won't impact Hadoop's functionalities.
Here is the way if you do want to eliminate this warning, download the source code of Hadoop and recompile libhadoop.so.1.0....
How do you default a new class to public when creating it in Visual Studio?
...1033.
Visual Studio 2010 (10.0) and below: There is a zip file in there called Class.zip. Unpack this, edit the file to put in your public keyword then re-pack it (make sure you backup the original).
After this, make sure VS rebuilds it's cache (which is just the zipfiles unzipped into directorie...
Vagrant error : Failed to mount folders in Linux guest
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The plugin vagrant-vbguest solved my problem:
$ vagrant plugin install vagrant-vbguest
Output:
$ vagrant reload
==> default: Attempting graceful shutdown of VM...
...
==> default: Machine booted and ready!
GuestAdditions 4.3.12 running --- OK.
==> default: Checking for guest addi...
What is the curiously recurring template pattern (CRTP)?
... curiously recurring, isn't it? :)
Now, what does this give you? This actually gives the X template the ability to be a base class for its specializations.
For example, you could make a generic singleton class (simplified version) like this
template <class ActualClass>
class Singleton
{
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Iterating over each line of ls -l output
... instead of parsing output of "ls -l" line by line, you could iterate over all files and do an "ls -l" for each individual file like this:
for x in * ; do echo `ls -ld $x` ; done
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How can I find the current OS in Python? [duplicate]
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I usually use sys.platform (docs) to get the platform. sys.platform will distinguish between linux, other unixes, and OS X, while os.name is "posix" for all of them.
For much more detailed information, use the platform module. Th...
What is __main__.py?
...hat is the __main__.py file for, what sort of code should I put into it, and when should I have one?
5 Answers
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Standardize data columns in R
I have a dataset called spam which contains 58 columns and approximately 3500 rows of data related to spam messages.
15 ...