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What is the main difference between Inheritance and Polymorphism?
...class, then you have a Student class that extends Person, Student inherits all the things that Person has. There are some details around the access modifiers you put on the fields/methods in Person, but that's the basic idea. For example, if you have a private field on Person, Student won't see it...
In plain English, what does “git reset” do?
...master)
You've ended up in a detached HEAD state. HEAD, work tree, index all match B, but the master branch was left behind at C. If you make a new commit D at this point, you'll get this, which is probably not what you want:
- A - B - C (master)
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D (HEAD)
Remember, reset doesn'...
Metadata file '.dll' could not be found
...idn't solve issue so I've had to do next steps: - clean solution - uncheck all build checkboxes - restart VS - check all build checkboxes - build solution
– frankie
Apr 8 '14 at 9:54
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Java concurrency: Countdown latch vs Cyclic barrier
...ble task which is run once the common barrier condition is met.
It also allows you to get the number of clients waiting at the barrier and the number required to trigger the barrier. Once triggered the barrier is reset and can be used again.
For simple use cases - services starting etc... a C...
Rails 3: I want to list all paths defined in my rails application
I want to list all defined helper path functions (that are created from routes) in my rails 3 application, if that is possible.
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Reset the database (purge all), then seed a database
... the whole shebang just to reload your data, you could use MyModel.destroy_all (or delete_all) in the seed.db file to clean out a table before your MyModel.create!(...) statements load the data. Then, you can redo the db:seed operation over and over. (Obviously, this only affects the tables you've...
MySQL: Fastest way to count number of rows
...olumn indexes, so it will be the best result. Mysql with MyISAM engine actually stores row count, it doensn't count all rows each time you try to count all rows. (based on primary key's column)
Using PHP to count rows is not very smart, because you have to send data from mysql to php. Why do it whe...
How do I purge a linux mail box with huge number of emails? [closed]
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You can simply delete the /var/mail/username file to delete all emails for a specific user. Also, emails that are outgoing but have not yet been sent will be stored in /var/spool/mqueue.
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Is there an S3 policy for limiting access to only see/access one bucket?
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I've been trying this for a while and finally came up with a working solution. You must use different "Resources" depending on the kind of action you're performing. Also I included some missing actions in the previous answer (like DeleteObject) and restricting some ...
biggest integer that can be stored in a double
... do you want?
Go on, ask me what the largest integer is, such that it and all smaller integers can be stored in IEEE 64-bit doubles without losing precision. An IEEE 64-bit double has 52 bits of mantissa, so I think it's 253:
253 + 1 cannot be stored, because the 1 at the start and the 1 at the e...