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Why covariance and contravariance do not support value type
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Basically, variance applies when the CLR can ensure that it doesn't need to make any representational change to the values. References all look the same - so you can use an IEnumerable<string> as an IEnumerable<object>...
Replace words in a string - Ruby
...eplaced word isn't in the sentence (the []= variant will).
How to replace all instances?
The above replaces only the first instance of "Robert".
To replace all instances use gsub/gsub! (ie. "global substitution"):
sentence.gsub! 'Robert', 'Joe'
The above will replace all instances of Robert w...
C# short/long/int literal format?
... // uint
var ul = 1UL; // ulong
var l = 1L; // long
I think that's all... there are no literal specifiers for short/ushort/byte/sbyte
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Git pull after forced update
... the working tree since <commit> are discarded.
If you want to actually keep whatever changes you've got locally - do a --soft reset instead. Which will update the commit history for the branch, but not change any files in the working directory (and you can then commit them).
Rebase
You ca...
innerText vs innerHTML vs label vs text vs textContent vs outerText
... a couple of differences:
Note that while textContent gets the content of all elements, including <script> and <style> elements, the mostly equivalent IE-specific property, innerText, does not.
innerText is also aware of style and will not return the text of hidden elements, whereas te...
Understanding keystore, certificates and alias
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The dev site suggests using the same certificate for all your apps. So does this mean, as long as I'm using the same keystore, I can use any alias with any password and it won't mess up updates, as it's just a reference? The actual keystore is the important part?
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JPA or JDBC, how are they different?
...sh for the same. I saw some examples and also read the Oracle docs to know all about Java EE 5. Connecting to a database was very simple. I opened a dynamic web project, created a session EJB , I used EntityManager and with the get methods could access the stored data table.
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Converting an array of objects to ActiveRecord::Relation
I have an array of objects, let's call it an Indicator . I want to run Indicator class methods (those of the def self.subjects variety, scopes, etc) on this array. The only way I know to run class methods on a group of objects is to have them be an ActiveRecord::Relation. So I end up resorting to...
SQLAlchemy: What's the difference between flush() and commit()?
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A Session object is basically an ongoing transaction of changes to a database (update, insert, delete). These operations aren't persisted to the database until they are committed (if your program aborts for some reason in mid-session transaction, any...
Git remote branch deleted, but still it appears in 'branch -a'
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git remote prune origin, as suggested in the other answer, will remove all such stale branches. That's probably what you'd want in most cases, but if you want to just remove that particular remote-tracking branch, you should do:
git branch -d -r origin/coolbranch
(The -r is easy to forget...)...