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Why covariance and contravariance do not support value type

... 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>...
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How do I purge a linux mail box with huge number of emails? [closed]

... 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. share | ...
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Meaning of “[: too many arguments” error from if [] (square brackets)

... # if [ hello world == 0 ] fi The same will be true for any function call that puts down a string containing spaces or other special characters. Easy fix Wrap the variable output in double quotes, forcing it to stay as one string (therefore one argument). For example, VARIABLE=$(/some/comm...
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How to configure MongoDB Java driver MongoOptions for production use?

... Updated to 2.9 : autoConnectRetry simply means the driver will automatically attempt to reconnect to the server(s) after unexpected disconnects. In production environments you usually want this set to true. connectionsPerHost are the amount of physical connections a single Mongo instance (it's si...
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Coloring white space in git-diff's output

...ght=new,old highlights whitespace errors on both deleted and added lines. all can be used as a short-hand for old,new,context. git diff --ws-error-highlight=new,old <file> or git diff --ws-error-highlight=all <file> I don't know of a way to permanently turn this on and store this...
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Maven parent pom vs modules pom

...ructure (pattern #2): root/ parent-pom/ pom.xml projectA/ Optionally, you can even add a pom.xml in the trunks directory: root |-- parent-pom | |-- branches | |-- tags | `-- trunk | `-- pom.xml |-- projectA | |-- branches | |-- tags | `-- trunk | |-- module1 | ...
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Display string as html in asp.net mvc view

...n I am displaying it on views, it is displayed as simple string containing all tags. I tried to use Html helper to encode/decode to display it properly, but it is not working. ...
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Best Timer for using in a Windows service

...those will cause the service to load an additional assembly which is not really needed for the type of application you are building. Use System.Timers.Timer like the following example (also, make sure that you use a class level variable to prevent garbage collection, as stated in Tim Robinson's ans...
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How to “warm-up” Entity Framework? When does it get “cold”?

... help increase performance. However with EF5 it isn't necessary to compile all your queries since EF will auto-compile queries itself. The only problem is that these queries can get lost when the cache is swept. So you still want to hold references to your own compiled queries for those that are occ...
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In Vim, how do I apply a macro to a set of lines?

...at performs an operation on a single line. I want to repeat that macro on all of the remaining lines in the file. Is there a quick way to do this? ...