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what is the difference between a portlet and a servlet?
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Portlets are part of JSR-168 standard that regulates portal containers and components. This is different standard from standards for web containers (and servlets). Though there are definitely strong parallels between these two standards they differ in containers, APIs, l...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
When using summarise with plyr 's ddply function, empty categories are dropped by default. You can change this behavior by adding .drop = FALSE . However, this doesn't work when using summarise with dplyr . Is there another way to keep empty categories in the result?
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Boolean operators && and ||
According to the R language definition , the difference between & and && (correspondingly | and || ) is that the former is vectorized while the latter is not.
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Difference between Pragma and Cache-Control headers?
I read about Pragma header on Wikipedia which says:
3 Answers
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Using -performSelector: vs. just calling the method
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Basically performSelector allows you to dynamically determine which selector to call a selector on the given object. In other words the selector need not be determined before runtime.
Thus even though these are equivalent:
[anObject aMethod];
[anObject p...
Is it bad practice to have a constructor function return a Promise?
I'm trying to create a constructor for a blogging platform and it has many async operations going on inside. These range from grabbing the posts from directories, parsing them, sending them through template engines, etc.
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Difference between Grunt, NPM and Bower ( package.json vs bower.json )
I'm new to using npm and bower, building my first app in emberjs :).
I do have a bit of experience with rails, so I'm familiar with the idea of files for listing dependencies (such as bundler Gemfile)
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What is the recommended approach towards multi-tenant databases in MongoDB?
I'm thinking of creating a multi-tenant app using MongoDB. I don't have any guesses in terms of how many tenants I'd have yet, but I would like to be able to scale into the thousands.
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How can I assign an ID to a view programmatically?
...a view like android:id="@+id/something" and then call findViewById() , but when creating a view programmatically, how do I assign an ID?
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Looking for a clear definition of what a “tokenizer”, “parser” and...
...nd "lexer" are and how they are related to each other (e.g., does a parser use a tokenizer or vice versa)? I need to create a program will go through c/h source files to extract data declaration and definitions.
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