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“There was an error while performing this operation”
...e in IIS for which I cannot open any of the settings like Authentication, Handler Mappings, Authorization Rules etc. It just shows the error message "There was an error while performing this operation", with no more details and points to web.config.
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Return type of '?:' (ternary conditional operator)
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Expressions don't have return types, they have a type and - as it's known in the latest C++ standard - a value category.
A conditional expression can be an lvalue or an rvalue. This is its value category. (This is somewhat of a simplification, in C++11 we have lvalues, xvalues a...
What's the difference between detaching a Fragment and removing it?
In the Android docs for a FragmentTransaction I noticed two very similar methods: detach and remove . The descriptions over there don't seem to provide much insight about when to use each, and from what I can tell they appear to be the same.
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Always pass weak reference of self into block in ARC?
...am a little confused about block usage in Objective-C. I currently use ARC and I have quite a lot of blocks in my app, currently always referring to self instead of its weak reference. May that be the cause of these blocks retaining self and keeping it from being dealloced ? The question is, sho...
Swift Beta performance: sorting arrays
I was implementing an algorithm in Swift Beta and noticed that the performance was very poor. After digging deeper I realized that one of the bottlenecks was something as simple as sorting arrays. The relevant part is here:
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What is the difference between id and class in CSS, and when should I use them? [duplicate]
Here I gave an id to the div element and it's applying the relevant CSS for it.
15 Answers
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Eclipse will not start and I haven't changed anything
...aven't updated anything for at least a month. I was just working normally and suddenly the menus were all blank, so I decided to restart eclipse. I clicked "close" and "ok" to save everything, but nothing happened, so I clicked close again and eclipse closed. I clicked on eclipse and the loading sc...
Difference between abstraction and encapsulation?
What is the precise difference between encapsulation and abstraction?
39 Answers
39
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Django migration strategy for renaming a model and relationship fields
...ome errors if you don't update the names where it's imported e.g. admin.py and even older migration files (!).
Update: As ceasaro mentions, newer versions of Django are usually able to detect and ask if a model is renamed. So try manage.py makemigrations first and then check the migration file.
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user authentication libraries for node.js?
...an do password authentication for a user (using a custom backend auth DB), and associate that user with a session.
15 Answe...