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Ruby Metaprogramming: dynamic instance variable names
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You can also use send which prevents the user from setting non-existent instance variables:
def initialize(hash)
hash.each { |key, value| send("#{key}=", value) }
end
Use send when in your class there is a setter like attr_accessor for your instance variables:
clas...
Passing a list of kwargs?
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The ** unpacking operator can be used to pass kwargs from one function to another function's kwargs. Consider this code: (newlines don't seem to be allowed in comments) def a(**kw): print(kw), and def b(**kw): a(kw). This code will generate an error because kwargs is actually a...
Why not abstract fields?
...ub message");
}
String doSomething() {
return errMsg + " from something";
}
}
If your child class "forgets" to initialise the final through the super constructor the compiler will give a warning an error, just like when an abstract method is not implemented.
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Django fix Admin plural
How do I change some models name from "Categorys" to "Categories" on admin site in the new dev django version?
In the old version (whithout admin sites and admin models) you could just do this;
http://www.the-dig.com/blog/post/customize-plural-name-django-admin/
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How to create multiple levels of indentation in Javadoc?
...</ul>
* </ul>
* </ul>
*/
Although JavaDoc borrows from HTML, it isn't HTML, and you should omit the </li> tags, just as you should omit </p> tags.
share
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improv...
while (1) vs. while(True) — Why is there a difference (in python 2 bytecode)?
...f these cases. bool is a subclass of int, and inherits most of its methods from int, and True has an internal integer value of 1. So, whether you're doing a while test (__bool__ in 3.x, __nonzero__ in 2.x), a comparison (__eq__), or arithmetic (__add__), you're calling the same method whether you us...
NameError: global name 'unicode' is not defined - in Python 3
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that doesn't preserve BC like the answer from @atm Please consider retracting or updating your answer. There is no reason to leave python2 users behind or have breaking python3
– MrMesees
Sep 4 '18 at 22:47
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Run a callback only if an attribute has changed in Rails
... on the return value of a method call. The status_id_changed? method comes from ActiveModel::Dirty, which allows us to check if a specific attribute has changed by simply appending _changed? to the attribute name.
When the do_something method should be called is up to your needs. It could be before...
Scala constructor overload?
... constructor (as in landon9720's) answer, or another auxiliary constructor from the same class, as their first action. They cannot simply call the superclass's constructor explicitly or implicitly as they can in Java. This ensures that the primary constructor is the sole point of entry to the class....
Capistrano - clean up old releases
Usually when using capistrano, I will go and manually delete old releases from a deployed application. I understand that you can run cap deploy:cleanup but that still leaves 5 releases. Is this it's intended purpose? Is there another way to cleanup old releases to just 1 previous deploy?
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