A lock allows only one thread to enter the part that’s locked and the lock is not shared with any other processes. A mutex is the same as a lock but it can be system wide (shared by multiple processes). A semaphore does the same as a mutex but allows x number of threads to enter, this … Read more
I had this problem with a Crowduino, running the Arduino IDE on OS X. The solution for me was to switch on verbose output during upload (in the Arduino IDE preferences pane). Then, when uploading, you can see AVRDUDE sending three packets avrdude: Send: 0 [30] [20] (with corresponding RX flashes on the board) right before the avrdude: ser_recv(): programmer is … Read more
Why not just do sudo easy_install pip or if this is for python 2.6 sudo easy_install-2.6 pip? This installs pip using the default python package installer system and saves you the hassle of manual set-up all at the same time. This will allow you to then run the pip command for python package installation as it will be installed with … Read more
It means the value of data is None.
TL;DR: You can’t do relative imports from the file you execute since __main__ module is not a part of a package. Absolute imports – import something available on sys.path Relative imports – import something relative to the current module, must be a part of a package If you’re running both variants in exactly the same way, one of them should work. Here is … Read more
Update: Data Classes With the introduction of Data Classes in Python 3.7 we get very close. The following example is similar to the NamedTuple example below, but the resulting object is mutable and it allows for default values. This plays nicely with the new typing module in case you want to use more specific type annotations. I’ve been waiting desperately for this! If you ask … Read more
The benefits of super() in single-inheritance are minimal — mostly, you don’t have to hard-code the name of the base class into every method that uses its parent methods. However, it’s almost impossible to use multiple-inheritance without super(). This includes common idioms like mixins, interfaces, abstract classes, etc. This extends to code that later extends yours. If somebody … Read more
It means, essentially, what it says; that ‘this is important, ignore subsequent rules, and any usual specificity issues, apply this rule!’ In normal use a rule defined in an external stylesheet is overruled by a style defined in the head of the document, which, in turn, is overruled by an in-line style within the element itself (assuming equal specificity … Read more
A pointer can be re-assigned:int x = 5; int y = 6; int *p; p = &x; p = &y; *p = 10; assert(x == 5); assert(y == 10); A reference cannot be re-bound, and must be bound at initialization:int x = 5; int y = 6; int &q; // error int &r = x; … Read more
Redoc is a React app which means the actual HTML is being built in runtime: first the skeleton of the page loads, which also loads redoc javascript then the Redoc downloads the OpenAPI json (or yaml) file and renders the actual HTML dynamically based on it This is similar for many apps build with modern JS … Read more