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What are some (concrete) use-cases for metaclasses?
... B(A):
... pass
...
>>> models
{'A': <__main__.A class at 0x...>,
'B': <__main__.B class at 0x...>}
This can also be done with class decorators:
models = {}
def model(cls):
models[cls.__name__] = cls
return cls
@model
class A(object):
pass
Or with an expl...
How to join two generators in Python?
....chain() does not return a types.GeneratorType instance. Just in case the exact type is crucial.
– Riga
Sep 16 '19 at 13:45
...
Get a list of distinct values in List
...
Notes.Select(x => x.Author).Distinct();
This will return a sequence (IEnumerable<string>) of Author values -- one per unique value.
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Monad in plain English? (For the OOP programmer with no FP background)
...stem which lets you take a type and turn it into a more special type. For example, in C# consider Nullable<T>. This is an amplifier of types. It lets you take a type, say int, and add a new capability to that type, namely, that now it can be null when it couldn't before.
As a second example, ...
multiple prints on the same line in Python
...can use the print statement to do this without importing sys.
def install_xxx():
print "Installing XXX... ",
install_xxx()
print "[DONE]"
The comma on the end of the print line prevents print from issuing a new line (you should note that there will be an extra space at the end of the out...
Turn a string into a valid filename?
...look at the Django framework for how they create a "slug" from arbitrary text. A slug is URL- and filename- friendly.
The Django text utils define a function, slugify(), that's probably the gold standard for this kind of thing. Essentially, their code is the following.
def slugify(value):
""...
Canvas width and height in HTML5
Is it possible to fix the width and height of an HTML5 canvas element?
4 Answers
4
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__getattr__ on a module
...ibute__. Dunder methods had previously worked on modules - you could, for example, use a module as a context manager simply by defining __enter__ and __exit__, before those tricks broke.
Recently some historical features have made a comeback, the module __getattr__ among them, and so the existing ...
How can I post data as form data instead of a request payload?
...he code below, the AngularJS $http method calls the URL, and submits the xsrf object as a "Request Payload" (as described in the Chrome debugger network tab). The jQuery $.ajax method does the same call, but submits xsrf as "Form Data".
...
Where can I find “make” program for Mac OS X Lion?
Just upgraded my computer to Mac OS X Lion and went to terminal and typed "make" but it says:
-bash: make: command not found
...