As of TypeScript 4.1, you can use a template literal type for this. type StartsWithPrefix = `prefix${string}`; This works for type unions as well: // `abc${string}` | `def${string}` type UnionExample = `${‘abc’ | ‘def’}${string}`; // For your example: type MyPrefixTypes = `${MyStringTypes}${string}`; const ok: UnionExample=”abc123″; const alsoOk: UnionExample=”def123″; const notOk: UnionExample=”abdxyz”; // Note that a … Read more
if I’m checking what should ALWAYS BE A BASE OBJECT, what do I really lose from doing type is? well, it’s nice you give the full documented answer in your question, so your answer is you lose nothing! The only times where isinstance() is necessary is when checking inheritance of a given class compared to … Read more
No need to import modules, isinstance(), str and unicode (versions before 3 — there’s no unicode in 3!) will do the job for you. Python 2.x: Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type “help”, “copyright”, “credits” or “license” for more information. >>> isinstance(u”, (str, unicode)) True … Read more
In Python 3.8 and later, the approach suggested by MSeifert and Richard Xia can be improved by not using the undocumented attributes __origin__ and __args__. This functionality is provided by the new functions typing.get_args(tp) and typing.get_origin(tp): >> from typing import Union, get_origin, get_args >> x = Union[int, str] >> get_origin(x), get_args(x) (typing.Union, (<class ‘int’>, <class … Read more
You can use inspect.getmembers to get all the classes in your module: inspect.getmembers(my_module,inspect.isclass) This will return a list of name-class pairs. You just want the classes: my_module_classes = tuple(x[1] for x in inspect.getmembers(my_module,inspect.isclass)) One thing that I managed to overlook when I initially wrote this answer is the ability to check a class’s __module__ attribute. … Read more
There are two ways that you can do this. First, you can use the typeid operator, which returns a type_info structure containing information about the type of the object. For example: Base* ptr = /* … */ if (typeid(*ptr) == typeid(DerivedType)) { /* … ptr points to a DerivedType … */ } Notice that you … Read more
Now i am assigning a variable with this enum like this a = TransactionTypes I hope you aren’t, because what you just assigned to a is the entire enumeration, not one of its members (such as TransactionTypes.chargeback) If that is really what you wanted to do, then the correct test would be: if issubclass(a, enum.Enum) … Read more
I upvoted Matt Joiner’s answer, but wanted to include some additional observations to make it clear that, along with a couple of other factors, there are 4 times that matter when choosing between pre-checking conditions (known as LBYL or “Look Before You Leap”) and just handling exceptions (known as EAFP or “Easier to Ask Forgiveness … Read more