There is no final equivalent in Python. To create read-only fields of class instances, you can use the property function, or you could do something like this: class WriteOnceReadWhenever: def __setattr__(self, attr, value): if hasattr(self, attr): raise Exception(“Attempting to alter read-only value”) self.__dict__[attr] = value Also note that while there’s @typing.final as of Python 3.8 … Read more
No difference. They both have the same effect (In the browser, where window is the global context1). window.foo = “bar” sets the property foo on window. foo = “bar” indicates either a typo or intentionally global. Since I have to double check whether it’s a typo or not, I personally find it more readable to … Read more
Something the blog post noted in the comments doesn’t make explicit, but I find to be very important, is that [ThreadStatic] doesn’t automatically initialize things for every thread. For example, say you have this: [ThreadStatic] private static int Foo = 42; The first thread that uses this will see Foo initialized to 42. But subsequent … Read more
There are built-in functions called getattr and setattr getattr(object, attrname) setattr(object, attrname, value) In this case x = getattr(t, ‘attr1’) setattr(t, ‘attr1’, 21)
Try hasattr(): if hasattr(a, ‘property’): a.property See zweiterlinde’s answer below, who offers good advice about asking forgiveness! A very pythonic approach! The general practice in python is that, if the property is likely to be there most of the time, simply call it and either let the exception propagate, or trap it with a try/except … Read more
There is no functional difference. It’s a question of convenience and style. Most often, I tend to see attributes on their own lines as a way to keep them separate and easy to read. It’s also nice to be able to use the line comment // to remove attributes individually. [A] [B] //[C] disabled public … Read more
This concept is used in MVC web applications. The .NET Framework 4.x provides several attributes which trigger actions, e.g.: ExceptionFilterAttribute (handling exceptions), AuthorizeAttribute (handling authorization). Both are defined in System.Web.Http.Filters. You could for instance define your own authorization attribute as follows: public class myAuthorizationAttribute : AuthorizeAttribute { protected override bool IsAuthorized(HttpActionContext actionContext) { // do … Read more
a_hash = {‘a’ => 30, ‘b’ => 14} b_hash = {‘a’ => 4, ‘b’ => 23, ‘c’ => 7} a_hash.merge(b_hash){ |k, a_value, b_value| a_value + b_value } => {“a”=>34, “b”=>37, “c”=>7} b_hash.merge(a_hash){ |k, b_value, a_value| a_value + b_value } => {“a”=>34, “b”=>37, “c”=>7}
You can do the following: #forms.py class ProductForm(ModelForm): class Meta: model = Product exclude = (‘updated’, ‘created’) def __init__(self, *args, **kwargs): super(ProductForm, self).__init__(*args, **kwargs) self.fields[‘description’].widget = TextInput(attrs={ ‘id’: ‘myCustomId’, ‘class’: ‘myCustomClass’, ‘name’: ‘myCustomName’, ‘placeholder’: ‘myCustomPlaceholder’})
[Browsable(false)] will hide a property from a DataGridView. A visual designer typically displays in the Properties window those members that either have no browsable attribute or are marked with the BrowsableAttribute constructor’s browsable parameter set to true. These members can be modified at design time. Members marked with the BrowsableAttribute constructor’s browsable parameter set to … Read more