Generic class that can hold and accumulate data to be passed between Components.
The purpose of this class is to provide a flexible data structure that works a bit like a dict or blank Python class, but prevents the user from accessing members that have not been defined a priori (more like a C struct), and also keeps metadata information such as a description, defaults, and units for each item in the container.
Containers can transform the data into a
dictusing the ` Container.as_dict()` method. This allows them to be written to an output table for example, where each Field defines a column. The
dictconversion can be made recursively and even flattened so that a nested set of
Containerscan be translated into a set of columns in a flat table without naming conflicts (the name of the parent Field is pre-pended).
>>> class MyContainer(Container): >>> x = Field(100,"The X value") >>> energy = Field(-1, "Energy measurement", unit=u.TeV) >>> >>> cont = MyContainer() >>> print(cont.x) >>> # metadata will become header keywords in an output file: >>> cont.meta['KEY'] = value
Field`s inside `Containerscan contain instances of other
Containers, to allow for a hierarchy of containers, and can also contain a
Mapfor the case where one wants e.g. a set of sub-classes indexed by a value like the
telescope_id. Examples of this can be found in
Containerswork by shadowing all class variables (which must be instances of
Field) with instance variables of the same name the hold the value expected. If
Container.reset()is called, all instance variables are reset to their default values as defined in the class.