Built-in Functions
The Python interpreter has a number of built-in functions that are always available. They are listed here in alphabetical order:
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__import__(name[,globals[,locals[,fromlist]]]) This function is invoked by the
importstatement. It exists so that you can replace it with another function that has a compatible interface, in order to change the semantics of theimportstatement. For examples of why and how you’d do this, see the standard library modulesihooksandrexec. See also the built-in moduleimpthat defines some useful operations from which you can build your own__import__()function.For example, the statement
importspamresults in the call__import_ _('spam',globals(),locals(),[]); the statementfromspam.hamimporteggsresults in__import__('spam.ham',globals(),locals(),['eggs']). Even thoughlocals()and['eggs']are passed in as arguments, the__import__()function doesn’t set the local variable namedeggs; this is done by subsequent code that’s generated for the import statement. (In fact, the standard implementation doesn’t use itslocalsargument at all, and uses itsglobalsonly to determine the package context of theimportstatement.)When the name variable is of the form
package.module, normally, the top-level package (the name up to the first dot) is returned, not the module named byname. However, when a nonemptyfromlistargument is given, the module named bynameis returned. This is done for compatibility with the bytecode generated ...