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Capsule Types

The CtyCapsule type is a special type in pyvider.cty that allows you to encapsulate and protect foreign data types within the cty system. This is useful when you need to work with data that cannot be represented by the standard cty types, such as file handles, database connections, or other external resources.

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The CtyCapsule Type

To create a CtyCapsule type, you must provide a name for the type:

from pyvider.cty import CtyCapsule

file_handle_type = CtyCapsule("FileHandle")

This creates a new CtyCapsule type that can be used to encapsulate file handle objects.

Encapsulating and Accessing Data

You can encapsulate a foreign data type in a CtyCapsule value using the validate method:

# Create a dummy file handle object
class FileHandle:
    def __init__(self, path):
        self.path = path

file_handle = FileHandle("/path/to/file")

# Encapsulate the file handle in a CtyCapsule value
cty_file_handle = file_handle_type.validate(file_handle)

You can then access the encapsulated object using the raw_value property:

encapsulated_handle = cty_file_handle.raw_value
assert encapsulated_handle.path == "/path/to/file"

Type Safety

CtyCapsule types are type-safe. This means that you can only encapsulate objects of the correct type in a CtyCapsule value.

# This will raise a ValidationError
try:
    file_handle_type.validate("not a file handle")
except Exception as e:
    print(f"Validation failed: {e}")

This type safety ensures that you can't accidentally mix up different types of encapsulated data.

See Also