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persistence

Knowing the type of error is not enough

When a file I/O error occurs, your code displays a generic “File Error”
message. This is too generic. How do you know what actually happened?

It could be that the Yeah, or it could be
file can be opened but a permission error, or
Maybe the problem not written to? maybe your disk is full?
is that you can’t open
the file?

Who knows?

It turns out that the Python interpreter knows…and it will give up the details
if only you’d ask.

When an error occurs at runtime, Python raises an exception of the specific
type (such as IOError, ValueError, and so on). Additionally, Python
creates an exception object that is passed as an argument to your except
suite.

Let’s use IDLE to see how this works.

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