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| Related Syntax | Related Concepts | ||||||||
| constant | #external-exception | ||||||||
Purpose
#external-exception is a built-in catch name that you can use to catch errors generated by OmniMark's interaction with the outside world. OmniMark will generate a throw to #external-exception when it encounters a problem dealing with the file system, for instance. Many OmniMark external function libraries will also throw to #external-exception when they encounter an error.
If a throw to #external-exception is not caught, OmniMark will generate a throw to #program-error.
#external-exception has three parameters:
identity, a stream that contains an identifying error code
message, a stream that contains a description of the error
location, a stream that contains the location of the error in the OmniMark source code.
When you create a catch for #external-exception, it is only necessary to specify the parameters you will be using in the catch block.
process local stream my-stream do open my-stream as file "/just/not/there" catch #external-exception output "Something went wrong. Don't know what it was.%n" done
The following code uses all the parameters of #external-exception.
process
local stream my-stream
open my-stream as file "/just/not/there"
catch #external-exception
identity error-code
message error-message
location error-location
output "I know what went wrong:%n"
|| "The error code is: " || error-code || "%n"
|| "The error message is: " || error-message || "%n"
|| "The error location is: " || error-location || "%n"
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Related Syntax #program-error always throw rethrow catch |
Related Concepts Catch and throw |
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