4e5ac45ec5
Add one option, which is the motivating example, a way to control what happens when a map is indexed with a key that is not in the map. Rather than do something specific for that case, we provide a simple general option mechanism to avoid adding API if something else comes up. This general approach also makes it easy for html/template to track (and adapt, should that become important). New method: Option(option string...). The option strings are key=value pairs or just simple strings (no =). New option: missingkey: Control the behavior during execution if a map is indexed with a key that is not present in the map. "missingkey=default" or "missingkey=invalid" The default behavior: Do nothing and continue execution. If printed, the result of the index operation is the string "<no value>". "missingkey=zero" The operation returns the zero value for the map type's element. "missingkey=error" Execution stops immediately with an error. Fixes #6288. Change-Id: Id811e2b99dc05aff324d517faac113ef3c25293a Reviewed-on: https://go-review.googlesource.com/8462 Reviewed-by: Robert Griesemer <gri@golang.org> |
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The Go Programming Language
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