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https://issues.apache.org/jira/browse/QPID-7943?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Keith Wall updated QPID-7943:
-----------------------------
Description:
The Broker's string resolution system
{{org.apache.qpid.server.util.Strings#expand()}}} uses an
{{OwnAttributeResolver}} to allow an object's attributes to be interpolated
into string values. This is provided by the {{this:<attribute name>}} syntax.
I have noticed that the value yielded by the expansion {{this:<attribute
name>}} within a context variable varies depending on where the context
variable is defined.
Imagine a context variable {{foo}} set with the value "{{${this:bar\}}}".
# If the context variable comes from the environment or from a managed context
default, the {{this:}} resolves at the target object. (i.e.
targetObject.getContextValue(String.class, "foo") yields a value equivalent to
targetObject.getAttribute("bar")).
# If the context variable is set on a ancestor object, the resolution takes
place at the ancestor ie. (i.e. targetObject.getContextValue(String.class,
"foo") yields a value equivalent to
targetObject.getParent()...getAttribute("bar"})
This behaviour surprises me. I don't think it leads to a current functional
issue. I think all our existing usages of {{this:}} are within managed context
defaults (fall into category 1).
was:
The Broker's string resolution system
{{org.apache.qpid.server.util.Strings#expand()}}} uses an
{{OwnAttributeResolver}} to allow an object's attributes to be interpolated
into string values. This is provided by the {{this:<attribute name>}} syntax.
I have noticed that the value yielded by the expansion {{this:<attribute
name>}} within a context variable varies depending on where the context
variable is defined.
Imagine a context variable foo set with the value "${this:bar}".
# If the context variable comes from the environment or from a managed context
default, the {{this:}} resolves at the target object. (i.e.
targetObject.getContextValue(String.class, "foo") yields a value equivalent to
targetObject.getAttribute("bar"}).
# If the context variable is set on a ancestor object, the resolution takes
place at the ancestor ie. (i.e. targetObject.getContextValue(String.class,
"foo") yields a value equivalent to
targetObject.getParent()...getAttribute("bar"})
This behaviour surprises me. I don't think it leads to a current functional
issue. I think all our existing usages of {{this:}} are within managed context
defaults (fall into category 1).
> [Java Broker] The result of the interpolation this: differs
> -----------------------------------------------------------
>
> Key: QPID-7943
> URL: https://issues.apache.org/jira/browse/QPID-7943
> Project: Qpid
> Issue Type: Bug
> Components: Java Broker
> Reporter: Keith Wall
> Priority: Minor
>
> The Broker's string resolution system
> {{org.apache.qpid.server.util.Strings#expand()}}} uses an
> {{OwnAttributeResolver}} to allow an object's attributes to be interpolated
> into string values. This is provided by the {{this:<attribute name>}} syntax.
> I have noticed that the value yielded by the expansion {{this:<attribute
> name>}} within a context variable varies depending on where the context
> variable is defined.
> Imagine a context variable {{foo}} set with the value "{{${this:bar\}}}".
> # If the context variable comes from the environment or from a managed
> context default, the {{this:}} resolves at the target object. (i.e.
> targetObject.getContextValue(String.class, "foo") yields a value equivalent
> to targetObject.getAttribute("bar")).
> # If the context variable is set on a ancestor object, the resolution takes
> place at the ancestor ie. (i.e. targetObject.getContextValue(String.class,
> "foo") yields a value equivalent to
> targetObject.getParent()...getAttribute("bar"})
> This behaviour surprises me. I don't think it leads to a current functional
> issue. I think all our existing usages of {{this:}} are within managed
> context defaults (fall into category 1).
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