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https://issues.apache.org/jira/browse/THRIFT-5749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17798152#comment-17798152
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Jens Geyer edited comment on THRIFT-5749 at 12/18/23 11:49 AM:
---------------------------------------------------------------
Enabling RTTI comes with small, but necessary changes to the generated code.
*With RTTI enabled:*
- the interfaces derive from {{IBaseWithTypeInfo}} which in turn derives from
{{IBase}}.
- binary translates to {{TThriftBytes}} instead of {{System.TBytes}} to
prevent against {{E2134 "TBytes has no typinfo"}}.
{{TThriftBytes}} is assignment compatible to {{TBytes}} but it may require
other code changes, e.g. when using {{Length()}}.
Implementing/querying {{IBaseWithTypeInfo}} is not necessary/foreseen, its
only purpose is to add typeinfo.
*Compatibilty note:*
There may cases where activating RTTI leads to uncompileable code, presenting
{{E2134 "TMyEnum has no typinfo"}} where {{TMyEnum}} is an "irregular" enum
like {{TNumberz}} from the test suite. This is a known limitation of the Delphi
RTTI system [1] and *NOT* a bug in Thrift. At this time, you simply cannot use
RTTI with such enums, unless Embarcadero finally does that stuff right.
[1]
https://stackoverflow.com/questions/1420562/why-do-i-get-type-has-no-typeinfo-error-with-an-enum-type
was (Author: jensg):
Enabling RTTI comes with small, but necessary changes to the generated code.
*With RTTI enabled:*
- the interfaces derive from {{IBaseWithTypeInfo}} which in turn derives from
{{{}IBase{}}}.
- binary translates to {{TThriftBytes}} instead of {{System.TBytes}} to
prevent against {{{}E2134 "TBytes has no typinfo"{}}}.
{{TThriftBytes}} is assignment compatible to {{TBytes}} but it may require
other code changes, e.g. when using {{{}Length(){}}}.
Implementing/querying {{IBaseWithTypeInfo}} is not necessary/foreseen, its only
purpose is to add typeinfo.
*Compatibilty note:*
There may cases where activating RTTI leads to uncompileable code, presenting
{{E2134 "TMyEnum has no typinfo"}} where {{TMyEnum}} is an "irregular" enum
like {{TNumberz}} from the test suite. This is a [well-known limitation of the
Delphi RTTI
system|[http://example.com|https://stackoverflow.com/questions/1420562/why-do-i-get-type-has-no-typeinfo-error-with-an-enum-type]]
and *NOT* a bug in Thrift. At this time, you simply cannot use RTTI with such
enums, unless Embarcadero finally does that stuff right.
> Option to enable RTTI info
> --------------------------
>
> Key: THRIFT-5749
> URL: https://issues.apache.org/jira/browse/THRIFT-5749
> Project: Thrift
> Issue Type: Improvement
> Components: Delphi - Compiler
> Reporter: Jens Geyer
> Assignee: Jens Geyer
> Priority: Major
> Fix For: 0.20.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> In some cases it would be helpful to have RTTI info available for generated
> API interfaces.
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