[erlang-questions] clarify: why does Dialyzer have an implicit dependency on Mnesia?
Wed Dec 12 21:16:53 CET 2007
Eric Merritt wrote:
> Dialyzer seems to have an implicit dependency on Mnesia. Mnesia isn't
> specified as a dependency in dialyzer.app, nor does dialyzer ever
> actually call any of the Mnesia APIs. However, dialyzer attempts to
> get information about mnesia in dialyzer_plt. It makes use of a list
> of default libraries provided by the dialyzer header. Why is this? If
> there actually is a dependency shouldn't dialyzer have mnesia listed
> as a dependency in its .app file? If its not a dependency why try to
> retrieve information about it with the code module?
I am not 100% sure what you are referring to, but most probably you are
talking about the fact that by default Dialyzer builds (or these days
comes with) an initial PLT (Persistent Lookup Table) of the following
This is done so that there is cached type information about functions
that an application might be using -- thereby avoiding having to include
modules of these applications in each analysis and repeatedly analyzing
these modules. However, dialyzer needs to check that the cached type
information is still valid (i.e. has not changed since the time when the
PLT was built) and thus checks that the .beam files have not changed by
comparing their checksums with the current one. Thus, it needs to be
able to locate these .beam files.
In principle, no application is needed in PLT or more than the above
three could be added, so if it bothers you feel free to take mnesia out
of the set of applications in the PLT (these are specified in dialyzer's
Makefile) and rebuild the PLT.
Hope this answers your question.
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