Re: [Gnumed-devel] demographics editor

[Hilmar Berger]

> Just today I had a similar issue crop up:
> 
> a) After starting GnuMed and before selecting a patient we
>    currently have no active patient.
> b) After starting GnuMed and before the user had any chance of
>    selecting a patient the initially raised plugin tries to
>    update itself.
> c) Since there is no patient it cannot update and may hang
>    unless precautions are taken.
> 
> Mainly, there are three solutions:
> 
> 1) in every plugin check for active patient and return if None there
>    - cumbersome,
>    - prone to forgetting,
>    - lot's of checking at every tab change for a rare corner case
Cumbersome ? Prone to forgetting ? Corner case ?
I call this appropriate handling of an error condigtion. This is a MUST.
We need to handle this case anyways (just in case something went wrong and
left us without a valid current patient).
This is independent of the question of loading patients at startup or not.
 
> 2) declaring a special widget that doesn't need a patient to
>    be the mandatory widget being raised initially
>    - just doesn't feel right technically (special values should
>      be avoided where possible, not created),
>    - doesn't sit well with the idea of loadable plugins
bad solution, as you have already said. 

> 3) take the design decision to *always* load a patient, even
>    before the user selected one
>    - sounds cleanest, technically
I'd call this an ugly hack.
>    - may need getting used to by some while not by others
>    - can still fail -- when there's not a single patient in
>      the database in the first place ...
>    - but this can be alleviated by a once per session
>      check that fails once per installation lifetime, then
>      creates a demo patient (uh, uh, special value, I know)
>      and thereafter always succeeds
Again, this is different from handling the case in which no patient was
specified. IMHO this is definitely no solution to the problem stated above.
 
Hilmar

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