Re: [MirageOS-devel] command line arguments for unikernels

[Daniel BÃnzli <daniel.buenzli@xxxxxxxxxxxx>]

Le jeudi, 4 dÃcembre 2014 Ã 16:02, Thomas Gazagnaire a Ãcrit :
> I am not very fond of the default references, not sure why you want someone 
> to change them globally.

Same reaction, changing defaults by side effects is a recipe for crazy 
debugging sessions. Always assume users will abuse what you put in their hands; 
so minimize the exposition of (unecessary) side-effects.

Other things:

1) You need to tell us something about some notion of identity for the 
parameters. How is it defined
is it the name ? What happens if I declare two parameters with the same name 
[1] ?  

2) In the manpage I would list the parameters under a different section (e.g. 
one called UNIKERNEL PARAMETERS).

3) I would prefix or suffix the command line option name with a constant, this 
ensures that unikernel developers will never clash with options of the mirage 
tool. So for a parameters named "address" the option names should be  
`--address-param` or `--param-address`  

4) Is the no [def] with [dyn] unspecified option runtime error a feature ? If 
not it's easy to ensure statically you always have a value to use. Are you 
using cmdliner's required optional arguments for that (it seems a legitimate 
use for once, as it would be difficult to make positional arguments in a 
compositional manner) ?  

Best,

Daniel

P.S. Rather than configuration Param I would use configuration Key which is 
shorter and a full word, but naming is subjective.


[1]  That's:

https://github.com/samoht/assemblage/blob/757b36c6b880b3a86b6177277e2a66555bfb7af2/lib/assemblage.mli#L1091-L1096

what assemblage says on the topic. Basically we have uid internally so we don't 
discriminate on the name. However that warning in the documentation is over 
pessimistic. In fact if I get two configuration keys with the same name I emit 
a warning and generate an alternate name for the option on the command line 
(e.g. --dupname~1-key). See here:

https://github.com/samoht/assemblage/blob/757b36c6b880b3a86b6177277e2a66555bfb7af2/lib-driver/assemblage_driver.ml#L42-L53







 but if you have two configuration with the same name,  I think that in 
assemblage this is not a real problem (unless you load more than one project)




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