[PATCH setup] Add view mode "Unneeded"

[Jon Turney]

On 15/08/2022 14:04, Christian Franke wrote:
> Jon Turney wrote:
>> On 02/08/2022 13:17, Christian Franke wrote:
>>> In long standing cygwin installations, many no longer needed 
>>> automatically installed packages (e.g. libicuNN) accumulate. This 
>>> patch adds a new view which is possibly helpful to cleanup packages 
>>> manually.
>>>
>>> Some possible later enhancements:
>>> - automatically refresh this view (a few seconds) after the user 
>>> changed a package status as this may add or remove entries.
>>> - add a keyboard shortcut (^U) to the list view for "Uninstall this 
>>> package and then select next package"
>>>
>>
>> Thanks.  This looks good.
>>
>> I think perhaps a better approach would be a view showing all packages 
>> which aren't user_picked, or a dependency of a user_picked package.
> 
> This would drop the ability to easily clean up user_picked packages 
> without later conflicts. The attached new patch splits this into two 
> views "Removable" (not "Uninstallable" due to possible ambiguity with 
> "cannot be installed") and "Unneeded" (or "Stale" ?).
>  
>>
>> (If I've read the code correctly your implementation has the weakness 
>> that if e.g. appA -> libbB -> libC, which is then changed to appA -> 
>> libD -> libE, it will only show libC as unneeded, then libB on the 
>> next run?)
> 
> I'm not sure for this case. It may be correct again after the view is 
> refreshed during the same run. In general, this ad-hoc algorithm does 
> not handle all corner cases. It should be sufficient if installation 
> cleanup is done in a separate run.
> 

Thanks.  I applied this.

I'm not sure these are the perfect filters, but they are a lot better 
than the nothing we have at the moment :)

Some time ago, I thought about replacing the "view"s list with a 
drop-down menu which would let you choose how to filter and show the 
package list, but I don't think I got around to writing anything...

e.g

---
[x] Installed
[✓] Changed
[ ] Picked
[ ] Needed
---
[✓] Category
[ ] List
---

(I think the filter menu items would need to be tri-stateable so they 
can represent "true", "false" and "don't care", so this might be complex 
to implement...)

Later: actually it looks like I started writing some of this [1], but 
didn't get very far...

[1] 
https://github.com/jon-turney/cygwin-setup/tree/split-view-filter-and-style

>>> +// Scan installed or desired packages and collect the names of packages
>>> +// which provide the dependencies of other packages or are member of
>>> +// category "Base".
>>> +static void FindNeededPackages (const packagedb & db, 
>>> std::set<std::string> & needed)
>>> +{
>>> +  std::map<std::string, std::string> providedBy;
>>> +  for (const auto & p : db.packages)
>>> +    {
>>> +      const packagemeta & pkg = *p.second;
>>> +      if (!pkg.isBinary ())
>>> +        continue;
>>> +      if (!(pkg.desired && (pkg.installed || pkg.picked ())))
>>> +        continue;
>>
>> This seems redundant.  Why can't this be just !pkg.desired?
> 
> Yes, fixed. I originally wanted to handle the "install source package 
> without the binary" case here. During development of "Ctrl+I/R/U" patch, 
> I learned that this could not happen.
> 
> 
>> This should also update the tooltip for the view dropdown 
>> (IDS_VIEWBUTTON_TOOLTIP) to describe the new view.
>>
> 
> Done.