[Kbabel] RFC: Proposal for enabling/disabling actions

[Marco Wegner]

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Hi,

in the last hour I've been trying to think of a system which should make the
enabling and disabling of actions in Catalog Manager much easier.

Until recently the current system with states defined in the file
catalogmanagerui.rc has been quite sufficient. But already the toggeling of
the appropriate CVS actions has shown the limits of this system. Right now I
am working on features which apply only to directories. Just another state
which is not covered by the current implementation. Therefore I thought a
different approach could be helpful. So here are my thoughts:

Instead of defining different states in the *ui.rc file we could simply create
a bit matrix:

Bit 0: current item has PO file
Bit 1: current item has POT file
Bit 2: current item is marked
Bit 3: current item is dir
Bit 4: a valid CVS PO repository exists
Bit 5: a valid CVS POT repository exists

If one of these things is necessary to enable an action then the appropriate
bit is set. Examples:

- - rough translation: 0 (can be applied to any item)
- - spell check: 1 (needs PO file)
- - mail marked files: 5 (needs PO file and a mark)
- - cvs update: 17 (needs PO file and a valid PO repository)
- - cvs commit marked templates: 38 (needs POT file, a mark and a valid POT
repository)

I think the idea should be clear by now :-) These values can be QMap'ped
against the names of the actions. I call this value 'actionValue' for the
better understanding of issues coming later on.

To decide which actions are enabled/disabled for the current item we just
create the bit pattern for the current item like this (item is a
CatManListItem*):

uint itemValue = 1*item->hasPo( ) + 2*item->hasPot( ) + 4*item->isMarked( ) +
  8*item->isDir( ) + 16*isValidPORepository + 32*isValidPOTRepository;

Traverse the list of actions and set those enabled for which the associated
'actionValue' combined by bit-wise AND with the above created 'itemValue' has
the 'actionValue' as a result. If this is not the case set the action
disabled. Examples:

The current item has PO file, POT file, is not marked and has valid PO and POT
repositories -> itemValue results in 51

- - rough translation: (51 AND 0) == 0 -> enable
- - spell check: (51 AND 1) == 1 -> enable
- - mail marked files: (51 AND 5) != 5 -> disable
- - cvs update: (51 AND 17) == 17 -> enable
- - cvs commit marked templates: (51 AND 38) != 38 -> disable

I hope I made myself sufficiently clear. I'd like to hear your comments on
this. It is easy to implement and should not need much more (if any) code
than the current system. It also shouldn't be slower than using states but is
more flexible all the same.

BTW: This system can be applied to the the actions in the markings and tools
menu. But I'm sure a similar system can be created for the correct toggeling
of 'go to' actions.

Marco

- --
Marco Wegner <mail@marcowegner.de>, <dubbleu@web.de>
Contributing to KBabel http://i18n.kde.org/tools/kbabel
   and German KDE translation http://i18n.kde.org/teams/de
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