[Qgis-developer] Saving expressions

[Andreas Neumann]

 Hi Paolo,

 What do you expect from the loading? Automatic application to the field 
 calculator (sounds scary to me), or just the ability to choose from past 
 expressions?

 If the latter, then maybe a central expression storage (per user) would 
 make more sense than a per layer expression store. Because you may want 
 to reuse the same expression on another similar layer, even in different 
 projects.

 To me the expressions do not have a natural 1:1 match to a layer like 
 the .prj or the .qml file has.

 But I can see value in a central storage of expressions used in the 
 past, regardless of layer and QGIS project. But it would just be used as 
 a way to load and save expressions as templates to start from and not an 
 automatic application to some calculation or the label engines. These 
 settings should be better stored in the project itself rather than in a 
 separate file.

 Do we agree on that or did I misunderstand you?

 Andreas

 On Fri, 19 Oct 2012 07:58:57 +0200, Paolo Cavallini wrote:
> Il 19/10/2012 07:51, Andreas Neumann ha scritto:
>> For me personally, copy/paste works fine. No need for load and save.
>>
>> I do not fully understand the use case for autoloading (association
>> with a layer). Can you explain why this is desirable? Do you really
>> always want the same expression in all projects for one particular 
>> layer?
> I think users will fin useful to have their expression per layer, so
> they can refresh a field with the same calculation, without the need 
> to
> rememberwhich formula they used (very stupi example: refreshing the 
> AREA
> field). In this way, a DBF can be used almost like a spreadsheet.
> For advanced users it is probably useless, for newbies it can save a
> loto of time, effort and frustration remembering which expression 
> they
> used, what is the exact syntax, where (if) they copied the expression
> somewhere, etc.
>
> All the best.

-- 
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 Andreas Neumann
 Böschacherstrasse 10A
 8624 Grüt (Gossau ZH)
 Switzerland