Hi all,
On 08/21/2018 07:09 AM, Nyall Dawson wrote: > On Mon, 20 Aug 2018 at 23:17, DelazJ <del...@gmail.com> wrote: >> Good day devs, >> >> Today I was looking for an algorithm to create parallel lines in another >> layer and a search provides me with many candidates. I found >> >> - "translate": creates one parallel feature moved at a specified x/y/z/m >> offset distance >> - "array of offset features": same thing than translate but generating the >> parallel of the parallels up to the specified number of copies >> - "offset lines": applies an offset to the features (from what I see, it's >> an homothetic operation), generating one feature that is not a copy of the >> previous (not the same length, if multiline eg) >> - "create parallel lines": same as the offset lines tool but generating >> multiple offsets. >> >> I have some concerns/questions: >> >> -"translate" vs "array of offset features": why not just add the "number of >> features to create" parameter to the translate algorithm instead of having >> created a new one? >> - "offset lines" vs "create parallel lines": same question as above, in >> favor of the offset lines algorithm > My personal preference is to keep individual algorithms as simple as > possible, and have additional algorithms covering similar use cases. I > prefer this over the GRASS/SAGA algorithm approach of having one > algorithm with a multitude of parameters which interact in different > ways. In this case the algorithms have been separated into "vector > creation" algorithms (array of offset features, create parallel lines) > vs "geometry modification" algorithms (translate, offset lines). Fully agreed. The original grass plugin had this approach, and it worked very well IMHO in most cases. There are a few algs who cannot be easily made atomic without creating a messy set of very similar commands, but that's the exception rather than the rule. > >> with less algs, there will be less translation to do and I hope less >> confusion around this concept. > ...but I'm a strong -1 to squashing these operations into the same algorithm. again, fully agreed All the best. -- Paolo Cavallini - www.faunalia.eu QGIS & PostGIS courses: http://www.faunalia.eu/training.html https://www.google.com/trends/explore?date=all&geo=IT&q=qgis,arcgis _______________________________________________ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer