kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

Seppe,

I'm comfortable with discussing this change.  We are trying to remove
unnecessary board file stuff for improved VCS experience.  However, this
change is a board file format change and we are currently in feature
freeze so it will have to wait until after the v5 stable release.

Cheers,

Wayne

On 4/24/2018 5:35 AM, Seppe Stas wrote:
> I would like to remove the counters of the general section in the KiCAD
> PCBNew's file format. By counters I mean the
> links, no_connects, drawings, tracks, zones, modules and nets elements
> in the general section. E.g:
> 
> (general
>     *(links 280)*
>     *(no_connects 0)*
>     (area 29.899999 29.899999 225.100001 106.600001)
>     (thickness 1.6)
>     *(drawings 67)*
>     *(tracks 987)*
>     *(zones 0)*
> *    (modules 108)*
> *    (nets 81)*
>   )
> 
> When checking PCB designs into a SCM these counters make it virtually
> impossible to handle merges, since they pretty much always cause merge
> conflicts. Even if someone commits a small fix on the other side of the
> board another person is working on, this fix could (and typically does)
> cause one of the counters to change, resulting in a merge conflict. The
> only ways to fix the conflict is manually calculating the new values for
> the conflicting counters or re-doing the fix. Both methods are a pain
> for people not that familiar with the SCM (most people).
> 
> These counters are also redundant, potentially causing inconsistency
> because of potential bugs in PCBNew or by altering the PCB file manual
> (something I often end up doing due to limitations of PCBNew) or using
> third-party tools like my company's tooling
> <https://github.com/productize/kicad-parse-gen> (again, to cope with
> limitations in PCBNew).
> 
> By looking into the code I found that only the "nets" and "no_connects"
> counters are actually parsed by PCBNew, the others are ignored (see
> pcb_parser:cpp:~600). The netlist counter is only used to set an initial
> size for the `m_netCodes` map. When finding new netlists this map is
> resized, so it should work (inefficiently) without it. Setting a big
> enough value or resizing using grow algorithm
> <https://en.wikipedia.org/wiki/Dynamic_array> (a bit more memory
> intensive) or counting the nets in the file (more io intensive) would
> make it more performant.
> 
> The amount of unconnected nets can just be calculated by building the
> board's ratsnest (PCB_BASE_FRAME::Build_Board_Ratsnest) after parsing it.
> 
> I would like to commit a patch for this, but I would like to discuss how
> backwards compatibility could be handled first.
> 
> Greeting
> Seppe Stas
> 
> 
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