[cad-linux-dev] Re: Drawing entity
- From: Eric Wilhelm <ewilhelm@xxxxxxxxxxxxx>
- To: CAD linux development <cad-linux-dev@xxxxxxxxxxxxx>
- Date: Sat, 21 Aug 2004 10:48:17 -0500
# The following was supposedly scribed by
# Bruno Postle
# on Saturday 21 August 2004 10:16 am:
>The application knows to use the YAML parser from the file
>extension. =A0To access the centre-point, all it needs to do is
>look-up the ./my-circle.yml#version and ./my-circle.yml#type
>attributes and see if it has the code to handle a "foo" or "bar"
>formatted "circle" - Otherwise it skips the file with a warning.
>
>So the "version" and "type" attributes combined have basically the
>same function as an XML DOCTYPE declaration.
ok, but why "./my-circle.yml#version and ./my-circle.yml#type" ?
(btw, ./${circle}.yml#type eq 'circle', so let's call it #format)
I think it is a better plan in the long run to resign each directory to one=
=20
format and version.
./#version and ./#format
This gives one place to look for the version and format of the drawing. Af=
ter=20
all, you don't have mixed versions of entities in one dxf.
What if the directory structure changes? Yes, rhizopod is flat, but sturge=
on=20
may not be so flat.
In fact, I think rhizopod may actually need to be somehow broken into the=20
following parts:=20
geometry/
layers/
object_styles/
linetypes/
text_styles/
mark_styles/
So, for ($format eq 'rhizopod'), you should be able to count on finding one=
=20
directory structure for any value of $version. But, for ($version =3D=3D 0=
=2E01),=20
the keys inside the entities may possibly have different names/shapes than=
=20
for ($version =3D=3D 0.05). This implies a format layer and version layer =
in=20
your code/classes.
=46or starters, I'm just going to write-off mixed formats within a director=
y=20
completely. I don't see it as even feasible that rhizopod and sturgeon wou=
ld=20
have identical structures and filename conventions.
So, if $format is global to the directory, that leaves only the question as=
to=20
whether $version is an entity-level variable.
Doesn't it sound easier to switch code classes at drawing-open rather than=
=20
entity-open? Also, I know it is possible to write code to switch at=20
entity-open, but is it worth it? What real-world situation justifies it?
=2D-Eric
=2D-=20
"Unthinking respect for authority is the greatest enemy of truth."
--Albert Einstein
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