It certainly would be helpful if code that requires a recent snapshot
(something past the current release) could be flagged so that the user
saw an informative message if they attempted to run with an older compiler.

Unfortunately, it would be difficult to write a compiler that recognized
a feature newer than the compiler's release date, and emitted a
message.  But that would be nice! <grin>

On 1/22/2022 9:30 AM, Adrian Mariano wrote:

What error message do you see? I think it has always been valid syntax but
assert might be an undefined module or version an undefined function.

On Sat, 22 Jan 2022 at 14:36, jon jon@jonbondy.com wrote:

I'm not asking for the compiler to magically recognize code from
future versions.  I'm asking for a way to say "this code requires
version 2019.1 or newer" that actually works when the subsequent code
is not valid.  This actually seems like it ought to be pretty easy to
implement.  It's up to the author of the code to know what version is
needed and insert the requirement.

In answer to nophead:

dummy=assert(version()[0]>=2021);
a=2^3;

when run under 2019.5 gives the message:

ERROR: Parser error in file "/home/adrian/scad/test30.scad", line 2:
syntax error

because the '^' is not recognized.  This is not such an old version
that assert() wasn't supported.  If I change it to:

dummy=assert(version()[0]>=2021);
a=pow(2,3);

and run in 2019.5 then I get:

ERROR: Assertion '(version()[0] >= 2021)' failed in file test30.scad, line 1

Obviously the issue is that OpenSCAD parses the file before it runs
it, so it gets the parse error before it runs the assert.

On Sat, Jan 22, 2022 at 9:36 AM jon jon@jonbondy.com wrote:

I agree because recently I something I posted on Thingiverse failed on
someone and it confused them (their version didn't have function literals).

Maybe there could be an optional version comment that gets checked
before parsing (there's already precedent for interpreting comments
since the Customizer does it, albeit that's after parsing).

// version [2021.01 : ]

Cheers,
Curt

On 1/22/2022 6:30 AM, Adrian Mariano wrote:

Yes but any change needs to be in a new version, so how will that help
people with old versions?

On Sun, 23 Jan 2022 at 10:21, Curt McDowell maker@fishlet.com wrote:

They can't be helped, but presumably the majority of users are in the
future.

On 1/23/2022 3:13 AM, nop head wrote:

I think you may be able to bodge around it using the existence or not of any special variables that came into existence with a specific release e.g.

$preview came in with 2019.05
$vpf  came in with 2021.01

newer = is_undef($vpf);
assert (!newer, "Need newer Level of OpenSCAD”);

cheers
Bob.C

OpenSCAD has a version() function that returns the version.  The
problem is not figuring out if the version is OK.  The problem is that
if it's not, you get a syntax error before any assert() statements
run, so it doesn't do any good.

On Sun, Jan 23, 2022 at 9:38 AM Bob Carter caggius@gmail.com wrote:

On Sun, Jan 23, 2022 at 11:13:06AM +0000, nop head wrote:

You can recommend:

// This checks for openscad version 2022.2 or later
check_version (2022, 2);

If that errors out with a line number on older versions, people will
at least be pointed to the right line number about why the file
doesn't work.

I spent a day and a half debugging "module xyz not found" messages in
a python program. Turns out the program was not compatible with
python-2. Something I installed depended on python-2 so the python-2
install script decided: You installed me last, so I get to claim
/usr/bin/python.

An error message: "This program requires python-3" would've been nice
to point me in the right direction. Even an error message:

syntax error on the line 123:

122: // we need a reasonably recent python
123: python version needs to be at least 3.5
124:

would have been nice. Even if python-2 errors on that line.

Roger. 

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