reporting errors and warnings
It appears that when writing my own functions, I have two ways of creating
error or warning messages. I can use assert to make an error by writing:
dummy_variable = assert(condition, "Error message text"),
which sort of works. It's annoying that I need the dummy variable. And
it's also clutter that the condition gets displayed to the user. But for
warning messages, it appears that the advice is to use echo() and make the
text yellow. This seems ineffective because the statistics at the end of a
render always scroll off any text actually produced by the code, so I'm
reliant on that report at the top that tells me I had warnings so I know to
go look for them.
It would be nice if there was a way to make real error and warning messages,
e.g. as a flag to the echo() command, or as a new command that could
generate errors and warnings. Is there any plan to add this feature?
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On 16.03.19 16:13, adrianv wrote:
It's annoying that I need the dummy variable.
Why would you need that?
module fail() {
assert(false, "meh");
cube();
}
fail();
gives me a very nice
ERROR: Assertion 'false': "meh" failed in file tp, line 2
TRACE: called by 'assert', in file tp, line 2.
TRACE: called by 'fail', in file tp, line 6.
ciao,
Torsten.
It isn't ideal but we may get a warning count with something like:
xpto = condition ? echo( xpto, "your warning message") 0: 0
where xpto isn't used anywhere.
A sábado, 16/03/2019, 15:14, adrianv avm4@cornell.edu escreveu:
It appears that when writing my own functions, I have two ways of creating
error or warning messages. I can use assert to make an error by writing:
dummy_variable = assert(condition, "Error message text"),
which sort of works. It's annoying that I need the dummy variable. And
it's also clutter that the condition gets displayed to the user. But for
warning messages, it appears that the advice is to use echo() and make the
text yellow. This seems ineffective because the statistics at the end of a
render always scroll off any text actually produced by the code, so I'm
reliant on that report at the top that tells me I had warnings so I know to
go look for them.
It would be nice if there was a way to make real error and warning
messages,
e.g. as a flag to the echo() command, or as a new command that could
generate errors and warnings. Is there any plan to add this feature?
--
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tp3 wrote
On 16.03.19 16:13, adrianv wrote:
It's annoying that I need the dummy variable.
Why would you need that?
module fail() {
assert(false, "meh");
cube();
}
fail();
gives me a very nice
ERROR: Assertion 'false': "meh" failed in file tp, line 2
TRACE: called by 'assert', in file tp, line 2.
TRACE: called by 'fail', in file tp, line 6.
You don't get the message because you wrote a module instead of a function.
If I write a function:
function fail() = let(
assert(true, "It failed"))
0;
a=fail();
then I get
Loaded design '/home/adrian/scad/a.scad'.
Compiling design (CSG Tree generation)...
WARNING: Assignment without variable name undef, in file a.scad, line 1
Compiling design (CSG Products generation)...
Geometries in cache: 1
Geometry cache size in bytes: 1360
CGAL Polyhedrons in cache: 0
CGAL cache size in bytes: 0
Compiling design (CSG Products normalization)...
Normalized CSG tree has 0 elements
Compile and preview finished.
Total rendering time: 0 hours, 0 minutes, 0 seconds
The warning appears even when the assert succeeds---I just always get that
warning. So I need a dummy variable on every assert call. I need them on
echo calls within function as well.
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function fail() = let(
assert(true, "It failed"))
0;
a=fail();
WARNING: Assignment without variable name undef, in file a.scad, line 1
Yes, you get a warning because that code is assigning a
positional variable in let which is useless as there is
no way to access it afterwards.
I would use the function assert() like that:
function f(i) = let(x = assert(i > 1, "It failed") i) x * x;
echo(f1 = f(3));
echo(f2 = f(-3));
ciao,
Torsten.
tp3 wrote
Yes, you get a warning because that code is assigning a
positional variable in let which is useless as there is
no way to access it afterwards.
I would use the function assert() like that:
function f(i) = let(x = assert(i > 1, "It failed") i) x * x;
echo(f1 = f(3));
echo(f2 = f(-3));
I understand the behavior. But it's still annoying.
I'm not sure I understand your suggestion. It looks like you're suggesting
entangling the assert statement up with a nearby assignment. I think from a
readability and maintainability perspective, this is worse than using dummy
variables.
Code example:
function roundcorners(path, curve, type, all=undef, closed=true) =
let(
default_curvature = 1, // default curvature for "smooth" curves
dummy1=assert(curve=="smooth" || curve=="circle", "Unknown curve type in
roundcorners"),
typeok = type == "cut" || (curve=="circle" && type=="radius") ||
(curve=="smooth" && type=="joint"),
dummy2=assert(typeok, curve=="circle" ? "In roundcorners 'circle' curve
requires 'type' of 'radius' or 'cut'":
"In roundcorners 'smooth' curve
requires 'type' of 'joint' or 'cut'"),
<many more lines of code follow>
Having to use the dummy variables is a nuisance but if I had to take my pick
I'd prefer a real warning/error generating command over a workaround for
this, which seems like it might be syntactically complex. The best idea I
had for a workaround would be an official reusable dummy variable that
doesn't produce the "ignoring duplicate variable" warning, because the main
complication here is having to make sure all the dummy variables have unique
names.
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You don't need a dummy variable because assert can prefix an expression.
E.g.
let (nb = norm(binormal), x = assert(nb > 0.00001, "first three
points are colinear") nb))
On Sat, 16 Mar 2019 at 16:24, adrianv avm4@cornell.edu wrote:
tp3 wrote
Yes, you get a warning because that code is assigning a
positional variable in let which is useless as there is
no way to access it afterwards.
I would use the function assert() like that:
function f(i) = let(x = assert(i > 1, "It failed") i) x * x;
echo(f1 = f(3));
echo(f2 = f(-3));
I understand the behavior. But it's still annoying.
I'm not sure I understand your suggestion. It looks like you're suggesting
entangling the assert statement up with a nearby assignment. I think from
a
readability and maintainability perspective, this is worse than using dummy
variables.
Code example:
function roundcorners(path, curve, type, all=undef, closed=true) =
let(
default_curvature = 1, // default curvature for "smooth" curves
dummy1=assert(curve=="smooth" || curve=="circle", "Unknown curve type
in
roundcorners"),
typeok = type == "cut" || (curve=="circle" && type=="radius") ||
(curve=="smooth" && type=="joint"),
dummy2=assert(typeok, curve=="circle" ? "In roundcorners 'circle' curve
requires 'type' of 'radius' or 'cut'":
"In roundcorners 'smooth' curve
requires 'type' of 'joint' or 'cut'"),
<many more lines of code follow>
Having to use the dummy variables is a nuisance but if I had to take my
pick
I'd prefer a real warning/error generating command over a workaround for
this, which seems like it might be syntactically complex. The best idea I
had for a workaround would be an official reusable dummy variable that
doesn't produce the "ignoring duplicate variable" warning, because the main
complication here is having to make sure all the dummy variables have
unique
names.
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Yes, like nophead wrote, you should not need that.
Here's a more detailed example:
function f(a, b) =
assert(a < 0, "wrong a") // assert input
assert(b > 0, "wrong b") // assert input
let (c = a + b) // derive a new value from input
assert(c != 0, "wrong c") // assert derived value
a * b; // calculate
echo(f(-3, 5)); // ECHO: -15
//echo(f(3, 6)); // ERROR: Assertion '(a < 0)': "wrong a" failed in file tp, line 3
//echo(f(-4, -3)); // ERROR: Assertion '(b > 0)': "wrong b" failed in file tp, line 4
//echo(f(-1, 1)); // ERROR: Assertion '(c != 0)': "wrong c" failed in file tp, line 6
ciao,
Torsten.
tp3 wrote
Yes, like nophead wrote, you should not need that.
Here's a more detailed example:
function f(a, b) =
assert(a < 0, "wrong a") // assert input
assert(b > 0, "wrong b") // assert input
let (c = a + b) // derive a new value from input
assert(c != 0, "wrong c") // assert derived value
a * b; // calculate
This is a great solution to the problem. I don't like nophead's solution
because it mingles the computation into the assert in a way that's hard to
read, but this approach is clear. It didn't occur to me that assert could
take children. (This isn't mentioned in the manual at all.) I do wish
that let would allow a dangling comma on the last expression, which would
make it easier to insert and delete assignments.
But regarding the other issue, I still think it would be nice if there was a
way to generate warning and error messages from my code, without funny
business. It would be more clear to a user to see
ERROR: Value 'a' must be larger than zero in file tp, line 3
than
ERROR: Assertion '(a>0)': "Value 'a' must be larger than zero" failed in
file tp, line 3.
And of course there's no mechanism at all to generate a warning.
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Perhaps assert should be changed to a warning and if you want it to stop
like an error then you select stop on first warning.
On Sat, 16 Mar 2019 at 17:59, adrianv avm4@cornell.edu wrote:
tp3 wrote
Yes, like nophead wrote, you should not need that.
Here's a more detailed example:
function f(a, b) =
assert(a < 0, "wrong a") // assert input
assert(b > 0, "wrong b") // assert input
let (c = a + b) // derive a new value from input
assert(c != 0, "wrong c") // assert derived value
a * b; // calculate
This is a great solution to the problem. I don't like nophead's solution
because it mingles the computation into the assert in a way that's hard to
read, but this approach is clear. It didn't occur to me that assert could
take children. (This isn't mentioned in the manual at all.) I do wish
that let would allow a dangling comma on the last expression, which would
make it easier to insert and delete assignments.
But regarding the other issue, I still think it would be nice if there was
a
way to generate warning and error messages from my code, without funny
business. It would be more clear to a user to see
ERROR: Value 'a' must be larger than zero in file tp, line 3
than
ERROR: Assertion '(a>0)': "Value 'a' must be larger than zero" failed in
file tp, line 3.
And of course there's no mechanism at all to generate a warning.
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