Web dialog fractions conversion

Garry K · 3 Jan 2014, 17:58

My model is set to millimeters 0.001 precision.

Using a web dialog I enter the following values and use text.to_l to convert

These are as expected

400 ends up as 400.000mm
300mm ends up as 300.000mm
16" ends up as 406.400mm
3 7/8 ends up as 3.875mm This one is suspicious

But then this happens

2 1/2" ends up as 2.500mm

Is this a bug or am I doing something wrong?

I suppose that I could check for '/' and then treat and if found multiply the result by
25.4 if metric. It appears that I will have to do some testing to see if there are any other conversion issues.

Garry K · 3 Jan 2014, 18:44

After further testing it appears that this is the only conversion that fails ( I'm currently only interested in mm and inches )

I have tested Version 7,8 and 2013 and all give the same results.
I have also tested Sketchup's input box and it also gives the same results.

def get_value( text )
tmp = text.to_l

if ( @@metric == true && text.index( '/' ) != nil )
val = ( ( tmp * 25.4 ).to_s + '"' ).to_l
else
val = tmp
end

puts val

return val
end

Dan Rathbun · 4 Jan 2014, 03:45

Have you read Thomas' "Dealing with Units in SketchUp" ?
http://www.thomthom.net/thoughts/2012/08/dealing-with-units-in-sketchup/

Always assume the user wishes to enter values in model units.

Dan Rathbun · 4 Jan 2014, 03:58

@garry k said:

But then this happens

2 1/2" ends up as 2.500mm

Is this a bug or am I doing something wrong?

It works for me if I make sure to escape the inch symbol, or use a single quoted string:

` n = '2 1/2"'.to_l
0.0984251968503937

n = "2 1/2"".to_l
0.0984251968503937`

You can test if a string contains a double quoted character thus:
if num =~ /\"/

Garry K · 4 Jan 2014, 06:23

I'm on a different wave length here.

If you have a Sketchup inputbox that has a length.
The model is in millimeters and use precision of 0.001 just because.

Now the user enters 2 1/2" into the input box ( they will never understand that you need to escape the double quote.

It comes out as 2.500mm

This is NOT as expected - regardless.

I know myself that I work mostly in millimeters but feel quite at home going back and forth. All the other built in conversions work just fine. Just not this one.

Furthermore - my experience in CAD goes back to DOS. I allow my users ( when I code in C++ ) to enter inches when in millimeters and visa versa. Additionally I allow users to enter mathematical expressions that I evaluate such as:

in milimetes
(905 - 20) / 5
which evaluates as 177mm

If 95% of logical data entry works - and 5% doesn't - users will naturally tend to see that as a bug.

But not to worry as I have a work around - but not for Sketchup inputbox as we don't get to see what the user entered.

jolran · 4 Jan 2014, 08:29

http://sketchucation.com/forums/viewtopic.php?t=36722

There are some conversion methods in there to take inspiration from..

Garry K · 4 Jan 2014, 15:48

Thanks Jolran - this is helpful. I can perhaps add math expression parsing at a later date!

Dan Rathbun · 4 Jan 2014, 21:08

@garry k said:

This is NOT as expected - regardless.

I know myself that I work mostly in millimeters but feel quite at home going back and forth. All the other built in conversions work just fine. Just not this one.

Yes I think it IS a bug.

Today I tested with a model set to decimal feet (0.001) and got this:
` '2 1/2"'.to_l
30.0

Sketchup::format_length('2 1/2"'.to_l)
2.500'`

So the inch symbol is ignored.

But in a model set to inches:
"2.54'".to_l %(#008000)[30.48]
So it seems the foot symbol works, IF the numeric is decimal.

But IF it is fractional (model set to inches):
"2 1/2'".to_l %(#008000)[24.0]

**So I agree. It is a bug issue with fractional expressions.

ADD: The error also occurs within the VCB (Measurements Box) !**