Sketch.ExpressionEngine: Failed to parse expression.

[adrianinsaval]

what about the behavior when renaming a constrain/setting to reference? separate issue or the same? I think there's an existing issue for the reference constrain but I can't find it... perhaps when renaming/setting to reference the contrain the expressions can be evaluated and raise an error/warning?

[dprojects]

what about the behavior when renaming a constrain/setting to reference? separate issue or the same? I think there's an existing issue for the reference constrain but I can't find it... perhaps when renaming/setting to reference the contrain the expressions can be evaluated and raise an error/warning?

I think it is not matter if you edit or create new one. However, I think there should be more tests done by someone who know FreeCAD code to make sure if the bug is not related to something bigger. If this is not like it depends on something else, because this is strange behavior the single word is sometimes working and sometimes not. This is also not related to structure, because it exists without Pad, or Array.

This is strange but looks like the open file part should be checked more deeply in relation of XML parsing.

EDIT: Also what is strange, the values are correctly calculated, so the expressions are calculated correctly, this only loses expressions, they are even removed from the XML file content during reopen. So, if you want to keep expressions for testing purposes, you have to save the file just after close. If you reopen the file you lost expressions from testing file.

[adrianinsaval]

I think it is not matter if you edit or create new one. However, I think there should be more tests done by someone who know FreeCAD code to make sure if the bug is not related to something bigger. If this is not like it depends on something else, because this is strange behavior the single word is sometimes working and sometimes not.

Like I said, I was not able to use a constrain with space in the name in an expression directly, only by renaming an existing constrain. And I am not able to make Bottom fail, with or without other invalid names around. Provide an example if you have it.
Eitherway, I was just asking if a separate issue should be created for the behavior when renaming. I did not say this was the only problem.

[dprojects]

Like I said, I was not able to use a constrain with space in the name in an expression directly, only by renaming an existing constrain. And I am not able to make Bottom fail, with or without other invalid names around. Provide an example if you have it.
Eitherway, I was just asking if a separate issue should be created for the behavior when renaming. I did not say this was the only problem.

So, this is strange. I can add any name, for new constraints and also with edit. It only not allow to add duplicated name.
What OS and FreeCAD version you have? Maybe this is related to version or OS? or python version library? XML parse or Qt?

[adrianinsaval]

So, this is strange. I can add any name, for new constraints and also with edit. It only not allow to add duplicated name.
What OS and FreeCAD version you have? Maybe this is related to version or OS? or python version library? XML parse or Qt?

I can name the constrains however I want new or editing and this survives save an reopen without issues, but I can't input a name with a space in a expression. Here my FreeCAD info:

Code: Select all

OS: Windows 10 (10.0)
Word size of FreeCAD: 64-bit
Version: 0.20.27809 (Git)
Build type: Release
Python 3.8.12, Qt 5.12.9, Coin 4.0.0, OCC 7.5.3
Locale: Spanish/Paraguay (es_PY)
Installed mods: 
  * ArchTextures
  * CurvedShapes 1.0.0
  * Curves 0.3.0
  * Defeaturing
  * fasteners 0.3.38
  * Glass
  * SelectorToolbar
  * Silk -831323728.0.0

[adrianinsaval]

Another similar problem with spaces in the name, make two constrains, give one a valid single word name, set the second to a expression with the first and hit ok, edit the second constrain again and give it a spaced name and hit ok, close the file, reopen the file and get failed to parse expression.
Even if the expression itself was valid it fails. Spaces (and maybe special characters? unit identifiers on their own too probably) in constraint names should be forbidden IMO.

(asked realthunder about this stuff since one of his PRs is supposed to address spaces in the name: https://forum.freecadweb.org/viewtopic. ... 05#p580505)

[dprojects]

I tested at:

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FreeCAD_weekly-builds-27936-Linux-Conda_glibc2.12-x86_64.AppImage

with the same result, so this might be related to something else, OS or Library version.
Open the attached file and write what left for you, for me left nothing, all expressions was removed.

[chrisb]

Even if the expression itself was valid it fails. Spaces (and maybe special characters? unit identifiers on their own too probably) in constraint names should be forbidden IMO.

I would have no problem in hardcoding these (copied from Expressions):

Bildschirmfoto 2022-03-16 um 23.10.02.png (71.98 KiB) Viewed 1209 times

But the names can also be used for documentation, especially with the new possibility of showing them in 3D view. In that case they may never occur in any expression and no problem would occur.
The names are given before any expression can reference them and thus it cannot be checked if it is necessary to have an expression-conformant name.

I hardly ever see the usage of documentation names in Sketcher constraints. It should be possible to find a decent replacement name for names which now use one of the forbidden characters. So I think it would indeed be helpful to restrict the names of constraint names.

[adrianinsaval]

I tested at:

Code: Select all

FreeCAD_weekly-builds-27936-Linux-Conda_glibc2.12-x86_64.AppImage

That is not the proper way of providing FreeCAD info as it ommits information that is often relevant (qt, occ and other libraries version, in this particular case I don't think they matter). Proper way is to go to Help->About FreeCAD->Copy to clipboard

with the same result, so this might be related to something else, OS or Library version.
Open the attached file and write what left for you, for me left nothing, all expressions was removed.

No expressions left inside the sketch, but notice the issue I mentioned above, even valid expressions using single word named constrains fail to parse if they are used to set the value for a constraint with a space in the name.
So if you use top (which is valid) in Botom size test 1 (which isn't) it will fail to parse, the same as if you use Bottom, width in top23_r.

[dprojects]

No expressions left inside the sketch, but notice the issue I mentioned above, even valid expressions using single word named constrains fail to parse if they are used to set the value for a constraint with a space in the name.
So if you use top (which is valid) in Botom size test 1 (which isn't) it will fail to parse, the same as if you use Bottom, width in top23_r.

Yes, you are right ! This is why sometimes single word is working and sometimes not. It depends if you use "not valid" name or not. I make little more research on that:

If you add only valid names they all survive reopen (no errors at console, after reopen):


Also I make test for 0.18.4 version natively installed at Ubuntu, and this is even more strange. If you add "not valid" name the reference will not be visible but after reopen they exists !