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6576 :: cstring to string?

[2020-07-23T05:49:38+02:00]

cdunn2001 (orginal) [2020-07-23T05:49:38+02:00] view original
I'm trying to update my code for the latest Nim, and I'm hitting a weird error:
```
228                 except Exception as exc:
229                     let name: string = exc.name

t_raptor_db.nim(229, 43) Error: type mismatch: got <cstring> but expected 'string'
```
I'm trying to compare with the name of the exception. Why am I unable to convert from "cstring" to "string"?

miran (orginal) [2020-07-23T06:03:29+02:00] view original

Why am I unable to convert from "cstring" to "string"?
Because you're not really converting. You're passing a cstring (right hand size of =) to something you declared as string (left hand side).

Try the following: let name = exc.name.string

cdunn2001 (orginal) [2020-07-23T06:22:48+02:00] view original
Same error. Here is what I had:
```
-                    if exc.name == expected:
+                    let name: string = exc.name.string
+                    if name.startsWith(expected):
```
See? When I was comparing cstring to string, it was working, but now I need to test only the start (because the name changed from AssertionError to AssertionDefect). So now I'm wondering how the comparison worked if I am unable to type-convert.

cdunn2001 (orginal) [2020-07-23T06:24:18+02:00] view original

Btw, I'm at the bleeding edge:


commit ec65bfae3ac20a6c3d13249bc1fc8413db2b3abb (HEAD -> devel, origin/devel, origin/HEAD)
Author: Miran <[email protected]>
Date:   Wed Jul 22 05:57:40 2020
    
    Change testing commands for some packages (#15041)

So I'd understand if it's just a bug. But it's surprising to me.

snej (orginal) [2020-07-23T20:24:22+02:00] view original

According to the manual, the correct conversion from cstring to string is the $ operator — so use $(exc.name). (Tested on bleeding-edge devel.)

jibal (orginal) [2020-07-23T22:26:15+02:00] view original

$(exc.name)
No need for the parentheses ... $ binds less tightly than .

cdunn2001 (orginal) [2020-07-23T22:42:08+02:00] view original

Oh, I see it now. Thank you. https://nim-lang.org/docs/manual.html#types-cstring-type
A $ proc is defined for cstrings that returns a string.