AttributeError: 'FormattedValue' object has no attribute 's'

[cioma]

I have a Python source file (see attachment) that gives the following error when I try to convert it with f2format v0.4.3 on Ubuntu 18.04 64-bit using Python 3.6.5:
AttributeError: 'FormattedValue' object has no attribute 's'
register.py.zip

[JarryShaw]

Seems it's a grammar I didn't think of. Thx for reporting.

[cioma]

Many thanks!
There is another file that fails with different error, I'll open a separate issue for that.

[JarryShaw]

Expressions cannot contain ':' or '!' outside of strings or parentheses, brackets, or braces. The exception is that the '!=' operator is allowed as a special case. (c.f. PEP 498, thx to @gousaiyang)

As described in PEP 498, f-string may contains evaluated expressions as format specifiers. AttributeError in this issue and SyntaxError in issue #2 are both because of this.

• for ast.FormattedValue.format_spec, which is an ast.JoinedStr, the elements in its values attribute (a list) can either be of an ast.Str (thus has an s attribute) or other types (ast.Name in this case) [AttributeError resolved in v0.4.4.dev1 but other types not reviewed]
• when f2format extracts all entries of expressions in the f-strings, it uses brute force to find the end of expression; when the format specifiers are expressions, it has problem to find the right ending point [to revise f2format.core.convert.find_rbrace, maybe try some cleverer ways]

[cioma]

I'll also see a way to modify f-string in my code to make it easier for f2format.

[cioma]

It seems in my case f2format fails when trying to convert an f-string that has format specifiers which contain evaluated expressions (see PEP 498, Format specifiers)

E.g. a line like this:
bits = f'{bitfield.bits:{bits_width}}'

Shall be converted like this:
bits = '{:{}}'.format(bitfield.bits, bits_width)

[JarryShaw]

This issue should have been revolved in version 0.5.0. Thx for your report @cioma

[cioma]

Seems to be working fine for me, many thanks!