Why Does a SyntaxError on One Line Sometimes Affect the Next?

SyntaxError: Invalid Syntax Persisting to Next Line

The "SyntaxError: invalid syntax" error can persist to the next line even when the problem arises line appears syntactically correct. This behavior occurs due to unbalanced parents on the previous line.

Example Code with the Error

Consider the following code snippet:

fi2=0.460*scipy.sqrt(1-(Tr-0.566)**2/(0.434**2)+0.494
guess = Pmin+(Pmax-Pmin)*((1-w**2)*fi1+(w**2)*fi2)

Although the second line seems syntactically correct, an error occurs in this line because the parentheses in the first line are not balanced:

• Open brackets: 3
• Close brackets: 2

Identifying Problems

To identify the problem, count the number of opening and closing brackets for each line:

# Tanda kurung buka: 1  2             3
#                   v  v             v
fi2=0.460*scipy.sqrt(1-(Tr-0.566)**2/(0.434**2)+0.494
#                               ^             ^
# Tanda kurung tutup:            1             2

While this method does not provide a general solution, manual understanding of the code is required to determine how the brackets should be changed.

Error Fixes in Next Python Versions

In Python 3.9 and later, the newly introduced PEG parser improves error messages and accurately identifies error locations in code source:

pax> python3 prog.py
  File "prog.py", line 1
    xyzzy = (1 +
            ^
SyntaxError: '(' was never closed

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