Workbook is not closed

This is a documentation issue.

On the Working with Dates and Time page, there is an example that does not contain workbook.close() at the end. This can lead to a RuntimeError:

Exception RuntimeError: RuntimeError('sys.meta_path must be a list of import hooks',) in <bound method Workbook.__del__ of <xlsxwriter.workbook.Workbook object at 0x10617f150>> ignored

Reproduceable using XlsxWriter version 0.5.5 and Python 2.7.5. Here’s the code that reproduces the problem:

from datetime import datetime
import xlsxwriter

# Create a workbook and add a worksheet.
workbook = xlsxwriter.Workbook('datetimes.xlsx')
worksheet = workbook.add_worksheet()
bold = workbook.add_format({'bold': True})

# Expand the first columns so that the dates are visible.
worksheet.set_column('A:B', 30)

# Write the column headers.
worksheet.write('A1', 'Formatted date', bold)
worksheet.write('B1', 'Format', bold)

# Create a datetime object to use in the examples.

date_time = datetime.strptime('2013-01-23 12:30:05.123',
                              '%Y-%m-%d %H:%M:%S.%f')

# Examples date and time formats.
date_formats = (
    'dd/mm/yy',
    'mm/dd/yy',
    'dd m yy',
    'd mm yy',
    'd mmm yy',
    'd mmmm yy',
    'd mmmm yyy',
    'd mmmm yyyy',
    'dd/mm/yy hh:mm',
    'dd/mm/yy hh:mm:ss',
    'dd/mm/yy hh:mm:ss.000',
    'hh:mm',
    'hh:mm:ss',
    'hh:mm:ss.000',
)

# Start from first row after headers.
row = 1

# Write the same date and time using each of the above formats.
for date_format_str in date_formats:

    # Create a format for the date or time.
    date_format = workbook.add_format({'num_format': date_format_str,
                                      'align': 'left'})

    # Write the same date using different formats.
    worksheet.write_datetime(row, 0, date_time, date_format)

    # Also write the format string for comparison.
    worksheet.write_string(row, 1, date_format_str)

    row += 1 

[jmcnamara]

That makes sense to split it in two.

For item 1 the docs should just state that an explicit close is always required and all examples should have it included.

For reference here are the docs for close() in the Lua version of the module.

For 2 I tried very quickly to use weakref without success. A more quick and dirty way might be to catch the exception in the workbook destructor and issue a warning. Something like the following patch:

diff --git a/xlsxwriter/workbook.py b/xlsxwriter/workbook.py
index 882f0f2..62d767b 100644
--- a/xlsxwriter/workbook.py
+++ b/xlsxwriter/workbook.py
@@ -126,8 +126,12 @@ class Workbook(xmlwriter.XMLwriter):

     def __del__(self):
         """Close file in destructor if it hasn't been closed explicitly."""
-        if not self.fileclosed:
-            self.close()
+        try:
+            if not self.fileclosed:
+                self.close()
+        except:
+            raise Exception("Exception caught in workbook destructor. "
+                            "Explicit close() may be required for workbook.")

Which would give an exception like this for the example above:

$ python date_example.py
Exception Exception: Exception('Exception caught in workbook destructor. Explicit close() may be required for workbook.',) 
in <bound method Workbook.__del__ of <xlsxwriter.workbook.Workbook object at 0x103297d50>> ignored

This was just a quick fix and you may have some better suggestions.

Note, a little unfortunately the exception isn’t always RuntimeError or the try could be more explicit. On Windows and possibly some other systems/programs it raises a LookupError exception.

If you would like to tackle either of these that would be fine by me (as I said I have a bit of a backlog at the moment). If not I’ll try roll them into the next release.

[jmcnamara]

@jkyeung

That should be explicit.

Thanks John. Well spotted. That is fixed now.