In a function definition I have the following piece of code:

    try:
        with open(requests,'rt') as f:
            tree = ElementTree.parse(f)

On execution I got:

Traceback (most recent call last):
   File "/srv/www/bin/web.py", line 362, in <module>
     build_db()
   File "/srv/www/bin/web.py", line 58, in build_db
     db_builder.build_DB()
   File "/srv/www/bin/db_builder.py", line 190, in build_DB
     tree = ElementTree.parse(f)
 TypeError: parse() missing 1 required positional argument: 'source'

There is an assignment for requests like
requests = '..' + os.path.sep + "/etc/signatures.xml"
This gives requests the value ..//etc/signatures.xml while the program runs in /srv/www/bin/

When I run the small python script like:

import xml.etree.ElementTree as ElementTree
with open('/srv/www/etc/signatures.xml','rt') as f:
    tree = ElementTree.parse(f)

all is well.
Apparently open(requests,'rt') does not raise an error.

parse() is an instance method. It should be called as tree.parse(f) (where tree is an instance of ElementTree), not ElementTree.parse(f).

Op vrijdag 11 september 2020 11:31:29 CEST schreef u:
> Serhiy Storchaka <storchaka+cpython@gmail.com> added the comment:
> 
> parse() is an instance method. It should be called as tree.parse(f) (where
> tree is an instance of ElementTree), not ElementTree.parse(f).
> 
> ----------
I have no idea how to make tree an instance.
Reading the documentation,
https://docs.python.org/2/library/xml.etree.elementtree.html,
it shows as an example:

import xml.etree.ElementTree as ET
tree = ET.parse('country_data.xml')

which is exactly what the program looks like and what my small python script 
does without an error.

-- 
fr.gr.

Freek de Kruijf

It was not clear what you do without code and full traceback.

The example uses *function* parse() from *module* ElementTree. Your code seems uses *method* parse() of *class* ElementTree.

https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.ElementTree.parse
https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.ElementTree.ElementTree.parse

Op vrijdag 11 september 2020 17:06:43 CEST schreef u:
> Serhiy Storchaka <storchaka+cpython@gmail.com> added the comment:
> 
> It was not clear what you do without code and full traceback.
> 
> The example uses *function* parse() from *module* ElementTree. Your code
> seems uses *method* parse() of *class* ElementTree.
> 
> https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.Eleme
> ntTree.parse
> https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.Elem
> entTree.ElementTree.parse

I have very little knowledge about class, instance and the other specific 
terms used in Python.

I just try to use a Python script, I found and need, and ran into this 
problem. What it does looks simple to me. As simple as the 3 line script I 
showed, which works.
Why does the larger script give this confusing error about a missing argument, 
which is present? It is a file name or file object as it should.
What I understand is that tree becomes an instance. Of what?

Is the problem caused by using ElementTree in "import xml.etree.ElementTree as 
ElementTree". Should I use "import xml.etree.ElementTree as ET" and "tree = 
ET.parse(f)"?

-- 
fr.gr.

Freek de Kruijf