New submission from Mikhail <mikhail.v.gavri...@gmail.com>:
The presence of the restriction of recursion prevent making nested conditions
for the superformatter: https://github.com/ebrehault/superformatter
for example:
import string
class SuperFormatter(string.Formatter):
"""World's simplest Template engine."""
def format_field(self, value, spec):
if spec.startswith('repeat'):
template = spec.partition(':')[-1]
if type(value) is dict:
value = value.items()
return ''.join([template.format(item=item) for item in value])
elif spec == 'call':
return value()
elif spec.startswith('if'):
return (value and spec.partition(':')[-1]) or ''
else:
return super(SuperFormatter, self).format_field(value, spec)
data = {
'a1':1,
'a2':2,
'a3':3
}
tmpl = '''
{a1:if:
{a2:if:
{a2}
}
{a1}
}
'''
sf = SuperFormatter()
out = sf.format(tmpl, **data)
print(out)
Causes error:
$ python3.6 my_progs/test.py
Traceback (most recent call last):
File "my_progs/test.py", line 37, in <module>
out = sf.format(tmpl, **data)
File "/usr/lib64/python3.6/string.py", line 190, in format
return self.vformat(format_string, args, kwargs)
File "/usr/lib64/python3.6/string.py", line 194, in vformat
result, _ = self._vformat(format_string, args, kwargs, used_args, 2)
File "/usr/lib64/python3.6/string.py", line 244, in _vformat
auto_arg_index=auto_arg_index)
File "/usr/lib64/python3.6/string.py", line 244, in _vformat
auto_arg_index=auto_arg_index)
File "/usr/lib64/python3.6/string.py", line 244, in _vformat
auto_arg_index=auto_arg_index)
File "/usr/lib64/python3.6/string.py", line 201, in _vformat
raise ValueError('Max string recursion exceeded')
ValueError: Max string recursion exceeded
If there was not this restriction, then the example code is worked.
----------
components: Library (Lib)
messages: 315242
nosy: mv.gavrilov
priority: normal
severity: normal
status: open
title: Which are reasonable reason for recursion limit in function _vformat of
class Formatter lib string?
type: behavior
versions: Python 3.6
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue33272>
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