Validation of parameters

[Kless]

Which is the best mode for validation of parameters? I'm using the
next way but it is not well testable.

-----------------------------
if not self._foo:
try:
raise ValueError('Val ueError: foo not found')
except ValueError, err:
print (err.message)
print("Valid values: %s\n" % self.valid_foo)
sys.exit(1)

....
....
-----------------------------

[Paddy]

Re: Validation of parameters

On Aug 10, 9:13 am, Kless <jonas....@goog lemail.comwrote :

Which is the best mode for validation of parameters? I'm using the
next way but it is not well testable.
>
-----------------------------
if not self._foo:
    try:
        raise ValueError('Val ueError: foo not found')
    except ValueError, err:
        print (err.message)
        print("Valid values: %s\n" % self.valid_foo)
        sys.exit(1)
>
...
...
-----------------------------

If you just want the absense of _foo to raise an exception then why to
just reference self._foo and leave the hard work to ptyhon? Something
like:

self._foo

If it is present then fine, if it is not then an exception is raised.

Here it is in the Python shell:

>>class tmp(object):

def __init__(self):
self._foo

>>dummy = tmp()

Traceback (most recent call last):
File "<pyshell#4 >", line 1, in <module>
dummy = tmp()
File "<pyshell#3 >", line 3, in __init__
self._foo
AttributeError: 'tmp' object has no attribute '_foo'

>>>

- Paddy.

[Kless]

Re: Validation of parameters

On 10 ago, 15:03, Paddy <paddy3...@goog lemail.comwrote :

If you just want the absense of _foo to raise an exception then why to
just reference self._foo and leave the hard work to ptyhon? Something
like:
>
  self._foo
>
If it is present then fine, if it is not then an exception is raised.

It only was an example but I need show a better message. You can see
code here [1]:


[1] http://github.com/kless/cryha/tree/m...hasher.py#L141

[Terry Reedy]

Re: Validation of parameters



Kless wrote:

On 10 ago, 15:03, Paddy <paddy3...@goog lemail.comwrote :

>If you just want the absense of _foo to raise an exception then why to
>just reference self._foo and leave the hard work to ptyhon? Something
>like:
>>
> self._foo
>>
>If it is present then fine, if it is not then an exception is raised.

It only was an example but I need show a better message.

The usual idiom is
try: self._foo
except AttrError as m: #3.0
<better message>